Update/1.19 (#726)

Co-authored-by: FivePB <admin@fivepb.me>

api/src/main/java/com/velocitypowered/api/network/ProtocolVersion.java

@@ -57,7 +57,8 @@ public enum ProtocolVersion {
   MINECRAFT_1_17(755, "1.17"),
   MINECRAFT_1_17_1(756, "1.17.1"),
   MINECRAFT_1_18(757, "1.18", "1.18.1"),
-  MINECRAFT_1_18_2(758, "1.18.2");
+  MINECRAFT_1_18_2(758, "1.18.2"),
+  MINECRAFT_1_19(759, "1.19");
 
   private static final int SNAPSHOT_BIT = 30;
 

api/src/main/java/com/velocitypowered/api/proxy/LoginPhaseConnection.java

@@ -7,6 +7,7 @@
 
 package com.velocitypowered.api.proxy;
 
+import com.velocitypowered.api.proxy.crypto.KeyIdentifiable;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -14,7 +15,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  * Allows the server to communicate with a client logging into the proxy using login plugin
  * messages.
  */
-public interface LoginPhaseConnection extends InboundConnection {
+public interface LoginPhaseConnection extends InboundConnection, KeyIdentifiable {
   void sendLoginPluginMessage(ChannelIdentifier identifier, byte[] contents,
       MessageConsumer consumer);
 

api/src/main/java/com/velocitypowered/api/proxy/Player.java

@@ -9,6 +9,7 @@ package com.velocitypowered.api.proxy;
 
 import com.velocitypowered.api.command.CommandSource;
 import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
+import com.velocitypowered.api.proxy.crypto.KeyIdentifiable;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSource;
@@ -37,7 +38,7 @@ import org.jetbrains.annotations.NotNull;
  * Represents a player who is connected to the proxy.
  */
 public interface Player extends CommandSource, Identified, InboundConnection,
-    ChannelMessageSource, ChannelMessageSink, HoverEventSource<HoverEvent.ShowEntity>, Keyed {
+    ChannelMessageSource, ChannelMessageSink, HoverEventSource<HoverEvent.ShowEntity>, Keyed, KeyIdentifiable {
 
   /**
    * Returns the player's current username.

api/src/main/java/com/velocitypowered/api/proxy/crypto/IdentifiedKey.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.proxy.crypto;
+
+import java.security.PublicKey;
+
+/**
+ * Represents session-server cross-signed dated RSA public key.
+ */
+public interface IdentifiedKey extends KeySigned {
+
+  /**
+   * Returns RSA public key.
+   * Note: this key is at least 2048 bits but may be larger.
+   *
+   * @return the RSA public key in question
+   */
+  PublicKey getSignedPublicKey();
+
+
+  /**
+   * Validates a signature against this public key.
+   * @param signature the signature data
+   * @param toVerify the signed data
+   *
+   * @return validity of the signature
+   */
+  boolean verifyDataSignature(byte[] signature, byte[]... toVerify);
+
+}

api/src/main/java/com/velocitypowered/api/proxy/crypto/KeyIdentifiable.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.proxy.crypto;
+
+/**
+ * Identifies a type with a public RSA signature.
+ */
+public interface KeyIdentifiable {
+
+  /**
+   * Returns the timed identified key of the object context.
+   * <p>Only available in 1.19 and newer</p>
+   * @return the key or null if not available
+   */
+  IdentifiedKey getIdentifiedKey();
+}

api/src/main/java/com/velocitypowered/api/proxy/crypto/KeySigned.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.proxy.crypto;
+
+import com.google.common.annotations.Beta;
+
+import java.security.PublicKey;
+import java.time.Instant;
+
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public interface KeySigned {
+
+  /**
+   * Returns the key used to sign the object.
+   *
+   * @return the key
+   */
+  PublicKey getSigner();
+
+  /**
+   * Returns the expiry time point of the key.
+   * Note: this limit is arbitrary. RSA keys don't expire,
+   * but the signature of this key as provided by the session
+   * server will expire.
+   *
+   * @return the expiry time point
+   */
+  Instant getExpiryTemporal();
+
+
+  /**
+   * Check if the signature has expired.
+   *
+   * @return true if proxy time is after expiry time
+   */
+  default boolean hasExpired() {
+    return Instant.now().isAfter(getExpiryTemporal());
+  }
+
+  /**
+   * Retrieves the signature of the signed object.
+   *
+   * @return an RSA signature
+   */
+  @Nullable
+  byte[] getSignature();
+
+  /**
+   * Validates the signature, expiry temporal and key against the
+   * signer public key. Note: This will **not** check for
+   * expiry. You can check for expiry with {@link KeySigned#hasExpired()}.
+   * <p>DOES NOT WORK YET FOR MESSAGES AND COMMANDS!</p>
+   *
+   * @return validity of the signature
+   */
+  @Beta
+  default boolean isSignatureValid() {
+    return false;
+  }
+
+  /**
+   * Returns the signature salt or null if not salted.
+   *
+   * @return signature salt or null
+   */
+  default byte[] getSalt() {
+    return null;
+  }
+
+}

api/src/main/java/com/velocitypowered/api/proxy/crypto/SignedMessage.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.proxy.crypto;
+
+import java.util.UUID;
+
+public interface SignedMessage extends KeySigned {
+
+  /**
+   * Returns the signed message.
+   *
+   * @return the message
+   */
+  String getMessage();
+
+  /**
+   * Returns the signers UUID.
+   *
+   * @return the uuid
+   */
+  UUID getSignerUuid();
+
+  /**
+   * If true the signature of this message applies to a stylized component instead.
+   *
+   * @return signature signs preview
+   */
+  boolean isPreviewSigned();
+
+}

api/src/main/java/com/velocitypowered/api/proxy/player/TabList.java

@@ -8,6 +8,7 @@
 package com.velocitypowered.api.proxy.player;
 
 import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.util.GameProfile;
 import java.util.Collection;
 import java.util.Optional;
@@ -80,4 +81,19 @@ public interface TabList {
   @Deprecated
   TabListEntry buildEntry(GameProfile profile, @Nullable Component displayName, int latency,
       int gameMode);
+
+  /**
+   * Builds a tab list entry.
+   *
+   * @deprecated Internal usage. Use {@link TabListEntry.Builder} instead.
+   * @param profile profile
+   * @param displayName display name
+   * @param latency latency
+   * @param gameMode game mode
+   * @param key the player key
+   * @return entry
+   */
+  @Deprecated
+  TabListEntry buildEntry(GameProfile profile, @Nullable Component displayName, int latency,
+                          int gameMode, @Nullable IdentifiedKey key);
 }

api/src/main/java/com/velocitypowered/api/proxy/player/TabListEntry.java

@@ -7,6 +7,8 @@
 
 package com.velocitypowered.api.proxy.player;
 
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import com.velocitypowered.api.proxy.crypto.KeyIdentifiable;
 import com.velocitypowered.api.util.GameProfile;
 import java.util.Optional;
 import net.kyori.adventure.text.Component;
@@ -15,7 +17,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 /**
  * Represents a single entry in a {@link TabList}.
  */
-public interface TabListEntry {
+public interface TabListEntry extends KeyIdentifiable {
 
   /**
    * Returns the parent {@link TabList} of this {@code this} {@link TabListEntry}.
@@ -125,6 +127,8 @@ public interface TabListEntry {
     private int latency = 0;
     private int gameMode = 0;
 
+    private @Nullable IdentifiedKey playerKey;
+
     private Builder() {
     }
 
@@ -152,6 +156,18 @@ public interface TabListEntry {
       return this;
     }
 
+    /**
+     * Sets the {@link IdentifiedKey} of the {@link TabListEntry}.
+     *
+     * @param playerKey key to set
+     * @return {@code this}, for chaining
+     * @see TabListEntry#getIdentifiedKey()
+     */
+    public Builder playerKey(IdentifiedKey playerKey) {
+      this.playerKey = playerKey;
+      return this;
+    }
+
     /**
      * Sets the displayed name of the {@link TabListEntry}.
      *
@@ -200,7 +216,7 @@ public interface TabListEntry {
       if (profile == null) {
         throw new IllegalStateException("The GameProfile must be set when building a TabListEntry");
       }
-      return tabList.buildEntry(profile, displayName, latency, gameMode);
+      return tabList.buildEntry(profile, displayName, latency, gameMode, playerKey);
     }
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -45,6 +45,7 @@ import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.console.VelocityConsole;
+import com.velocitypowered.proxy.crypto.EncryptionUtils;
 import com.velocitypowered.proxy.event.VelocityEventManager;
 import com.velocitypowered.proxy.network.ConnectionManager;
 import com.velocitypowered.proxy.plugin.VelocityPluginManager;
@@ -55,7 +56,6 @@ import com.velocitypowered.proxy.scheduler.VelocityScheduler;
 import com.velocitypowered.proxy.server.ServerMap;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
-import com.velocitypowered.proxy.util.EncryptionUtils;
 import com.velocitypowered.proxy.util.FileSystemUtils;
 import com.velocitypowered.proxy.util.VelocityChannelRegistrar;
 import com.velocitypowered.proxy.util.bossbar.AdventureBossBarManager;
@@ -80,7 +80,6 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.ResourceBundle;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
@@ -97,7 +96,6 @@ import net.kyori.adventure.key.Key;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.translation.GlobalTranslator;
 import net.kyori.adventure.translation.TranslationRegistry;
-import net.kyori.adventure.util.UTF8ResourceBundleControl;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.asynchttpclient.AsyncHttpClient;

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -75,6 +75,7 @@ public class VelocityConfiguration implements ProxyConfig {
   @Expose private boolean enablePlayerAddressLogging = true;
   private net.kyori.adventure.text.@MonotonicNonNull Component motdAsComponent;
   private @Nullable Favicon favicon;
+  @Expose private boolean forceKeyAuthentication = true; // Added in 1.19
 
   private VelocityConfiguration(Servers servers, ForcedHosts forcedHosts, Advanced advanced,
       Query query, Metrics metrics) {
@@ -90,7 +91,7 @@ public class VelocityConfiguration implements ProxyConfig {
       PlayerInfoForwarding playerInfoForwardingMode, byte[] forwardingSecret,
       boolean onlineModeKickExistingPlayers, PingPassthroughMode pingPassthrough,
       boolean enablePlayerAddressLogging, Servers servers,ForcedHosts forcedHosts,
-      Advanced advanced, Query query, Metrics metrics) {
+      Advanced advanced, Query query, Metrics metrics, boolean forceKeyAuthentication) {
     this.bind = bind;
     this.motd = motd;
     this.showMaxPlayers = showMaxPlayers;
@@ -107,6 +108,7 @@ public class VelocityConfiguration implements ProxyConfig {
     this.advanced = advanced;
     this.query = query;
     this.metrics = metrics;
+    this.forceKeyAuthentication = forceKeyAuthentication;
   }
 
   /**
@@ -381,6 +383,10 @@ public class VelocityConfiguration implements ProxyConfig {
     return advanced.isLogPlayerConnections();
   }
 
+  public boolean isForceKeyAuthentication() {
+    return forceKeyAuthentication;
+  }
+
   @Override
   public String toString() {
     return MoreObjects.toStringHelper(this)
@@ -397,6 +403,7 @@ public class VelocityConfiguration implements ProxyConfig {
         .add("query", query)
         .add("favicon", favicon)
         .add("enablePlayerAddressLogging", enablePlayerAddressLogging)
+        .add("forceKeyAuthentication", forceKeyAuthentication)
         .toString();
   }
 
@@ -466,6 +473,7 @@ public class VelocityConfiguration implements ProxyConfig {
     String motd = config.getOrElse("motd", "&#09add3A Velocity Server");
     int maxPlayers = config.getIntOrElse("show-max-players", 500);
     Boolean onlineMode = config.getOrElse("online-mode", true);
+    Boolean forceKeyAuthentication = config.getOrElse("force-key-authentication", true);
     Boolean announceForge = config.getOrElse("announce-forge", true);
     Boolean preventClientProxyConnections = config.getOrElse("prevent-client-proxy-connections",
         true);
@@ -488,7 +496,8 @@ public class VelocityConfiguration implements ProxyConfig {
         new ForcedHosts(forcedHostsConfig),
         new Advanced(advancedConfig),
         new Query(queryConfig),
-        new Metrics(metricsConfig)
+        new Metrics(metricsConfig),
+        forceKeyAuthentication
     );
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftSessionHandler.java

@@ -20,7 +20,6 @@ package com.velocitypowered.proxy.connection;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommands;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
-import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.EncryptionRequest;
@@ -46,6 +45,13 @@ import com.velocitypowered.proxy.protocol.packet.StatusRequest;
 import com.velocitypowered.proxy.protocol.packet.StatusResponse;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteRequest;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
+import com.velocitypowered.proxy.protocol.packet.chat.LegacyChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerChatPreview;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerCommand;
+import com.velocitypowered.proxy.protocol.packet.chat.ServerChatPreview;
+import com.velocitypowered.proxy.protocol.packet.chat.ServerPlayerChat;
+import com.velocitypowered.proxy.protocol.packet.chat.SystemChat;
 import com.velocitypowered.proxy.protocol.packet.title.LegacyTitlePacket;
 import com.velocitypowered.proxy.protocol.packet.title.TitleActionbarPacket;
 import com.velocitypowered.proxy.protocol.packet.title.TitleClearPacket;
@@ -104,7 +110,7 @@ public interface MinecraftSessionHandler {
     return false;
   }
 
-  default boolean handle(Chat packet) {
+  default boolean handle(LegacyChat packet) {
     return false;
   }
 
@@ -231,4 +237,28 @@ public interface MinecraftSessionHandler {
   default boolean handle(ResourcePackResponse packet) {
     return false;
   }
+
+  default boolean handle(PlayerChat packet) {
+    return false;
+  }
+
+  default boolean handle(SystemChat packet) {
+    return false;
+  }
+
+  default boolean handle(ServerPlayerChat packet) {
+    return false;
+  }
+
+  default boolean handle(PlayerChatPreview packet) {
+    return false;
+  }
+
+  default boolean handle(ServerChatPreview packet) {
+    return false;
+  }
+
+  default boolean handle(PlayerCommand packet) {
+    return false;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/VelocityConstants.java

@@ -24,7 +24,8 @@ public class VelocityConstants {
   }
 
   public static final String VELOCITY_IP_FORWARDING_CHANNEL = "velocity:player_info";
-  public static final int FORWARDING_VERSION = 1;
+  public static final int MODERN_FORWARDING_DEFAULT = 1;
+  public static final int MODERN_FORWARDING_WITH_KEY = 2;
 
   public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/LoginSessionHandler.java

@@ -18,6 +18,8 @@
 package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.event.player.ServerLoginPluginMessageEvent;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.VelocityServer;
@@ -47,6 +49,7 @@ import javax.crypto.Mac;
 import javax.crypto.SecretKey;
 import javax.crypto.spec.SecretKeySpec;
 import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class LoginSessionHandler implements MinecraftSessionHandler {
 
@@ -78,7 +81,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         && packet.getChannel().equals(VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL)) {
       ByteBuf forwardingData = createForwardingData(configuration.getForwardingSecret(),
           serverConn.getPlayerRemoteAddressAsString(),
-          serverConn.getPlayer().getGameProfile());
+          serverConn.getPlayer().getGameProfile(), mc.getProtocolVersion(), serverConn.getPlayer().getIdentifiedKey());
       LoginPluginResponse response = new LoginPluginResponse(packet.getId(), true, forwardingData);
       mc.write(response);
       informationForwarded = true;
@@ -163,15 +166,23 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
   }
 
   private static ByteBuf createForwardingData(byte[] hmacSecret, String address,
-      GameProfile profile) {
+                                              GameProfile profile, ProtocolVersion version,
+                                              @Nullable IdentifiedKey playerKey) {
     ByteBuf forwarded = Unpooled.buffer(2048);
     try {
-      ProtocolUtils.writeVarInt(forwarded, VelocityConstants.FORWARDING_VERSION);
+      int forwardingVersion = version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0 && playerKey != null
+              ? VelocityConstants.MODERN_FORWARDING_WITH_KEY : VelocityConstants.MODERN_FORWARDING_DEFAULT;
+
+      ProtocolUtils.writeVarInt(forwarded, forwardingVersion);
       ProtocolUtils.writeString(forwarded, address);
       ProtocolUtils.writeUuid(forwarded, profile.getId());
       ProtocolUtils.writeString(forwarded, profile.getName());
       ProtocolUtils.writeProperties(forwarded, profile.getProperties());
 
+      if (forwardingVersion >= VelocityConstants.MODERN_FORWARDING_WITH_KEY) {
+        ProtocolUtils.writePlayerKey(forwarded, playerKey);
+      }
+
       SecretKey key = new SecretKeySpec(hmacSecret, "HmacSHA256");
       Mac mac = Mac.getInstance("HmacSHA256");
       mac.init(key);

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/VelocityServerConnection.java

@@ -190,7 +190,7 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
 
     mc.setProtocolVersion(protocolVersion);
     mc.setState(StateRegistry.LOGIN);
-    mc.delayedWrite(new ServerLogin(proxyPlayer.getUsername()));
+    mc.delayedWrite(new ServerLogin(proxyPlayer.getUsername(), proxyPlayer.getIdentifiedKey()));
     mc.flush();
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/client/AuthSessionHandler.java

@@ -85,7 +85,7 @@ public class AuthSessionHandler implements MinecraftSessionHandler {
 
       // Initiate a regular connection and move over to it.
       ConnectedPlayer player = new ConnectedPlayer(server, profileEvent.getGameProfile(),
-          mcConnection, inbound.getVirtualHost().orElse(null), onlineMode);
+          mcConnection, inbound.getVirtualHost().orElse(null), onlineMode, inbound.getIdentifiedKey());
       this.connectedPlayer = player;
       if (!server.canRegisterConnection(player)) {
         player.disconnect0(Component.translatable("velocity.error.already-connected-proxy",
@@ -133,6 +133,7 @@ public class AuthSessionHandler implements MinecraftSessionHandler {
     }
     ServerLoginSuccess success = new ServerLoginSuccess();
     success.setUsername(player.getUsername());
+    success.setProperties(player.getGameProfileProperties());
     success.setUuid(playerUniqueId);
     mcConnection.write(success);
 

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -42,10 +42,11 @@ import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.backend.BackendConnectionPhases;
 import com.velocitypowered.proxy.connection.backend.BungeeCordMessageResponder;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
+import com.velocitypowered.proxy.crypto.SignedChatCommand;
+import com.velocitypowered.proxy.crypto.SignedChatMessage;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
-import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.JoinGame;
 import com.velocitypowered.proxy.protocol.packet.KeepAlive;
@@ -55,6 +56,10 @@ import com.velocitypowered.proxy.protocol.packet.Respawn;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteRequest;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse.Offer;
+import com.velocitypowered.proxy.protocol.packet.chat.ChatBuilder;
+import com.velocitypowered.proxy.protocol.packet.chat.LegacyChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerCommand;
 import com.velocitypowered.proxy.protocol.packet.title.GenericTitlePacket;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import com.velocitypowered.proxy.util.CharacterUtil;
@@ -62,6 +67,8 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 import io.netty.util.ReferenceCountUtil;
+
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -90,9 +97,11 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
   private final Queue<PluginMessage> loginPluginMessages = new ConcurrentLinkedQueue<>();
   private final VelocityServer server;
   private @Nullable TabCompleteRequest outstandingTabComplete;
+  private @Nullable Instant lastChatMessage; // Added in 1.19
 
   /**
    * Constructs a client play session handler.
+   *
    * @param server the Velocity server instance
    * @param player the player
    */
@@ -101,6 +110,83 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     this.server = server;
   }
 
+  // I will not allow hacks to bypass this;
+  private boolean tickLastMessage(SignedChatMessage nextMessage) {
+    if (lastChatMessage != null && lastChatMessage.isAfter(nextMessage.getExpiryTemporal())) {
+      player.disconnect(Component.translatable("multiplayer.disconnect.out_of_order_chat"));
+      return false;
+    }
+
+    lastChatMessage = nextMessage.getExpiryTemporal();
+    return true;
+  }
+
+  private boolean validateChat(String message) {
+    if (CharacterUtil.containsIllegalCharacters(message)) {
+      player.disconnect(Component.translatable("velocity.error.illegal-chat-characters",
+          NamedTextColor.RED));
+      return false;
+    }
+    return true;
+  }
+
+  private MinecraftConnection retrieveServerConnection() {
+    VelocityServerConnection serverConnection = player.getConnectedServer();
+    if (serverConnection == null) {
+      return null;
+    }
+    return serverConnection.getConnection();
+  }
+
+  private void processCommandMessage(String message, @Nullable SignedChatCommand signedCommand,
+                                     MinecraftPacket original) {
+    server.getCommandManager().callCommandEvent(player, message)
+        .thenComposeAsync(event -> processCommandExecuteResult(message,
+            event.getResult(), signedCommand))
+        .whenComplete((ignored, throwable) -> {
+          if (server.getConfiguration().isLogCommandExecutions()) {
+            logger.info("{} -> executed command /{}", player, message);
+          }
+        })
+        .exceptionally(e -> {
+          logger.info("Exception occurred while running command for {}",
+              player.getUsername(), e);
+          player.sendMessage(Component.translatable("velocity.command.generic-error",
+              NamedTextColor.RED));
+          return null;
+        });
+  }
+
+  private void processPlayerChat(String message, @Nullable SignedChatMessage signedMessage,
+                                 MinecraftPacket original) {
+    MinecraftConnection smc = retrieveServerConnection();
+    if (smc == null) {
+      return;
+    }
+    PlayerChatEvent event = new PlayerChatEvent(player, message);
+    server.getEventManager().fire(event)
+        .thenAcceptAsync(pme -> {
+          PlayerChatEvent.ChatResult chatResult = pme.getResult();
+          if (chatResult.isAllowed()) {
+            Optional<String> eventMsg = pme.getResult().getMessage();
+            if (eventMsg.isPresent()) {
+              if (player.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0
+                  && player.getIdentifiedKey() != null) {
+                logger.warn("A plugin changed a signed chat message. The server may not accept it.");
+              }
+              smc.write(ChatBuilder.builder(player.getProtocolVersion())
+                  .message(event.getMessage()).toServer());
+            } else {
+              smc.write(original);
+            }
+          }
+        }, smc.eventLoop())
+        .exceptionally((ex) -> {
+          logger.error("Exception while handling player chat for {}", player, ex);
+          return null;
+        });
+  }
+
   @Override
   public void activated() {
     Collection<String> channels = server.getChannelRegistrar().getChannelsForProtocol(player
@@ -142,58 +228,57 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
   }
 
   @Override
-  public boolean handle(Chat packet) {
-    VelocityServerConnection serverConnection = player.getConnectedServer();
-    if (serverConnection == null) {
+  public boolean handle(PlayerCommand packet) {
+    if (!validateChat(packet.getCommand())) {
       return true;
     }
-    MinecraftConnection smc = serverConnection.getConnection();
-    if (smc == null) {
+    if (!packet.isUnsigned()) {
+      SignedChatCommand signedCommand = packet.signedContainer(player.getIdentifiedKey(), player.getUniqueId(), false);
+      if (signedCommand != null) {
+        processCommandMessage(packet.getCommand(), signedCommand, packet);
+        return true;
+      }
+    }
+
+    processCommandMessage(packet.getCommand(), null, packet);
     return true;
   }
 
+  @Override
+  public boolean handle(PlayerChat packet) {
+    if (!validateChat(packet.getMessage())) {
+      return true;
+    }
+
+    if (!packet.isUnsigned()) {
+      // Bad if spoofed
+      SignedChatMessage signedChat = packet.signedContainer(player.getIdentifiedKey(), player.getUniqueId(), false);
+      if (signedChat != null) {
+        // Server doesn't care for expiry as long as order is correct
+        if (!tickLastMessage(signedChat)) {
+          return true;
+        }
+
+        processPlayerChat(packet.getMessage(), signedChat, packet);
+        return true;
+      }
+    }
+
+    processPlayerChat(packet.getMessage(), null, packet);
+    return true;
+  }
+
+  @Override
+  public boolean handle(LegacyChat packet) {
     String msg = packet.getMessage();
-    if (CharacterUtil.containsIllegalCharacters(msg)) {
-      player.disconnect(Component.translatable("velocity.error.illegal-chat-characters",
-          NamedTextColor.RED));
+    if (!validateChat(msg)) {
       return true;
     }
 
     if (msg.startsWith("/")) {
-      String originalCommand = msg.substring(1);
-      server.getCommandManager().callCommandEvent(player, msg.substring(1))
-          .thenComposeAsync(event -> processCommandExecuteResult(originalCommand,
-              event.getResult()))
-          .whenComplete((ignored, throwable) -> {
-            if (server.getConfiguration().isLogCommandExecutions()) {
-              logger.info("{} -> executed command /{}", player, originalCommand);
-            }
-          })
-          .exceptionally(e -> {
-            logger.info("Exception occurred while running command for {}",
-                player.getUsername(), e);
-            player.sendMessage(Component.translatable("velocity.command.generic-error",
-                NamedTextColor.RED));
-            return null;
-          });
+      processCommandMessage(msg.substring(1), null, packet);
     } else {
-      PlayerChatEvent event = new PlayerChatEvent(player, msg);
-      server.getEventManager().fire(event)
-          .thenAcceptAsync(pme -> {
-            PlayerChatEvent.ChatResult chatResult = pme.getResult();
-            if (chatResult.isAllowed()) {
-              Optional<String> eventMsg = pme.getResult().getMessage();
-              if (eventMsg.isPresent()) {
-                smc.write(Chat.createServerbound(eventMsg.get()));
-              } else {
-                smc.write(packet);
-              }
-            }
-          }, smc.eventLoop())
-          .exceptionally((ex) -> {
-            logger.error("Exception while handling player chat for {}", player, ex);
-            return null;
-          });
+      processPlayerChat(msg, null, packet);
     }
     return true;
   }
@@ -368,6 +453,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
   /**
    * Handles the {@code JoinGame} packet. This function is responsible for handling the client-side
    * switching servers in Velocity.
+   *
    * @param joinGame    the join game packet
    * @param destination the new server we are connecting to
    */
@@ -452,7 +538,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         new Respawn(sentOldDim, joinGame.getPartialHashedSeed(),
             joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType(),
             false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode(),
-            joinGame.getCurrentDimensionData()));
+            joinGame.getCurrentDimensionData(), joinGame.getLastDeathPosition()));
   }
 
   private void doSafeClientServerSwitch(JoinGame joinGame) {
@@ -469,14 +555,14 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         new Respawn(tempDim, joinGame.getPartialHashedSeed(), joinGame.getDifficulty(),
             joinGame.getGamemode(), joinGame.getLevelType(),
             false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode(),
-            joinGame.getCurrentDimensionData()));
+            joinGame.getCurrentDimensionData(), joinGame.getLastDeathPosition()));
 
     // Now send a respawn packet in the correct dimension.
     player.getConnection().delayedWrite(
         new Respawn(joinGame.getDimension(), joinGame.getPartialHashedSeed(),
             joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType(),
             false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode(),
-            joinGame.getCurrentDimensionData()));
+            joinGame.getCurrentDimensionData(), joinGame.getLastDeathPosition()));
   }
 
   public List<UUID> getServerBossBars() {
@@ -619,8 +705,10 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         });
   }
 
+
   private CompletableFuture<Void> processCommandExecuteResult(String originalCommand,
-      CommandResult result) {
+                                                              CommandResult result,
+                                                              @Nullable SignedChatCommand signedCommand) {
     if (result == CommandResult.denied()) {
       return CompletableFuture.completedFuture(null);
     }
@@ -628,13 +716,30 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     MinecraftConnection smc = player.ensureAndGetCurrentServer().ensureConnected();
     String commandToRun = result.getCommand().orElse(originalCommand);
     if (result.isForwardToServer()) {
-      return CompletableFuture.runAsync(() -> smc.write(Chat.createServerbound("/"
-          + commandToRun)), smc.eventLoop());
+      ChatBuilder write = ChatBuilder
+          .builder(player.getProtocolVersion())
+          .asPlayer(player);
+
+      if (signedCommand != null && commandToRun.equals(signedCommand.getBaseCommand())) {
+        write.message(signedCommand);
+      } else {
+        write.message("/" + commandToRun);
+      }
+      return CompletableFuture.runAsync(() -> smc.write(write.toServer()), smc.eventLoop());
     } else {
       return server.getCommandManager().executeImmediatelyAsync(player, commandToRun)
           .thenAcceptAsync(hasRun -> {
             if (!hasRun) {
-              smc.write(Chat.createServerbound("/" + commandToRun));
+              ChatBuilder write = ChatBuilder
+                  .builder(player.getProtocolVersion())
+                  .asPlayer(player);
+
+              if (signedCommand != null && commandToRun.equals(signedCommand.getBaseCommand())) {
+                write.message(signedCommand);
+              } else {
+                write.message("/" + commandToRun);
+              }
+              smc.write(write.toServer());
             }
           }, smc.eventLoop());
     }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -41,6 +41,8 @@ import com.velocitypowered.api.permission.Tristate;
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ServerConnection;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import com.velocitypowered.api.proxy.crypto.KeyIdentifiable;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.player.PlayerSettings;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
@@ -56,13 +58,14 @@ import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
-import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.HeaderAndFooter;
 import com.velocitypowered.proxy.protocol.packet.KeepAlive;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import com.velocitypowered.proxy.protocol.packet.ResourcePackRequest;
+import com.velocitypowered.proxy.protocol.packet.chat.ChatBuilder;
+import com.velocitypowered.proxy.protocol.packet.chat.LegacyChat;
 import com.velocitypowered.proxy.protocol.packet.title.GenericTitlePacket;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import com.velocitypowered.proxy.tablist.VelocityTabList;
@@ -109,7 +112,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.jetbrains.annotations.NotNull;
 
-public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
+public class ConnectedPlayer implements MinecraftConnectionAssociation, Player, KeyIdentifiable {
 
   private static final int MAX_PLUGIN_CHANNELS = 1024;
   private static final PlainTextComponentSerializer PASS_THRU_TRANSLATE = PlainTextComponentSerializer.builder()
@@ -159,9 +162,10 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
           .build();
   private @Nullable String clientBrand;
   private @Nullable Locale effectiveLocale;
+  private @Nullable IdentifiedKey playerKey;
 
   ConnectedPlayer(VelocityServer server, GameProfile profile, MinecraftConnection connection,
-      @Nullable InetSocketAddress virtualHost, boolean onlineMode) {
+      @Nullable InetSocketAddress virtualHost, boolean onlineMode, @Nullable IdentifiedKey playerKey) {
     this.server = server;
     this.profile = profile;
     this.connection = connection;
@@ -176,6 +180,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     } else {
       this.tabList = new VelocityTabListLegacy(this);
     }
+    this.playerKey = playerKey;
   }
 
   @Override
@@ -311,7 +316,9 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   @Override
   public void sendMessage(@NonNull Identity identity, @NonNull Component message) {
     Component translated = translateMessage(message);
-    connection.write(Chat.createClientbound(identity, translated, this.getProtocolVersion()));
+
+    connection.write(ChatBuilder.builder(this.getProtocolVersion())
+            .component(translated).forIdentity(identity).toClient());
   }
 
   @Override
@@ -321,9 +328,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     Preconditions.checkNotNull(type, "type");
 
     Component translated = translateMessage(message);
-    Chat packet = Chat.createClientbound(identity, translated, this.getProtocolVersion());
-    packet.setType(type == MessageType.CHAT ? Chat.CHAT_TYPE : Chat.SYSTEM_TYPE);
-    connection.write(packet);
+
+    connection.write(ChatBuilder.builder(this.getProtocolVersion())
+            .component(translated).forIdentity(identity)
+            .setType(type == MessageType.CHAT ? ChatBuilder.ChatType.CHAT : ChatBuilder.ChatType.SYSTEM)
+            .toClient());
   }
 
   @Override
@@ -344,10 +353,10 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
       JsonObject object = new JsonObject();
       object.addProperty("text", LegacyComponentSerializer.legacySection()
           .serialize(translated));
-      Chat chat = new Chat();
-      chat.setMessage(object.toString());
-      chat.setType(Chat.GAME_INFO_TYPE);
-      connection.write(chat);
+      LegacyChat legacyChat = new LegacyChat();
+      legacyChat.setMessage(object.toString());
+      legacyChat.setType(LegacyChat.GAME_INFO_TYPE);
+      connection.write(legacyChat);
     }
   }
 
@@ -883,10 +892,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
 
   @Override
   public void spoofChatInput(String input) {
-    Preconditions.checkArgument(input.length() <= Chat.MAX_SERVERBOUND_MESSAGE_LENGTH,
-        "input cannot be greater than " + Chat.MAX_SERVERBOUND_MESSAGE_LENGTH
+    Preconditions.checkArgument(input.length() <= LegacyChat.MAX_SERVERBOUND_MESSAGE_LENGTH,
+        "input cannot be greater than " + LegacyChat.MAX_SERVERBOUND_MESSAGE_LENGTH
             + " characters in length");
-    ensureBackendConnection().write(Chat.createServerbound(input));
+    ensureBackendConnection().write(ChatBuilder.builder(getProtocolVersion())
+            .asPlayer(this).message(input).toServer());
   }
 
   @Override
@@ -1055,6 +1065,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     return knownChannels;
   }
 
+  @Override
+  public IdentifiedKey getIdentifiedKey() {
+    return playerKey;
+  }
+
   private class IdentityImpl implements Identity {
     @Override
     public @NonNull UUID uuid() {

proxy/src/main/java/com/velocitypowered/proxy/connection/client/InitialLoginSessionHandler.java

@@ -20,12 +20,15 @@ package com.velocitypowered.proxy.connection.client;
 import static com.google.common.net.UrlEscapers.urlFormParameterEscaper;
 import static com.velocitypowered.proxy.VelocityServer.GENERAL_GSON;
 import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
-import static com.velocitypowered.proxy.util.EncryptionUtils.decryptRsa;
-import static com.velocitypowered.proxy.util.EncryptionUtils.generateServerId;
+import static com.velocitypowered.proxy.crypto.EncryptionUtils.decryptRsa;
+import static com.velocitypowered.proxy.crypto.EncryptionUtils.generateServerId;
 
 import com.google.common.base.Preconditions;
+import com.google.common.primitives.Longs;
 import com.velocitypowered.api.event.connection.PreLoginEvent;
 import com.velocitypowered.api.event.connection.PreLoginEvent.PreLoginComponentResult;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
@@ -77,6 +80,23 @@ public class InitialLoginSessionHandler implements MinecraftSessionHandler {
   public boolean handle(ServerLogin packet) {
     assertState(LoginState.LOGIN_PACKET_EXPECTED);
     this.currentState = LoginState.LOGIN_PACKET_RECEIVED;
+    IdentifiedKey playerKey = packet.getPlayerKey();
+    if (playerKey != null) {
+      if (playerKey.hasExpired()) {
+        inbound.disconnect(Component.translatable("multiplayer.disconnect.invalid_public_key_signature"));
+        return true;
+      }
+
+      if (!playerKey.isSignatureValid()) {
+        inbound.disconnect(Component.translatable("multiplayer.disconnect.invalid_public_key"));
+        return true;
+      }
+    } else if (mcConnection.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0
+            && server.getConfiguration().isForceKeyAuthentication()) {
+      inbound.disconnect(Component.translatable("multiplayer.disconnect.missing_public_key"));
+      return true;
+    }
+    inbound.setPlayerKey(playerKey);
     this.login = packet;
 
     PreLoginEvent event = new PreLoginEvent(inbound, login.getUsername());
@@ -135,7 +155,6 @@ public class InitialLoginSessionHandler implements MinecraftSessionHandler {
   public boolean handle(EncryptionResponse packet) {
     assertState(LoginState.ENCRYPTION_REQUEST_SENT);
     this.currentState = LoginState.ENCRYPTION_RESPONSE_RECEIVED;
-
     ServerLogin login = this.login;
     if (login == null) {
       throw new IllegalStateException("No ServerLogin packet received yet.");
@@ -147,10 +166,17 @@ public class InitialLoginSessionHandler implements MinecraftSessionHandler {
 
     try {
       KeyPair serverKeyPair = server.getServerKeyPair();
+      if (inbound.getIdentifiedKey() != null) {
+        IdentifiedKey playerKey = inbound.getIdentifiedKey();
+        if (!playerKey.verifyDataSignature(packet.getVerifyToken(), verify, Longs.toByteArray(packet.getSalt()))) {
+          throw new IllegalStateException("Invalid client public signature.");
+        }
+      } else {
         byte[] decryptedVerifyToken = decryptRsa(serverKeyPair, packet.getVerifyToken());
         if (!MessageDigest.isEqual(verify, decryptedVerifyToken)) {
           throw new IllegalStateException("Unable to successfully decrypt the verification token.");
         }
+      }
 
       byte[] decryptedSharedSecret = decryptRsa(serverKeyPair, packet.getSharedSecret());
       String serverId = generateServerId(decryptedSharedSecret, serverKeyPair.getPublic());

proxy/src/main/java/com/velocitypowered/proxy/connection/client/LoginInboundConnection.java

@@ -19,6 +19,8 @@ package com.velocitypowered.proxy.connection.client;
 
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.LoginPhaseConnection;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import com.velocitypowered.api.proxy.crypto.KeyIdentifiable;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.protocol.packet.LoginPluginMessage;
@@ -32,9 +34,10 @@ import java.util.Optional;
 import java.util.Queue;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import space.vectrix.flare.fastutil.Int2ObjectSyncMap;
 
-public class LoginInboundConnection implements LoginPhaseConnection {
+public class LoginInboundConnection implements LoginPhaseConnection, KeyIdentifiable {
 
   private static final AtomicIntegerFieldUpdater<LoginInboundConnection> SEQUENCE_UPDATER =
       AtomicIntegerFieldUpdater.newUpdater(LoginInboundConnection.class, "sequenceCounter");
@@ -45,6 +48,7 @@ public class LoginInboundConnection implements LoginPhaseConnection {
   private final Queue<LoginPluginMessage> loginMessagesToSend;
   private volatile Runnable onAllMessagesHandled;
   private volatile boolean loginEventFired;
+  private @MonotonicNonNull IdentifiedKey playerKey;
 
   LoginInboundConnection(
       InitialInboundConnection delegate) {
@@ -149,4 +153,13 @@ public class LoginInboundConnection implements LoginPhaseConnection {
   MinecraftConnection delegatedConnection() {
     return delegate.getConnection();
   }
+
+  public void setPlayerKey(IdentifiedKey playerKey) {
+    this.playerKey = playerKey;
+  }
+
+  @Override
+  public IdentifiedKey getIdentifiedKey() {
+    return playerKey;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/ChatData.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.connection.registry;
+
+/*
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import net.kyori.adventure.nbt.*;
+import net.kyori.adventure.text.format.NamedTextColor;
+import net.kyori.adventure.text.format.TextDecoration;
+import net.kyori.adventure.text.format.TextFormat;
+import net.kyori.adventure.translation.Translatable;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+*/
+
+// TODO Implement
+public class ChatData {
+    /*
+    private static final ListBinaryTag EMPTY_LIST_TAG = ListBinaryTag.empty();
+
+
+    private final String identifier;
+    private final int id;
+    private final Map<>
+
+
+    public static class Decoration implements Translatable {
+
+        private final List<String> parameters;
+        private final List<TextFormat> style;
+        private final String translationKey;
+
+        public List<String> getParameters() {
+            return parameters;
+        }
+
+        public List<TextFormat> getStyle() {
+            return style;
+        }
+
+        @Override
+        public @NotNull String translationKey() {
+            return translationKey;
+        }
+
+        public Decoration(List<String> parameters, List<TextFormat> style, String translationKey) {
+            this.parameters = Preconditions.checkNotNull(parameters);
+            this.style = Preconditions.checkNotNull(style);
+            this.translationKey = Preconditions.checkNotNull(translationKey);
+            Preconditions.checkArgument(translationKey.length() > 0);
+        }
+
+        public static Decoration decodeRegistryEntry(CompoundBinaryTag toDecode) {
+            ImmutableList.Builder<String> parameters = ImmutableList.builder();
+            ListBinaryTag paramList = toDecode.getList("parameters", EMPTY_LIST_TAG);
+            if (paramList != EMPTY_LIST_TAG) {
+                paramList.forEach(binaryTag -> parameters.add(binaryTag.toString()));
+            }
+
+            ImmutableList.Builder<TextFormat> style = ImmutableList.builder();
+            CompoundBinaryTag styleList = toDecode.getCompound("style");
+            for (String key : styleList.keySet()) {
+                if ("color".equals(key)) {
+                    NamedTextColor color = Preconditions.checkNotNull(
+                            NamedTextColor.NAMES.value(styleList.getString(key)));
+                    style.add(color);
+                } else {
+                    // Key is a Style option instead
+                    TextDecoration deco = TextDecoration.NAMES.value(key);
+                    // This wouldn't be here if it wasn't applied, but here it goes anyway:
+                    byte val = styleList.getByte(key);
+                    if (val != 0) {
+                        style.add(deco);
+                    }
+                }
+            }
+
+            String translationKey = toDecode.getString("translation_key");
+
+            return new Decoration(parameters.build(), style.build(), translationKey);
+        }
+
+        public void encodeRegistryEntry(CompoundBinaryTag )
+
+    }
+
+    public static enum Priority {
+        SYSTEM,
+        CHAT
+    }
+*/
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionData.java

@@ -45,9 +45,12 @@ public final class DimensionData {
   private final @Nullable String effects;
   private final @Nullable Integer minY; // Required and added by 1.17
   private final @Nullable Integer height; // Required and added by 1.17
+  private final @Nullable Integer monsterSpawnBlockLightLimit; // Required and added by 1.19
+  private final @Nullable Integer monsterSpawnLightLevel; // Required and added by 1.19
 
   /**
    * Initializes a new {@link DimensionData} instance.
+   *
    * @param registryIdentifier          the identifier for the dimension from the registry.
    * @param dimensionId                 the dimension ID contained in the registry (the "id" tag)
    * @param isNatural                   indicates if the dimension use natural world generation (e.g. overworld)
@@ -68,6 +71,9 @@ public final class DimensionData {
    * @param effects                     optional, unknown purpose
    * @param minY                        the world effective lowest build-level
    * @param height                      the world height above zero
+   * @param monsterSpawnBlockLightLimit an integer controlling the block light needed to prevent monster spawns.
+   * @param monsterSpawnLightLevel      an int provider which is evaluated to find a value to compare the current
+   *                                    overall brightness with to determine if a monster should be allowed to spawn.
    */
   public DimensionData(String registryIdentifier,
                        @Nullable Integer dimensionId,
@@ -80,7 +86,10 @@ public final class DimensionData {
                        @Nullable Long fixedTime, @Nullable Boolean createDragonFight,
                        @Nullable Double coordinateScale,
                        @Nullable String effects,
-      @Nullable Integer minY, @Nullable Integer height) {
+                       @Nullable Integer minY, @Nullable Integer height, @Nullable Integer monsterSpawnBlockLightLimit,
+                       @Nullable Integer monsterSpawnLightLevel) {
+    this.monsterSpawnBlockLightLimit = monsterSpawnBlockLightLimit;
+    this.monsterSpawnLightLevel = monsterSpawnLightLevel;
     Preconditions.checkNotNull(
         registryIdentifier, "registryIdentifier cannot be null");
     Preconditions.checkArgument(registryIdentifier.length() > 0,
@@ -201,7 +210,7 @@ public final class DimensionData {
     return new DimensionData(registryIdentifier, dimensionId, isNatural, ambientLight, isShrunk,
         isUltrawarm, hasCeiling, hasSkylight, isPiglinSafe, doBedsWork, doRespawnAnchorsWork,
         hasRaids, logicalHeight, burningBehaviourIdentifier, fixedTime, createDragonFight,
-        coordinateScale, effects, minY, height);
+        coordinateScale, effects, minY, height, monsterSpawnBlockLightLimit, monsterSpawnLightLevel);
   }
 
   public boolean isUnannotated() {
@@ -240,22 +249,34 @@ public final class DimensionData {
         : null;
     Integer minY = details.keySet().contains("min_y") ? details.getInt("min_y") : null;
     Integer height = details.keySet().contains("height") ? details.getInt("height") : null;
+    Integer monsterSpawnBlockLightLimit = details.keySet().contains("monster_spawn_block_light_limit")
+        ? details.getInt("monster_spawn_block_light_limit") : null;
+    Integer monsterSpawnLightLevel =
+        details.keySet().contains("monster_spawn_light_level") ? details.getInt("monster_spawn_block_light_limit") :
+            null;
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_17) >= 0) {
       Preconditions.checkNotNull(height,
           "DimensionData requires 'height' to be present for this version");
       Preconditions.checkNotNull(minY,
           "DimensionData requires 'minY' to be present for this version");
     }
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      Preconditions.checkNotNull(monsterSpawnBlockLightLimit,
+          "DimensionData requires 'monster_spawn_block_light_limit' to be present for this version.");
+      Preconditions.checkNotNull(monsterSpawnLightLevel,
+          "DimensionData requires 'monster_spawn_light_level' to be present for this version.");
+    }
     return new DimensionData(
         UNKNOWN_DIMENSION_ID, null, isNatural, ambientLight, isShrunk,
         isUltrawarm, hasCeiling, hasSkylight, isPiglinSafe, doBedsWork, doRespawnAnchorsWork,
         hasRaids, logicalHeight, burningBehaviourIdentifier, fixedTime, hasEnderdragonFight,
-        coordinateScale, effects, minY, height);
+        coordinateScale, effects, minY, height, monsterSpawnBlockLightLimit, monsterSpawnLightLevel);
   }
 
   /**
    * Parses a given CompoundTag to a DimensionData instance. Assumes the data is part of a
    * dimension registry.
+   *
    * @param dimTag  the compound from the registry to read
    * @param version the protocol version
    * @return game dimension data
@@ -278,6 +299,7 @@ public final class DimensionData {
 
   /**
    * Encodes the Dimension data as CompoundTag.
+   *
    * @param version the version to serialize as
    * @return compound containing the dimension data
    */
@@ -301,6 +323,7 @@ public final class DimensionData {
 
   /**
    * Serializes details of this dimension.
+   *
    * @return serialized details of this dimension
    */
   public CompoundBinaryTag serializeDimensionDetails() {
@@ -335,6 +358,12 @@ public final class DimensionData {
     if (height != null) {
       ret.putInt("height", height);
     }
+    if (monsterSpawnBlockLightLimit != null) {
+      ret.putInt("monster_spawn_block_light_limit", monsterSpawnBlockLightLimit);
+    }
+    if (monsterSpawnLightLevel != null) {
+      ret.putInt("monster_spawn_light_level", monsterSpawnLightLevel);
+    }
     return ret.build();
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/crypto/EncryptionUtils.java

@@ -0,0 +1,263 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.crypto;
+
+import com.google.common.base.Preconditions;
+import com.google.common.io.ByteStreams;
+import com.velocitypowered.proxy.util.except.QuietDecoderException;
+import it.unimi.dsi.fastutil.Pair;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.charset.StandardCharsets;
+import java.security.GeneralSecurityException;
+import java.security.Key;
+import java.security.KeyFactory;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.Signature;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.Base64;
+import javax.crypto.Cipher;
+
+public enum EncryptionUtils {
+  ;
+
+  public static final Pair<String, String> PEM_RSA_PUBLIC_KEY_DESCRIPTOR =
+          Pair.of("-----BEGIN RSA PUBLIC KEY-----", "-----END RSA PUBLIC KEY-----");
+  public static final Pair<String, String> PEM_RSA_PRIVATE_KEY_DESCRIPTOR =
+          Pair.of("-----BEGIN RSA PRIVATE KEY-----", "-----END RSA PRIVATE KEY-----");
+
+  public static final String SHA1_WITH_RSA = "SHA1withRSA";
+  public static final String SHA256_WITH_RSA = "SHA256withRSA";
+
+  public static final QuietDecoderException INVALID_SIGNATURE
+          = new QuietDecoderException("Incorrectly signed chat message");
+  public static final QuietDecoderException PREVIEW_SIGNATURE_MISSING
+          = new QuietDecoderException("Unsigned chat message requested signed preview");
+  public static final byte[] EMPTY = new byte[0];
+  private static PublicKey YGGDRASIL_SESSION_KEY;
+  private static KeyFactory RSA_KEY_FACTORY;
+
+  private static final Base64.Encoder MIME_SPECIAL_ENCODER
+          = Base64.getMimeEncoder(76, "\n".getBytes(StandardCharsets.UTF_8));
+
+  static {
+    try {
+      RSA_KEY_FACTORY = KeyFactory.getInstance("RSA");
+    } catch (NoSuchAlgorithmException e) {
+      throw new RuntimeException(e);
+    }
+
+    try {
+      byte[] bytes = ByteStreams.toByteArray(
+              EncryptionUtils.class.getClassLoader().getResourceAsStream("yggdrasil_session_pubkey.der"));
+      YGGDRASIL_SESSION_KEY =  parseRsaPublicKey(bytes);
+    } catch (IOException | NullPointerException err) {
+      throw new RuntimeException(err);
+    }
+  }
+
+  public static PublicKey getYggdrasilSessionKey() {
+    return YGGDRASIL_SESSION_KEY;
+  }
+
+  /**
+   * Verifies a key signature.
+   *
+   * @param algorithm the signature algorithm
+   * @param base the public key to verify with
+   * @param signature the signature to verify against
+   * @param toVerify the byte array(s) of data to verify
+   * @return validity of the signature
+   */
+  public static boolean verifySignature(String algorithm, PublicKey base, byte[] signature, byte[]... toVerify) {
+    Preconditions.checkArgument(toVerify.length > 0);
+    try {
+      Signature construct = Signature.getInstance(algorithm);
+      construct.initVerify(base);
+      for (byte[] bytes : toVerify) {
+        construct.update(bytes);
+      }
+      return construct.verify(signature);
+    } catch (GeneralSecurityException e) {
+      throw new IllegalArgumentException("Invalid signature parameters");
+    }
+  }
+
+  /**
+   * Generates a signature for input data.
+   *
+   * @param algorithm the signature algorithm
+   * @param base the private key to sign with
+   * @param toSign the byte array(s) of data to sign
+   * @return the generated signature
+   */
+  public static byte[] generateSignature(String algorithm, PrivateKey base, byte[]... toSign) {
+    Preconditions.checkArgument(toSign.length > 0);
+    try {
+      Signature construct = Signature.getInstance(algorithm);
+      construct.initSign(base);
+      for (byte[] bytes : toSign) {
+        construct.update(bytes);
+      }
+      return construct.sign();
+    } catch (GeneralSecurityException e) {
+      throw new IllegalArgumentException("Invalid signature parameters");
+    }
+  }
+
+  /**
+   * Encodes a long array as Big-endian byte array.
+   *
+   * @param bits the long (array) of numbers to encode
+   * @return the encoded bytes
+   */
+  public static byte[] longToBigEndianByteArray(long... bits) {
+    ByteBuffer ret = ByteBuffer.allocate(8 * bits.length).order(ByteOrder.BIG_ENDIAN);
+    for (long put : bits) {
+      ret.putLong(put);
+    }
+    return ret.array();
+  }
+
+  public static String encodeUrlEncoded(byte[] data) {
+    return MIME_SPECIAL_ENCODER.encodeToString(data);
+  }
+
+  public static byte[] decodeUrlEncoded(String toParse) {
+    return Base64.getMimeDecoder().decode(toParse);
+  }
+
+  /**
+   * Parse a cer-encoded RSA key into its key bytes.
+   *
+   * @param toParse the cer-encoded key String
+   * @param descriptors the type of key
+   * @return the parsed key bytes
+   */
+  public static byte[] parsePemEncoded(String toParse, Pair<String, String> descriptors) {
+    int startIdx = toParse.indexOf(descriptors.first());
+    Preconditions.checkArgument(startIdx >= 0);
+    int firstLen = descriptors.first().length();
+    int endIdx = toParse.indexOf(descriptors.second(), firstLen + startIdx) + 1;
+    Preconditions.checkArgument(endIdx > 0);
+    return decodeUrlEncoded(toParse.substring(startIdx + firstLen, endIdx));
+  }
+
+  /**
+   * Encodes an RSA key as String cer format.
+   *
+   * @param toEncode the private or public RSA key
+   * @return the encoded key cer
+   */
+  public static String pemEncodeRsaKey(Key toEncode) {
+    Preconditions.checkNotNull(toEncode);
+    Pair<String, String> encoder;
+    if (toEncode instanceof PublicKey) {
+      encoder = PEM_RSA_PUBLIC_KEY_DESCRIPTOR;
+    } else if (toEncode instanceof PrivateKey) {
+      encoder = PEM_RSA_PRIVATE_KEY_DESCRIPTOR;
+    } else {
+      throw new IllegalArgumentException("Invalid key type");
+    }
+
+    return encoder.first() + "\n"
+            + encodeUrlEncoded(toEncode.getEncoded()) + "\n"
+            + encoder.second() + "\n";
+  }
+
+  /**
+   * Parse an RSA public key from key bytes.
+   *
+   * @param keyValue the key bytes
+   * @return the generated key
+   */
+  public static PublicKey parseRsaPublicKey(byte[] keyValue) {
+    try {
+      return RSA_KEY_FACTORY.generatePublic(new X509EncodedKeySpec(keyValue));
+    } catch (InvalidKeySpecException e) {
+      throw new IllegalArgumentException("Invalid key bytes");
+    }
+  }
+
+  /**
+   * Generates an RSA key pair.
+   *
+   * @param keysize the key size (in bits) for the RSA key pair
+   * @return the generated key pair
+   */
+  public static KeyPair createRsaKeyPair(final int keysize) {
+    try {
+      final KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
+      generator.initialize(keysize);
+      return generator.generateKeyPair();
+    } catch (final NoSuchAlgorithmException e) {
+      throw new RuntimeException("Unable to generate RSA keypair", e);
+    }
+  }
+
+  /**
+   * Generates a hex digest in two's complement form for use with the Mojang joinedServer endpoint.
+   *
+   * @param digest the bytes to digest
+   * @return the hex digest
+   */
+  public static String twosComplementHexdigest(byte[] digest) {
+    return new BigInteger(digest).toString(16);
+  }
+
+  /**
+   * Decrypts an RSA message.
+   *
+   * @param keyPair the key pair to use
+   * @param bytes the bytes of the encrypted message
+   * @return the decrypted message
+   * @throws GeneralSecurityException if the message couldn't be decoded
+   */
+  public static byte[] decryptRsa(KeyPair keyPair, byte[] bytes) throws GeneralSecurityException {
+    Cipher cipher = Cipher.getInstance("RSA");
+    cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate());
+    return cipher.doFinal(bytes);
+  }
+
+  /**
+   * Generates the server ID for the hasJoined endpoint.
+   *
+   * @param sharedSecret the shared secret between the client and the proxy
+   * @param key the RSA public key
+   * @return the server ID
+   */
+  public static String generateServerId(byte[] sharedSecret, PublicKey key) {
+    try {
+      MessageDigest digest = MessageDigest.getInstance("SHA-1");
+      digest.update(sharedSecret);
+      digest.update(key.getEncoded());
+      return twosComplementHexdigest(digest.digest());
+    } catch (NoSuchAlgorithmException e) {
+      throw new AssertionError(e);
+    }
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/crypto/IdentifiedKeyImpl.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.crypto;
+
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import java.nio.charset.StandardCharsets;
+import java.security.PublicKey;
+import java.time.Instant;
+import java.util.Arrays;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+public class IdentifiedKeyImpl implements IdentifiedKey {
+
+  private final PublicKey publicKey;
+  private final byte[] signature;
+  private final Instant expiryTemporal;
+  private @MonotonicNonNull Boolean isSignatureValid;
+
+  public IdentifiedKeyImpl(byte[] keyBits, long expiry,
+                            byte[] signature) {
+    this(EncryptionUtils.parseRsaPublicKey(keyBits), Instant.ofEpochMilli(expiry), signature);
+  }
+
+  /**
+   * Creates an Identified key from data.
+   */
+  public IdentifiedKeyImpl(PublicKey publicKey, Instant expiryTemporal, byte[] signature) {
+    this.publicKey = publicKey;
+    this.expiryTemporal = expiryTemporal;
+    this.signature = signature;
+  }
+
+  @Override
+  public PublicKey getSignedPublicKey() {
+    return publicKey;
+  }
+
+  @Override
+  public PublicKey getSigner() {
+    return EncryptionUtils.getYggdrasilSessionKey();
+  }
+
+  @Override
+  public Instant getExpiryTemporal() {
+    return expiryTemporal;
+  }
+
+  @Override
+  public byte[] getSignature() {
+    return signature;
+  }
+
+  @Override
+  public boolean isSignatureValid() {
+    if (isSignatureValid == null) {
+      String pemKey = EncryptionUtils.pemEncodeRsaKey(publicKey);
+      long expires = expiryTemporal.toEpochMilli();
+      byte[] toVerify = ("" + expires + pemKey).getBytes(StandardCharsets.US_ASCII);
+      isSignatureValid = EncryptionUtils.verifySignature(
+              EncryptionUtils.SHA1_WITH_RSA, EncryptionUtils.getYggdrasilSessionKey(), signature, toVerify);
+    }
+    return isSignatureValid;
+  }
+
+  @Override
+  public boolean verifyDataSignature(byte[] signature, byte[]... toVerify) {
+    try {
+      return EncryptionUtils.verifySignature(EncryptionUtils.SHA256_WITH_RSA, publicKey, signature, toVerify);
+    } catch (IllegalArgumentException e) {
+      return false;
+    }
+  }
+
+  @Override
+  public String toString() {
+    return "IdentifiedKeyImpl{"
+        + "publicKey=" + publicKey
+        + ", signature=" + Arrays.toString(signature)
+        + ", expiryTemporal=" + expiryTemporal
+        + ", isSignatureValid=" + isSignatureValid
+        + '}';
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/crypto/SignedChatCommand.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.crypto;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.crypto.KeySigned;
+import java.security.PublicKey;
+import java.time.Instant;
+import java.util.Map;
+import java.util.UUID;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class SignedChatCommand implements KeySigned {
+  private final String command;
+  private final PublicKey signer;
+  private final Instant expiry;
+  private final byte[] salt;
+  private final UUID sender;
+  //private final boolean isValid;
+  private final boolean isPreviewSigned;
+
+  private final Map<String, byte[]> signatures;
+
+  /**
+   * Create a signed command from data.
+   */
+  public SignedChatCommand(String command, PublicKey signer, UUID sender,
+                           Instant expiry, Map<String, byte[]> signature, byte[] salt, boolean isPreviewSigned) {
+    this.command = Preconditions.checkNotNull(command);
+    this.signer = Preconditions.checkNotNull(signer);
+    this.sender = Preconditions.checkNotNull(sender);
+    this.signatures = Preconditions.checkNotNull(signature);
+    this.expiry = Preconditions.checkNotNull(expiry);
+    this.salt = Preconditions.checkNotNull(salt);
+    this.isPreviewSigned = isPreviewSigned;
+
+  }
+
+  @Override
+  public PublicKey getSigner() {
+    return signer;
+  }
+
+  @Override
+  public Instant getExpiryTemporal() {
+    return expiry;
+  }
+
+  @Override
+  public @Nullable byte[] getSignature() {
+    return null;
+  }
+
+  @Override
+  public byte[] getSalt() {
+    return salt;
+  }
+
+  public String getBaseCommand() {
+    return command;
+  }
+
+
+  public Map<String, byte[]> getSignatures() {
+    return signatures;
+  }
+
+  public boolean isPreviewSigned() {
+    return isPreviewSigned;
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/crypto/SignedChatMessage.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.crypto;
+
+import com.google.common.base.Preconditions;
+import com.google.common.primitives.Longs;
+import com.velocitypowered.api.proxy.crypto.SignedMessage;
+import com.velocitypowered.proxy.util.except.QuietDecoderException;
+import java.nio.charset.StandardCharsets;
+import java.security.KeyPair;
+import java.security.PublicKey;
+import java.time.Duration;
+import java.time.Instant;
+import java.time.temporal.TemporalAmount;
+import java.util.UUID;
+
+import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class SignedChatMessage implements SignedMessage {
+
+  private static final QuietDecoderException INVALID_SIGNED_CHAT =
+      new QuietDecoderException("Couldn't parse chat message");
+
+  public static final TemporalAmount EXPIRY_TIME = Duration.ofMinutes(2L);
+
+  private final String message;
+  private final PublicKey signer;
+  private final byte[] signature;
+  private final Instant expiry;
+  private final byte[] salt;
+  private final UUID sender;
+  //private final boolean isValid;
+  private final boolean isPreviewSigned;
+
+  /**
+   * Create a signed message from data.
+   */
+  public SignedChatMessage(String message, PublicKey signer, UUID sender,
+                           Instant expiry, byte[] signature, byte[] salt, boolean isPreviewSigned) {
+    this.message = Preconditions.checkNotNull(message);
+    this.signer = Preconditions.checkNotNull(signer);
+    this.sender = Preconditions.checkNotNull(sender);
+    this.signature = Preconditions.checkNotNull(signature);
+    this.expiry = Preconditions.checkNotNull(expiry);
+    this.salt = Preconditions.checkNotNull(salt);
+    this.isPreviewSigned = isPreviewSigned;
+
+
+    //this.isValid = EncryptionUtils.verifySignature(EncryptionUtils.SHA1_WITH_RSA, signer,
+    //        signature, salt, EncryptionUtils.longToBigEndianByteArray(
+    //                sender.getMostSignificantBits(), sender.getLeastSignificantBits()
+    //        ), Longs.toByteArray(expiry.getEpochSecond()), message.getBytes(StandardCharsets.UTF_8));
+  }
+
+  @Override
+  public PublicKey getSigner() {
+    return signer;
+  }
+
+  @Override
+  public Instant getExpiryTemporal() {
+    return expiry;
+  }
+
+  @Override
+  public @Nullable byte[] getSignature() {
+    return signature;
+  }
+
+  //@Override
+  //public boolean isSignatureValid() {
+  //  return isValid;
+  //}
+
+  @Override
+  public String getMessage() {
+    return message;
+  }
+
+  @Override
+  public UUID getSignerUuid() {
+    return sender;
+  }
+
+  @Override
+  public boolean isPreviewSigned() {
+    return isPreviewSigned;
+  }
+
+  @Override
+  public byte[] getSalt() {
+    return salt;
+  }
+
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -21,7 +21,9 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.velocitypowered.proxy.protocol.util.NettyPreconditions.checkFrame;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.proxy.crypto.IdentifiedKeyImpl;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.util.VelocityLegacyHoverEventSerializer;
 import com.velocitypowered.proxy.util.except.QuietDecoderException;
@@ -59,7 +61,7 @@ public enum ProtocolUtils {
           .legacyHoverEventSerializer(VelocityLegacyHoverEventSerializer.INSTANCE)
           .build();
 
-  private static final int DEFAULT_MAX_STRING_SIZE = 65536; // 64KiB
+  public static final int DEFAULT_MAX_STRING_SIZE = 65536; // 64KiB
   private static final QuietDecoderException BAD_VARINT_CACHED =
       new QuietDecoderException("Bad VarInt decoded");
   private static final int[] VARINT_EXACT_BYTE_LENGTHS = new int[33];
@@ -537,6 +539,31 @@ public enum ProtocolUtils {
     return PRE_1_16_SERIALIZER;
   }
 
+  /**
+   * Writes a players {@link IdentifiedKey} to the buffer.
+   *
+   * @param buf the buffer
+   * @param playerKey the key to write
+   */
+  public static void writePlayerKey(ByteBuf buf, IdentifiedKey playerKey) {
+    buf.writeLong(playerKey.getExpiryTemporal().toEpochMilli());
+    ProtocolUtils.writeByteArray(buf, playerKey.getSignedPublicKey().getEncoded());
+    ProtocolUtils.writeByteArray(buf, playerKey.getSignature());
+  }
+
+  /**
+   * Reads a players {@link IdentifiedKey} from the buffer.
+   *
+   * @param buf the buffer
+   * @return the key
+   */
+  public static IdentifiedKey readPlayerKey(ByteBuf buf) {
+    long expiry = buf.readLong();
+    byte[] key = ProtocolUtils.readByteArray(buf);
+    byte[] signature = ProtocolUtils.readByteArray(buf, 4096);
+    return new IdentifiedKeyImpl(key, expiry, signature);
+  }
+
   public enum Direction {
     SERVERBOUND,
     CLIENTBOUND;

proxy/src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java

@@ -28,6 +28,8 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_16_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_16_4;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_17;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_18;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_18_2;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_19;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_7_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_8;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9;
@@ -39,7 +41,6 @@ import static com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommands;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
-import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.EncryptionRequest;
@@ -63,6 +64,10 @@ import com.velocitypowered.proxy.protocol.packet.StatusRequest;
 import com.velocitypowered.proxy.protocol.packet.StatusResponse;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteRequest;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
+import com.velocitypowered.proxy.protocol.packet.chat.LegacyChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerChat;
+import com.velocitypowered.proxy.protocol.packet.chat.PlayerCommand;
+import com.velocitypowered.proxy.protocol.packet.chat.SystemChat;
 import com.velocitypowered.proxy.protocol.packet.title.LegacyTitlePacket;
 import com.velocitypowered.proxy.protocol.packet.title.TitleActionbarPacket;
 import com.velocitypowered.proxy.protocol.packet.title.TitleClearPacket;
@@ -114,19 +119,25 @@ public enum StateRegistry {
           map(0x02, MINECRAFT_1_12, false),
           map(0x01, MINECRAFT_1_12_1, false),
           map(0x05, MINECRAFT_1_13, false),
-          map(0x06, MINECRAFT_1_14, false));
-      serverbound.register(Chat.class, Chat::new,
+          map(0x06, MINECRAFT_1_14, false),
+          map(0x08, MINECRAFT_1_19, false));
+      serverbound.register(LegacyChat.class, LegacyChat::new,
           map(0x01, MINECRAFT_1_7_2, false),
           map(0x02, MINECRAFT_1_9, false),
           map(0x03, MINECRAFT_1_12, false),
           map(0x02, MINECRAFT_1_12_1, false),
-          map(0x03, MINECRAFT_1_14, false));
+          map(0x03, MINECRAFT_1_14, MINECRAFT_1_18_2, false));
+      serverbound.register(PlayerCommand.class, PlayerCommand::new,
+          map(0x03, MINECRAFT_1_19, false));
+      serverbound.register(PlayerChat.class, PlayerChat::new,
+          map(0x04, MINECRAFT_1_19, false));
       serverbound.register(ClientSettings.class, ClientSettings::new,
           map(0x15, MINECRAFT_1_7_2, false),
           map(0x04, MINECRAFT_1_9, false),
           map(0x05, MINECRAFT_1_12, false),
           map(0x04, MINECRAFT_1_12_1, false),
-          map(0x05, MINECRAFT_1_14, false));
+          map(0x05, MINECRAFT_1_14, false),
+          map(0x07, MINECRAFT_1_19, false));
       serverbound.register(PluginMessage.class, PluginMessage::new,
           map(0x17, MINECRAFT_1_7_2, false),
           map(0x09, MINECRAFT_1_9, false),
@@ -134,7 +145,8 @@ public enum StateRegistry {
           map(0x09, MINECRAFT_1_12_1, false),
           map(0x0A, MINECRAFT_1_13, false),
           map(0x0B, MINECRAFT_1_14, false),
-          map(0x0A, MINECRAFT_1_17, false));
+          map(0x0A, MINECRAFT_1_17, false),
+          map(0x0C, MINECRAFT_1_19, false));
       serverbound.register(KeepAlive.class, KeepAlive::new,
           map(0x00, MINECRAFT_1_7_2, false),
           map(0x0B, MINECRAFT_1_9, false),
@@ -143,7 +155,8 @@ public enum StateRegistry {
           map(0x0E, MINECRAFT_1_13, false),
           map(0x0F, MINECRAFT_1_14, false),
           map(0x10, MINECRAFT_1_16, false),
-          map(0x0F, MINECRAFT_1_17, false));
+          map(0x0F, MINECRAFT_1_17, false),
+          map(0x11, MINECRAFT_1_19, false));
       serverbound.register(ResourcePackResponse.class, ResourcePackResponse::new,
           map(0x19, MINECRAFT_1_8, false),
           map(0x16, MINECRAFT_1_9, false),
@@ -151,20 +164,22 @@ public enum StateRegistry {
           map(0x1D, MINECRAFT_1_13, false),
           map(0x1F, MINECRAFT_1_14, false),
           map(0x20, MINECRAFT_1_16, false),
-          map(0x21, MINECRAFT_1_16_2, false));
+          map(0x21, MINECRAFT_1_16_2, false),
+          map(0x23, MINECRAFT_1_19, false));
 
       clientbound.register(BossBar.class, BossBar::new,
           map(0x0C, MINECRAFT_1_9, false),
           map(0x0D, MINECRAFT_1_15, false),
           map(0x0C, MINECRAFT_1_16, false),
-          map(0x0D, MINECRAFT_1_17, false));
-      clientbound.register(Chat.class, Chat::new,
+          map(0x0D, MINECRAFT_1_17, false),
+          map(0x0A, MINECRAFT_1_19, false));
+      clientbound.register(LegacyChat.class, LegacyChat::new,
           map(0x02, MINECRAFT_1_7_2, true),
           map(0x0F, MINECRAFT_1_9, true),
           map(0x0E, MINECRAFT_1_13, true),
           map(0x0F, MINECRAFT_1_15, true),
           map(0x0E, MINECRAFT_1_16, true),
-          map(0x0F, MINECRAFT_1_17, true));
+          map(0x0F, MINECRAFT_1_17, MINECRAFT_1_18_2, true));
       clientbound.register(TabCompleteResponse.class, TabCompleteResponse::new,
           map(0x3A, MINECRAFT_1_7_2, false),
           map(0x0E, MINECRAFT_1_9, false),
@@ -172,13 +187,15 @@ public enum StateRegistry {
           map(0x11, MINECRAFT_1_15, false),
           map(0x10, MINECRAFT_1_16, false),
           map(0x0F, MINECRAFT_1_16_2, false),
-          map(0x11, MINECRAFT_1_17, false));
+          map(0x11, MINECRAFT_1_17, false),
+          map(0x0E, MINECRAFT_1_19, false));
       clientbound.register(AvailableCommands.class, AvailableCommands::new,
           map(0x11, MINECRAFT_1_13, false),
           map(0x12, MINECRAFT_1_15, false),
           map(0x11, MINECRAFT_1_16, false),
           map(0x10, MINECRAFT_1_16_2, false),
-          map(0x12, MINECRAFT_1_17, false));
+          map(0x12, MINECRAFT_1_17, false),
+          map(0x0F, MINECRAFT_1_19, false));
       clientbound.register(PluginMessage.class, PluginMessage::new,
           map(0x3F, MINECRAFT_1_7_2, false),
           map(0x18, MINECRAFT_1_9, false),
@@ -187,7 +204,8 @@ public enum StateRegistry {
           map(0x19, MINECRAFT_1_15, false),
           map(0x18, MINECRAFT_1_16, false),
           map(0x17, MINECRAFT_1_16_2, false),
-          map(0x18, MINECRAFT_1_17, false));
+          map(0x18, MINECRAFT_1_17, false),
+          map(0x15, MINECRAFT_1_19, false));
       clientbound.register(Disconnect.class, Disconnect::new,
           map(0x40, MINECRAFT_1_7_2, false),
           map(0x1A, MINECRAFT_1_9, false),
@@ -196,7 +214,8 @@ public enum StateRegistry {
           map(0x1B, MINECRAFT_1_15, false),
           map(0x1A, MINECRAFT_1_16, false),
           map(0x19, MINECRAFT_1_16_2, false),
-          map(0x1A, MINECRAFT_1_17, false));
+          map(0x1A, MINECRAFT_1_17, false),
+          map(0x17, MINECRAFT_1_19, false));
       clientbound.register(KeepAlive.class, KeepAlive::new,
           map(0x00, MINECRAFT_1_7_2, false),
           map(0x1F, MINECRAFT_1_9, false),
@@ -205,7 +224,8 @@ public enum StateRegistry {
           map(0x21, MINECRAFT_1_15, false),
           map(0x20, MINECRAFT_1_16, false),
           map(0x1F, MINECRAFT_1_16_2, false),
-          map(0x21, MINECRAFT_1_17, false));
+          map(0x21, MINECRAFT_1_17, false),
+          map(0x1E, MINECRAFT_1_19, false));
       clientbound.register(JoinGame.class, JoinGame::new,
           map(0x01, MINECRAFT_1_7_2, false),
           map(0x23, MINECRAFT_1_9, false),
@@ -214,7 +234,8 @@ public enum StateRegistry {
           map(0x26, MINECRAFT_1_15, false),
           map(0x25, MINECRAFT_1_16, false),
           map(0x24, MINECRAFT_1_16_2, false),
-          map(0x26, MINECRAFT_1_17, false));
+          map(0x26, MINECRAFT_1_17, false),
+          map(0x23, MINECRAFT_1_19, false));
       clientbound.register(Respawn.class, Respawn::new,
           map(0x07, MINECRAFT_1_7_2, true),
           map(0x33, MINECRAFT_1_9, true),
@@ -225,7 +246,8 @@ public enum StateRegistry {
           map(0x3B, MINECRAFT_1_15, true),
           map(0x3A, MINECRAFT_1_16, true),
           map(0x39, MINECRAFT_1_16_2, true),
-          map(0x3D, MINECRAFT_1_17, true));
+          map(0x3D, MINECRAFT_1_17, true),
+          map(0x3B, MINECRAFT_1_19, true));
       clientbound.register(ResourcePackRequest.class, ResourcePackRequest::new,
           map(0x48, MINECRAFT_1_8, false),
           map(0x32, MINECRAFT_1_9, false),
@@ -236,7 +258,8 @@ public enum StateRegistry {
           map(0x3A, MINECRAFT_1_15, false),
           map(0x39, MINECRAFT_1_16, false),
           map(0x38, MINECRAFT_1_16_2, false),
-          map(0x3C, MINECRAFT_1_17, false));
+          map(0x3C, MINECRAFT_1_17, false),
+          map(0x3A, MINECRAFT_1_19, false));
       clientbound.register(HeaderAndFooter.class, HeaderAndFooter::new,
           map(0x47, MINECRAFT_1_8, true),
           map(0x48, MINECRAFT_1_9, true),
@@ -248,7 +271,8 @@ public enum StateRegistry {
           map(0x54, MINECRAFT_1_15, true),
           map(0x53, MINECRAFT_1_16, true),
           map(0x5E, MINECRAFT_1_17, true),
-          map(0x5F, MINECRAFT_1_18, true));
+          map(0x5F, MINECRAFT_1_18, true),
+          map(0x60, MINECRAFT_1_19, true));
       clientbound.register(LegacyTitlePacket.class, LegacyTitlePacket::new,
           map(0x45, MINECRAFT_1_8, true),
           map(0x45, MINECRAFT_1_9, true),
@@ -265,12 +289,14 @@ public enum StateRegistry {
           map(0x59, MINECRAFT_1_17, true),
           map(0x5A, MINECRAFT_1_18, true));
       clientbound.register(TitleActionbarPacket.class, TitleActionbarPacket::new,
-          map(0x41, MINECRAFT_1_17, true));
+          map(0x41, MINECRAFT_1_17, true),
+          map(0x40, MINECRAFT_1_19, true));
       clientbound.register(TitleTimesPacket.class, TitleTimesPacket::new,
           map(0x5A, MINECRAFT_1_17, true),
           map(0x5B, MINECRAFT_1_18, true));
       clientbound.register(TitleClearPacket.class, TitleClearPacket::new,
-          map(0x10, MINECRAFT_1_17, true));
+          map(0x10, MINECRAFT_1_17, true),
+          map(0x0D, MINECRAFT_1_19, true));
       clientbound.register(PlayerListItem.class, PlayerListItem::new,
           map(0x38, MINECRAFT_1_7_2, false),
           map(0x2D, MINECRAFT_1_9, false),
@@ -280,7 +306,10 @@ public enum StateRegistry {
           map(0x34, MINECRAFT_1_15, false),
           map(0x33, MINECRAFT_1_16, false),
           map(0x32, MINECRAFT_1_16_2, false),
-          map(0x36, MINECRAFT_1_17, false));
+          map(0x36, MINECRAFT_1_17, false),
+          map(0x34, MINECRAFT_1_19, false));
+      clientbound.register(SystemChat.class, SystemChat::new,
+          map(0x5F, MINECRAFT_1_19, true));
     }
   },
   LOGIN {

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/AvailableCommands.java

@@ -83,7 +83,7 @@ public class AvailableCommands implements MinecraftPacket {
     int commands = ProtocolUtils.readVarInt(buf);
     WireNode[] wireNodes = new WireNode[commands];
     for (int i = 0; i < commands; i++) {
-      wireNodes[i] = deserializeNode(buf, i);
+      wireNodes[i] = deserializeNode(buf, i, protocolVersion);
     }
 
     // Iterate over the deserialized nodes and attempt to form a graph. We also resolve any cycles
@@ -130,13 +130,13 @@ public class AvailableCommands implements MinecraftPacket {
     // Now serialize the children.
     ProtocolUtils.writeVarInt(buf, idMappings.size());
     for (CommandNode<CommandSource> child : idMappings.keySet()) {
-      serializeNode(child, buf, idMappings);
+      serializeNode(child, buf, idMappings, protocolVersion);
     }
     ProtocolUtils.writeVarInt(buf, idMappings.getInt(rootNode));
   }
 
   private static void serializeNode(CommandNode<CommandSource> node, ByteBuf buf,
-      Object2IntMap<CommandNode<CommandSource>> idMappings) {
+      Object2IntMap<CommandNode<CommandSource>> idMappings, ProtocolVersion protocolVersion) {
     byte flags = 0;
     if (node.getRedirect() != null) {
       flags |= FLAG_IS_REDIRECT;
@@ -168,7 +168,7 @@ public class AvailableCommands implements MinecraftPacket {
     if (node instanceof ArgumentCommandNode<?, ?>) {
       ProtocolUtils.writeString(buf, node.getName());
       ArgumentPropertyRegistry.serialize(buf,
-              ((ArgumentCommandNode<CommandSource, ?>) node).getType());
+              ((ArgumentCommandNode<CommandSource, ?>) node).getType(), protocolVersion);
 
       if (((ArgumentCommandNode<CommandSource, ?>) node).getCustomSuggestions() != null) {
         SuggestionProvider<CommandSource> provider = ((ArgumentCommandNode<CommandSource, ?>) node)
@@ -189,7 +189,7 @@ public class AvailableCommands implements MinecraftPacket {
     return handler.handle(this);
   }
 
-  private static WireNode deserializeNode(ByteBuf buf, int idx) {
+  private static WireNode deserializeNode(ByteBuf buf, int idx, ProtocolVersion version) {
     byte flags = buf.readByte();
     int[] children = ProtocolUtils.readIntegerArray(buf);
     int redirectTo = -1;
@@ -205,14 +205,13 @@ public class AvailableCommands implements MinecraftPacket {
             .literal(ProtocolUtils.readString(buf)));
       case NODE_TYPE_ARGUMENT:
         String name = ProtocolUtils.readString(buf);
-        ArgumentType<?> argumentType = ArgumentPropertyRegistry.deserialize(buf);
+        ArgumentType<?> argumentType = ArgumentPropertyRegistry.deserialize(buf, version);
 
         RequiredArgumentBuilder<CommandSource, ?> argumentBuilder = RequiredArgumentBuilder
             .argument(name, argumentType);
         if ((flags & FLAG_HAS_SUGGESTIONS) != 0) {
           argumentBuilder.suggests(new ProtocolSuggestionProvider(ProtocolUtils.readString(buf)));
         }
-
         return new WireNode(idx, flags, children, redirectTo, argumentBuilder);
       default:
         throw new IllegalArgumentException("Unknown node type " + (flags & FLAG_NODE_TYPE));

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/EncryptionResponse.java

@@ -24,13 +24,19 @@ import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
+import com.velocitypowered.proxy.util.except.QuietDecoderException;
 import io.netty.buffer.ByteBuf;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import java.util.Arrays;
 
 public class EncryptionResponse implements MinecraftPacket {
 
+  private final static QuietDecoderException NO_SALT = new QuietDecoderException("Encryption response didn't contain salt");
+
   private byte[] sharedSecret = EMPTY_BYTE_ARRAY;
   private byte[] verifyToken = EMPTY_BYTE_ARRAY;
+  private @Nullable Long salt;
 
   public byte[] getSharedSecret() {
     return sharedSecret.clone();
@@ -40,6 +46,13 @@ public class EncryptionResponse implements MinecraftPacket {
     return verifyToken.clone();
   }
 
+  public long getSalt() {
+    if (salt == null) {
+      throw NO_SALT;
+    }
+    return salt;
+  }
+
   @Override
   public String toString() {
     return "EncryptionResponse{"
@@ -52,7 +65,14 @@ public class EncryptionResponse implements MinecraftPacket {
   public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       this.sharedSecret = ProtocolUtils.readByteArray(buf, 128);
-      this.verifyToken = ProtocolUtils.readByteArray(buf, 128);
+
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0
+              && !buf.readBoolean()) {
+        salt = buf.readLong();
+      }
+
+      this.verifyToken = ProtocolUtils.readByteArray(buf,
+              version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0 ? 256 : 128);
     } else {
       this.sharedSecret = ProtocolUtils.readByteArray17(buf);
       this.verifyToken = ProtocolUtils.readByteArray17(buf);
@@ -63,6 +83,14 @@ public class EncryptionResponse implements MinecraftPacket {
   public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       ProtocolUtils.writeByteArray(buf, sharedSecret);
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+        if (salt != null) {
+          buf.writeBoolean(false);
+          buf.writeLong(salt);
+        } else  {
+          buf.writeBoolean(true);
+        }
+      }
       ProtocolUtils.writeByteArray(buf, verifyToken);
     } else {
       ProtocolUtils.writeByteArray17(sharedSecret, buf, false);
@@ -79,11 +107,22 @@ public class EncryptionResponse implements MinecraftPacket {
   public int expectedMaxLength(ByteBuf buf, Direction direction, ProtocolVersion version) {
     // It turns out these come out to the same length, whether we're talking >=1.8 or not.
     // The length prefix always winds up being 2 bytes.
-    return 260;
+    int base = 256 + 2 + 2;
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      // Verify token is twice as long on 1.19+
+      // Additional 1 byte for left <> right and 8 bytes for salt
+      base += 128 + 8 + 1;
+    }
+    return base;
   }
 
   @Override
   public int expectedMinLength(ByteBuf buf, Direction direction, ProtocolVersion version) {
-    return expectedMaxLength(buf, direction, version);
+    int base = expectedMaxLength(buf, direction, version);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      // These are "optional"
+      base -= 128 + 8;
+    }
+    return base;
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/JoinGame.java

@@ -25,6 +25,7 @@ import com.velocitypowered.proxy.connection.registry.DimensionInfo;
 import com.velocitypowered.proxy.connection.registry.DimensionRegistry;
 import com.velocitypowered.proxy.protocol.*;
 import io.netty.buffer.ByteBuf;
+import it.unimi.dsi.fastutil.Pair;
 import net.kyori.adventure.nbt.BinaryTagIO;
 import net.kyori.adventure.nbt.BinaryTagTypes;
 import net.kyori.adventure.nbt.CompoundBinaryTag;
@@ -33,7 +34,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class JoinGame implements MinecraftPacket {
 
-  private static final BinaryTagIO.Reader JOINGAME_READER = BinaryTagIO.reader(2 * 1024 * 1024);
+  private static final BinaryTagIO.Reader JOINGAME_READER = BinaryTagIO.reader(4 * 1024 * 1024);
   private int entityId;
   private short gamemode;
   private int dimension;
@@ -51,6 +52,8 @@ public class JoinGame implements MinecraftPacket {
   private short previousGamemode; // 1.16+
   private CompoundBinaryTag biomeRegistry; // 1.16.2+
   private int simulationDistance; // 1.18+
+  private @Nullable Pair<String, Long> lastDeathPosition;
+  private CompoundBinaryTag chatTypeRegistry; // placeholder, 1.19+
 
   public int getEntityId() {
     return entityId;
@@ -172,6 +175,22 @@ public class JoinGame implements MinecraftPacket {
     this.simulationDistance = simulationDistance;
   }
 
+  public Pair<String, Long> getLastDeathPosition() {
+    return lastDeathPosition;
+  }
+
+  public void setLastDeathPosition(Pair<String, Long> lastDeathPosition) {
+    this.lastDeathPosition = lastDeathPosition;
+  }
+
+  public CompoundBinaryTag getChatTypeRegistry() {
+    return chatTypeRegistry;
+  }
+
+  public void setChatTypeRegistry(CompoundBinaryTag chatTypeRegistry) {
+    this.chatTypeRegistry = chatTypeRegistry;
+  }
+
   @Override
   public String toString() {
     return "JoinGame{"
@@ -188,6 +207,7 @@ public class JoinGame implements MinecraftPacket {
         + ", dimensionInfo='" + dimensionInfo + '\''
         + ", previousGamemode=" + previousGamemode
         + ", simulationDistance=" + simulationDistance
+        + ", lastDeathPosition='" + lastDeathPosition + '\''
         + '}';
   }
 
@@ -253,6 +273,7 @@ public class JoinGame implements MinecraftPacket {
       dimensionRegistryContainer = registryContainer.getCompound("minecraft:dimension_type")
           .getList("value", BinaryTagTypes.COMPOUND);
       this.biomeRegistry = registryContainer.getCompound("minecraft:worldgen/biome");
+      this.chatTypeRegistry = registryContainer.getCompound("minecraft:chat_type");
     } else {
       dimensionRegistryContainer = registryContainer.getList("dimension",
           BinaryTagTypes.COMPOUND);
@@ -263,7 +284,8 @@ public class JoinGame implements MinecraftPacket {
 
     String dimensionIdentifier;
     String levelName = null;
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0
+            && version.compareTo(ProtocolVersion.MINECRAFT_1_19) < 0) {
       CompoundBinaryTag currentDimDataTag = ProtocolUtils.readCompoundTag(buf, JOINGAME_READER);
       dimensionIdentifier = ProtocolUtils.readString(buf);
       this.currentDimensionData = DimensionData.decodeBaseCompoundTag(currentDimDataTag, version)
@@ -290,6 +312,10 @@ public class JoinGame implements MinecraftPacket {
     boolean isDebug = buf.readBoolean();
     boolean isFlat = buf.readBoolean();
     this.dimensionInfo = new DimensionInfo(dimensionIdentifier, levelName, isFlat, isDebug);
+    // optional death location
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0 && buf.readBoolean()) {
+      this.lastDeathPosition = Pair.of(ProtocolUtils.readString(buf), buf.readLong());
+    }
   }
 
   @Override
@@ -356,11 +382,13 @@ public class JoinGame implements MinecraftPacket {
       dimensionRegistryEntry.put("value", encodedDimensionRegistry);
       registryContainer.put("minecraft:dimension_type", dimensionRegistryEntry.build());
       registryContainer.put("minecraft:worldgen/biome", biomeRegistry);
+      registryContainer.put("minecraft:chat_type", chatTypeRegistry);
     } else {
       registryContainer.put("dimension", encodedDimensionRegistry);
     }
     ProtocolUtils.writeCompoundTag(buf, registryContainer.build());
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0
+            && version.compareTo(ProtocolVersion.MINECRAFT_1_19) < 0) {
       ProtocolUtils.writeCompoundTag(buf, currentDimensionData.serializeDimensionDetails());
       ProtocolUtils.writeString(buf, dimensionInfo.getRegistryIdentifier());
     } else {
@@ -382,6 +410,17 @@ public class JoinGame implements MinecraftPacket {
     buf.writeBoolean(showRespawnScreen);
     buf.writeBoolean(dimensionInfo.isDebugType());
     buf.writeBoolean(dimensionInfo.isFlat());
+
+    // optional death location
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (lastDeathPosition != null) {
+        buf.writeBoolean(true);
+        ProtocolUtils.writeString(buf, lastDeathPosition.key());
+        buf.writeLong(lastDeathPosition.value());
+      } else {
+        buf.writeBoolean(false);
+      }
+    }
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/PlayerListItem.java

@@ -19,6 +19,7 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
@@ -74,6 +75,12 @@ public class PlayerListItem implements MinecraftPacket {
             item.setGameMode(ProtocolUtils.readVarInt(buf));
             item.setLatency(ProtocolUtils.readVarInt(buf));
             item.setDisplayName(readOptionalComponent(buf, version));
+
+            if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+              if (buf.readBoolean()) {
+                item.setPlayerKey(ProtocolUtils.readPlayerKey(buf));
+              }
+            }
             break;
           case UPDATE_GAMEMODE:
             item.setGameMode(ProtocolUtils.readVarInt(buf));
@@ -124,8 +131,15 @@ public class PlayerListItem implements MinecraftPacket {
             ProtocolUtils.writeProperties(buf, item.getProperties());
             ProtocolUtils.writeVarInt(buf, item.getGameMode());
             ProtocolUtils.writeVarInt(buf, item.getLatency());
-
             writeDisplayName(buf, item.getDisplayName(), version);
+            if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+              if (item.getPlayerKey() != null) {
+                buf.writeBoolean(true);
+                ProtocolUtils.writePlayerKey(buf, item.getPlayerKey());
+              } else {
+                buf.writeBoolean(false);
+              }
+            }
             break;
           case UPDATE_GAMEMODE:
             ProtocolUtils.writeVarInt(buf, item.getGameMode());
@@ -181,6 +195,7 @@ public class PlayerListItem implements MinecraftPacket {
     private int gameMode;
     private int latency;
     private @Nullable Component displayName;
+    private @Nullable IdentifiedKey playerKey;
 
     public Item() {
       uuid = null;
@@ -196,6 +211,7 @@ public class PlayerListItem implements MinecraftPacket {
           .setProperties(entry.getProfile().getProperties())
           .setLatency(entry.getLatency())
           .setGameMode(entry.getGameMode())
+          .setPlayerKey(entry.getIdentifiedKey())
           .setDisplayName(entry.getDisplayNameComponent().orElse(null));
     }
 
@@ -247,5 +263,14 @@ public class PlayerListItem implements MinecraftPacket {
       this.displayName = displayName;
       return this;
     }
+
+    public Item setPlayerKey(IdentifiedKey playerKey) {
+      this.playerKey = playerKey;
+      return this;
+    }
+
+    public IdentifiedKey getPlayerKey() {
+      return playerKey;
+    }
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/Respawn.java

@@ -24,8 +24,10 @@ import com.velocitypowered.proxy.connection.registry.DimensionInfo;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
+import it.unimi.dsi.fastutil.Pair;
 import net.kyori.adventure.nbt.BinaryTagIO;
 import net.kyori.adventure.nbt.CompoundBinaryTag;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class Respawn implements MinecraftPacket {
 
@@ -38,13 +40,14 @@ public class Respawn implements MinecraftPacket {
   private DimensionInfo dimensionInfo; // 1.16-1.16.1
   private short previousGamemode; // 1.16+
   private DimensionData currentDimensionData; // 1.16.2+
+  private @Nullable Pair<String, Long> lastDeathPosition; // 1.19+
 
   public Respawn() {
   }
 
   public Respawn(int dimension, long partialHashedSeed, short difficulty, short gamemode,
       String levelType, boolean shouldKeepPlayerData, DimensionInfo dimensionInfo,
-      short previousGamemode, DimensionData currentDimensionData) {
+      short previousGamemode, DimensionData currentDimensionData, @Nullable Pair<String, Long> lastDeathPosition) {
     this.dimension = dimension;
     this.partialHashedSeed = partialHashedSeed;
     this.difficulty = difficulty;
@@ -54,6 +57,7 @@ public class Respawn implements MinecraftPacket {
     this.dimensionInfo = dimensionInfo;
     this.previousGamemode = previousGamemode;
     this.currentDimensionData = currentDimensionData;
+    this.lastDeathPosition = lastDeathPosition;
   }
 
   public int getDimension() {
@@ -112,6 +116,14 @@ public class Respawn implements MinecraftPacket {
     this.previousGamemode = previousGamemode;
   }
 
+  public void setLastDeathPosition(Pair<String, Long> lastDeathPosition) {
+    this.lastDeathPosition = lastDeathPosition;
+  }
+
+  public Pair<String, Long> getLastDeathPosition() {
+    return lastDeathPosition;
+  }
+
   @Override
   public String toString() {
     return "Respawn{"
@@ -133,7 +145,8 @@ public class Respawn implements MinecraftPacket {
     String dimensionIdentifier = null;
     String levelName = null;
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
-      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0) {
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0
+              && version.compareTo(ProtocolVersion.MINECRAFT_1_19) < 0) {
         CompoundBinaryTag dimDataTag = ProtocolUtils.readCompoundTag(buf, BinaryTagIO.reader());
         dimensionIdentifier = ProtocolUtils.readString(buf);
         this.currentDimensionData = DimensionData.decodeBaseCompoundTag(dimDataTag, version)
@@ -161,12 +174,16 @@ public class Respawn implements MinecraftPacket {
     } else {
       this.levelType = ProtocolUtils.readString(buf, 16);
     }
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0 && buf.readBoolean()) {
+      this.lastDeathPosition = Pair.of(ProtocolUtils.readString(buf), buf.readLong());
+    }
   }
 
   @Override
   public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
-      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0) {
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16_2) >= 0
+              && version.compareTo(ProtocolVersion.MINECRAFT_1_19) < 0) {
         ProtocolUtils.writeCompoundTag(buf, currentDimensionData.serializeDimensionDetails());
         ProtocolUtils.writeString(buf, dimensionInfo.getRegistryIdentifier());
       } else {
@@ -191,6 +208,17 @@ public class Respawn implements MinecraftPacket {
     } else {
       ProtocolUtils.writeString(buf, levelType);
     }
+
+    // optional death location
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (lastDeathPosition != null) {
+        buf.writeBoolean(true);
+        ProtocolUtils.writeString(buf, lastDeathPosition.key());
+        buf.writeLong(lastDeathPosition.value());
+      } else {
+        buf.writeBoolean(false);
+      }
+    }
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/ServerLogin.java

@@ -19,6 +19,7 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
@@ -32,11 +33,12 @@ public class ServerLogin implements MinecraftPacket {
   private static final QuietDecoderException EMPTY_USERNAME = new QuietDecoderException("Empty username!");
 
   private @Nullable String username;
+  private @Nullable IdentifiedKey playerKey; // Introduced in 1.19
 
   public ServerLogin() {
   }
 
-  public ServerLogin(String username) {
+  public ServerLogin(String username, @Nullable IdentifiedKey playerKey) {
     this.username = Preconditions.checkNotNull(username, "username");
   }
 
@@ -47,10 +49,19 @@ public class ServerLogin implements MinecraftPacket {
     return username;
   }
 
+  public IdentifiedKey getPlayerKey() {
+    return playerKey;
+  }
+
+  public void setPlayerKey(IdentifiedKey playerKey) {
+    this.playerKey = playerKey;
+  }
+
   @Override
   public String toString() {
     return "ServerLogin{"
         + "username='" + username + '\''
+        + "playerKey='" + playerKey + '\''
         + '}';
   }
 
@@ -60,6 +71,12 @@ public class ServerLogin implements MinecraftPacket {
     if (username.isEmpty()) {
       throw EMPTY_USERNAME;
     }
+
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (buf.readBoolean()) {
+        playerKey = ProtocolUtils.readPlayerKey(buf);
+      }
+    }
   }
 
   @Override
@@ -68,13 +85,27 @@ public class ServerLogin implements MinecraftPacket {
       throw new IllegalStateException("No username found!");
     }
     ProtocolUtils.writeString(buf, username);
+
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (playerKey != null) {
+        buf.writeBoolean(true);
+        ProtocolUtils.writePlayerKey(buf, playerKey);
+      } else {
+        buf.writeBoolean(false);
+      }
+    }
   }
 
   @Override
   public int expectedMaxLength(ByteBuf buf, Direction direction, ProtocolVersion version) {
     // Accommodate the rare (but likely malicious) use of UTF-8 usernames, since it is technically
     // legal on the protocol level.
-    return 1 + (16 * 4);
+    int base = 1 + (16 * 4);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      return -1;
+      //TODO: ## 19
+    }
+    return base;
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/ServerLoginSuccess.java

@@ -18,11 +18,14 @@
 package com.velocitypowered.proxy.protocol.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
+
+import java.util.List;
 import java.util.UUID;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -30,6 +33,7 @@ public class ServerLoginSuccess implements MinecraftPacket {
 
   private @Nullable UUID uuid;
   private @Nullable String username;
+  private @Nullable List<GameProfile.Property> properties;
 
   public UUID getUuid() {
     if (uuid == null) {
@@ -53,17 +57,28 @@ public class ServerLoginSuccess implements MinecraftPacket {
     this.username = username;
   }
 
+  public List<GameProfile.Property> getProperties() {
+    return properties;
+  }
+
+  public void setProperties(List<GameProfile.Property> properties) {
+    this.properties = properties;
+  }
+
   @Override
   public String toString() {
     return "ServerLoginSuccess{"
         + "uuid=" + uuid
         + ", username='" + username + '\''
+        + ", properties='" + properties + '\''
         + '}';
   }
 
   @Override
   public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      uuid = ProtocolUtils.readUuid(buf);
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
       uuid = ProtocolUtils.readUuidIntArray(buf);
     } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_7_6) >= 0) {
       uuid = UUID.fromString(ProtocolUtils.readString(buf, 36));
@@ -71,6 +86,10 @@ public class ServerLoginSuccess implements MinecraftPacket {
       uuid = UuidUtils.fromUndashed(ProtocolUtils.readString(buf, 32));
     }
     username = ProtocolUtils.readString(buf, 16);
+
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      properties = ProtocolUtils.readProperties(buf);
+    }
   }
 
   @Override
@@ -78,7 +97,9 @@ public class ServerLoginSuccess implements MinecraftPacket {
     if (uuid == null) {
       throw new IllegalStateException("No UUID specified!");
     }
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      ProtocolUtils.writeUuid(buf, uuid);
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
       ProtocolUtils.writeUuidIntArray(buf, uuid);
     } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_7_6) >= 0) {
       ProtocolUtils.writeString(buf, uuid.toString());
@@ -89,6 +110,14 @@ public class ServerLoginSuccess implements MinecraftPacket {
       throw new IllegalStateException("No username specified!");
     }
     ProtocolUtils.writeString(buf, username);
+
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (properties == null) {
+        ProtocolUtils.writeVarInt(buf, 0);
+      } else {
+        ProtocolUtils.writeProperties(buf, properties);
+      }
+    }
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ArgumentIdentifier.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.brigadier;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.velocitypowered.api.network.ProtocolVersion;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ArgumentIdentifier {
+
+  private final String identifier;
+  private final Map<ProtocolVersion, Integer> versionById;
+
+  private ArgumentIdentifier(String identifier, VersionSet... versions) {
+    this.identifier = Preconditions.checkNotNull(identifier);
+
+    Preconditions.checkNotNull(versions);
+
+    Map<ProtocolVersion, Integer> temp = new HashMap<>();
+
+    ProtocolVersion previous = null;
+    for (int i = 0; i < versions.length; i++) {
+      VersionSet current = Preconditions.checkNotNull(versions[i]);
+
+      Preconditions.checkArgument(current.getVersion().compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0,
+              "Version too old for ID index");
+      Preconditions.checkArgument(previous == null || previous.compareTo(current.getVersion()) > 0,
+              "Invalid protocol version order");
+
+      for (ProtocolVersion v : ProtocolVersion.values()) {
+        if (v.compareTo(current.getVersion()) >= 0) {
+          temp.put(v, current.getId());
+        }
+      }
+      previous = current.getVersion();
+
+    }
+
+    this.versionById = ImmutableMap.copyOf(temp);
+  }
+
+  public String getIdentifier() {
+    return identifier;
+  }
+
+  public @Nullable Integer getIdByProtocolVersion(ProtocolVersion version) {
+    return versionById.get(Preconditions.checkNotNull(version));
+  }
+
+  public static VersionSet mapSet(ProtocolVersion version, int id) {
+    return new VersionSet(version, id);
+  }
+
+  public static ArgumentIdentifier id(String identifier, VersionSet... versions) {
+    return new ArgumentIdentifier(identifier, versions);
+  }
+
+  /**
+   * This class is purely for convenience.
+   */
+  public static class VersionSet {
+    private final ProtocolVersion version;
+    private final int id;
+
+    private VersionSet(ProtocolVersion version, int id) {
+      this.version = Preconditions.checkNotNull(version);
+      this.id = id;
+    }
+
+    public int getId() {
+      return id;
+    }
+
+    public ProtocolVersion getVersion() {
+      return version;
+    }
+
+  }
+
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ArgumentPropertyRegistry.java

@@ -17,6 +17,9 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_19;
+import static com.velocitypowered.proxy.protocol.packet.brigadier.ArgumentIdentifier.id;
+import static com.velocitypowered.proxy.protocol.packet.brigadier.ArgumentIdentifier.mapSet;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.DoubleArgumentPropertySerializer.DOUBLE;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.EmptyArgumentPropertySerializer.EMPTY;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.FloatArgumentPropertySerializer.FLOAT;
@@ -25,6 +28,7 @@ import static com.velocitypowered.proxy.protocol.packet.brigadier.LongArgumentPr
 import static com.velocitypowered.proxy.protocol.packet.brigadier.ModArgumentPropertySerializer.MOD;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.StringArgumentPropertySerializer.STRING;
 
+import com.google.common.base.Preconditions;
 import com.mojang.brigadier.arguments.ArgumentType;
 import com.mojang.brigadier.arguments.BoolArgumentType;
 import com.mojang.brigadier.arguments.DoubleArgumentType;
@@ -32,35 +36,38 @@ import com.mojang.brigadier.arguments.FloatArgumentType;
 import com.mojang.brigadier.arguments.IntegerArgumentType;
 import com.mojang.brigadier.arguments.LongArgumentType;
 import com.mojang.brigadier.arguments.StringArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.HashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class ArgumentPropertyRegistry {
   private ArgumentPropertyRegistry() {
     throw new AssertionError();
   }
 
-  private static final Map<String, ArgumentPropertySerializer<?>> byId = new HashMap<>();
+  private static final Map<ArgumentIdentifier, ArgumentPropertySerializer<?>> byIdentifier =
+          new HashMap<>();
   private static final Map<Class<? extends ArgumentType>,
       ArgumentPropertySerializer<?>> byClass = new HashMap<>();
-  private static final Map<Class<? extends ArgumentType>, String> classToId = new HashMap<>();
+  private static final Map<Class<? extends ArgumentType>, ArgumentIdentifier> classToId =
+          new HashMap<>();
 
-  private static <T extends ArgumentType<?>> void register(String identifier, Class<T> klazz,
-      ArgumentPropertySerializer<T> serializer) {
-    byId.put(identifier, serializer);
+  private static <T extends ArgumentType<?>> void register(ArgumentIdentifier identifier,
+          Class<T> klazz, ArgumentPropertySerializer<T> serializer) {
+    byIdentifier.put(identifier, serializer);
     byClass.put(klazz, serializer);
     classToId.put(klazz, identifier);
   }
 
-  private static <T> void empty(String identifier) {
+  private static <T> void empty(ArgumentIdentifier identifier) {
     empty(identifier, EMPTY);
   }
 
-  private static <T> void empty(String identifier, ArgumentPropertySerializer<T> serializer) {
-    byId.put(identifier, serializer);
+  private static <T> void empty(ArgumentIdentifier identifier,
+                                ArgumentPropertySerializer<T> serializer) {
+    byIdentifier.put(identifier, serializer);
   }
 
   /**
@@ -68,13 +75,14 @@ public class ArgumentPropertyRegistry {
    * @param buf the buffer to deserialize
    * @return the deserialized {@link ArgumentType}
    */
-  public static ArgumentType<?> deserialize(ByteBuf buf) {
-    String identifier = ProtocolUtils.readString(buf);
-    ArgumentPropertySerializer<?> serializer = byId.get(identifier);
+  public static ArgumentType<?> deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
+    ArgumentIdentifier identifier = readIdentifier(buf, protocolVersion);
+
+    ArgumentPropertySerializer<?> serializer = byIdentifier.get(identifier);
     if (serializer == null) {
       throw new IllegalArgumentException("Argument type identifier " + identifier + " unknown.");
     }
-    Object result = serializer.deserialize(buf);
+    Object result = serializer.deserialize(buf, protocolVersion);
 
     if (result instanceof ArgumentType) {
       return (ArgumentType<?>) result;
@@ -88,95 +96,144 @@ public class ArgumentPropertyRegistry {
    * @param buf the buffer to serialize into
    * @param type the type to serialize
    */
-  public static void serialize(ByteBuf buf, ArgumentType<?> type) {
+  public static void serialize(ByteBuf buf, ArgumentType<?> type,
+                               ProtocolVersion protocolVersion) {
     if (type instanceof PassthroughProperty) {
       PassthroughProperty property = (PassthroughProperty) type;
-      ProtocolUtils.writeString(buf, property.getIdentifier());
+      writeIdentifier(buf, property.getIdentifier(), protocolVersion);
       if (property.getResult() != null) {
-        property.getSerializer().serialize(property.getResult(), buf);
+        property.getSerializer().serialize(property.getResult(), buf, protocolVersion);
       }
     } else if (type instanceof ModArgumentProperty) {
       ModArgumentProperty property = (ModArgumentProperty) type;
-      ProtocolUtils.writeString(buf, property.getIdentifier());
+      writeIdentifier(buf, property.getIdentifier(), protocolVersion);
       buf.writeBytes(property.getData());
     } else {
       ArgumentPropertySerializer serializer = byClass.get(type.getClass());
-      String id = classToId.get(type.getClass());
+      ArgumentIdentifier id = classToId.get(type.getClass());
       if (serializer == null || id == null) {
         throw new IllegalArgumentException("Don't know how to serialize "
             + type.getClass().getName());
       }
-      ProtocolUtils.writeString(buf, id);
-      serializer.serialize(type, buf);
+      writeIdentifier(buf, id, protocolVersion);
+      serializer.serialize(type, buf, protocolVersion);
     }
   }
 
+  /**
+   * Writes the {@link ArgumentIdentifier} to a version-specific buffer.
+   * @param buf the buffer to write to
+   * @param identifier the identifier to write
+   * @param protocolVersion the protocol version to use
+   */
+  public static void writeIdentifier(ByteBuf buf, ArgumentIdentifier identifier,
+                                 ProtocolVersion protocolVersion) {
+    if (protocolVersion.compareTo(MINECRAFT_1_19) >= 0) {
+      Integer id = identifier.getIdByProtocolVersion(protocolVersion);
+      Preconditions.checkNotNull(id, "Don't know how to serialize type " + identifier);
+
+      ProtocolUtils.writeVarInt(buf, id);
+    } else {
+      ProtocolUtils.writeString(buf, identifier.getIdentifier());
+    }
+
+  }
+
+  /**
+   * Reads the {@link ArgumentIdentifier} from a version-specific buffer.
+   * @param buf the buffer to write to
+   * @param protocolVersion the protocol version to use
+   * @return the identifier read from the buffer
+   */
+  public static ArgumentIdentifier readIdentifier(ByteBuf buf, ProtocolVersion protocolVersion) {
+    if (protocolVersion.compareTo(MINECRAFT_1_19) >= 0) {
+      int id = ProtocolUtils.readVarInt(buf);
+      for (ArgumentIdentifier i : byIdentifier.keySet()) {
+        Integer v = i.getIdByProtocolVersion(protocolVersion);
+        if (v != null && v == id) {
+          return i;
+        }
+      }
+    } else {
+      String identifier = ProtocolUtils.readString(buf);
+      for (ArgumentIdentifier i : byIdentifier.keySet()) {
+        if (i.getIdentifier().equals(identifier)) {
+          return i;
+        }
+      }
+    }
+    return null;
+  }
+
   static {
     // Base Brigadier argument types
-    register("brigadier:string", StringArgumentType.class, STRING);
-    register("brigadier:integer", IntegerArgumentType.class, INTEGER);
-    register("brigadier:float", FloatArgumentType.class, FLOAT);
-    register("brigadier:double", DoubleArgumentType.class, DOUBLE);
-    register("brigadier:bool", BoolArgumentType.class,
+    register(id("brigadier:bool", mapSet(MINECRAFT_1_19, 0)), BoolArgumentType.class,
         new ArgumentPropertySerializer<>() {
           @Override
-          public BoolArgumentType deserialize(ByteBuf buf) {
+          public BoolArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
             return BoolArgumentType.bool();
           }
 
           @Override
-          public void serialize(BoolArgumentType object, ByteBuf buf) {
+          public void serialize(BoolArgumentType object, ByteBuf buf,
+                                ProtocolVersion protocolVersion) {
 
           }
         });
-    register("brigadier:long", LongArgumentType.class, LONG);
-    register("minecraft:resource", RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
-    register("minecraft:resource_or_tag", RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
+    register(id("brigadier:float", mapSet(MINECRAFT_1_19, 1)), FloatArgumentType.class, FLOAT);
+    register(id("brigadier:double", mapSet(MINECRAFT_1_19, 2)), DoubleArgumentType.class, DOUBLE);
+    register(id("brigadier:integer", mapSet(MINECRAFT_1_19, 3)), IntegerArgumentType.class, INTEGER);
+    register(id("brigadier:long", mapSet(MINECRAFT_1_19, 4)), LongArgumentType.class, LONG);
+    register(id("brigadier:string", mapSet(MINECRAFT_1_19, 5)), StringArgumentType.class, STRING);
+
+    empty(id("minecraft:entity", mapSet(MINECRAFT_1_19, 6)), ByteArgumentPropertySerializer.BYTE);
+    empty(id("minecraft:game_profile", mapSet(MINECRAFT_1_19, 7)));
+    empty(id("minecraft:block_pos", mapSet(MINECRAFT_1_19, 8)));
+    empty(id("minecraft:column_pos", mapSet(MINECRAFT_1_19, 9)));
+    empty(id("minecraft:vec3", mapSet(MINECRAFT_1_19, 10)));
+    empty(id("minecraft:vec2", mapSet(MINECRAFT_1_19, 11)));
+    empty(id("minecraft:block_state", mapSet(MINECRAFT_1_19, 12)));
+    empty(id("minecraft:block_predicate", mapSet(MINECRAFT_1_19, 13)));
+    empty(id("minecraft:item_stack", mapSet(MINECRAFT_1_19, 14)));
+    empty(id("minecraft:item_predicate", mapSet(MINECRAFT_1_19, 15)));
+    empty(id("minecraft:color", mapSet(MINECRAFT_1_19, 16)));
+    empty(id("minecraft:component", mapSet(MINECRAFT_1_19, 17)));
+    empty(id("minecraft:message", mapSet(MINECRAFT_1_19, 18)));
+    empty(id("minecraft:nbt_compound_tag", mapSet(MINECRAFT_1_19, 19))); // added in 1.14
+    empty(id("minecraft:nbt_tag", mapSet(MINECRAFT_1_19, 20))); // added in 1.14
+    empty(id("minecraft:nbt_path", mapSet(MINECRAFT_1_19, 21)));
+    empty(id("minecraft:objective", mapSet(MINECRAFT_1_19, 22)));
+    empty(id("minecraft:objective_criteria", mapSet(MINECRAFT_1_19, 23)));
+    empty(id("minecraft:operation", mapSet(MINECRAFT_1_19, 24)));
+    empty(id("minecraft:particle", mapSet(MINECRAFT_1_19, 25)));
+    empty(id("minecraft:angle", mapSet(MINECRAFT_1_19, 26))); // added in 1.16.2
+    empty(id("minecraft:rotation", mapSet(MINECRAFT_1_19, 27)));
+    empty(id("minecraft:scoreboard_slot", mapSet(MINECRAFT_1_19, 28)));
+    empty(id("minecraft:score_holder", mapSet(MINECRAFT_1_19, 29)), ByteArgumentPropertySerializer.BYTE);
+    empty(id("minecraft:swizzle", mapSet(MINECRAFT_1_19, 30)));
+    empty(id("minecraft:team", mapSet(MINECRAFT_1_19, 31)));
+    empty(id("minecraft:item_slot", mapSet(MINECRAFT_1_19, 32)));
+    empty(id("minecraft:resource_location", mapSet(MINECRAFT_1_19, 33)));
+    empty(id("minecraft:mob_effect", mapSet(MINECRAFT_1_19, 34)));
+    empty(id("minecraft:function", mapSet(MINECRAFT_1_19, 35)));
+    empty(id("minecraft:entity_anchor", mapSet(MINECRAFT_1_19, 36)));
+    empty(id("minecraft:int_range", mapSet(MINECRAFT_1_19, 37)));
+    empty(id("minecraft:float_range", mapSet(MINECRAFT_1_19, 38)));
+    empty(id("minecraft:item_enchantment", mapSet(MINECRAFT_1_19, 39)));
+    empty(id("minecraft:entity_summon", mapSet(MINECRAFT_1_19, 40)));
+    empty(id("minecraft:dimension", mapSet(MINECRAFT_1_19, 41)));
+    empty(id("minecraft:time", mapSet(MINECRAFT_1_19, 42))); // added in 1.14
+
+    register(id("minecraft:resource_or_tag", mapSet(MINECRAFT_1_19, 43)),
+            RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
+    register(id("minecraft:resource", mapSet(MINECRAFT_1_19, 44)),
+            RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
+
+    empty(id("minecraft:uuid", mapSet(MINECRAFT_1_19, 45))); // added in 1.16
 
     // Crossstitch support
-    register("crossstitch:mod_argument", ModArgumentProperty.class, MOD);
+    register(id("crossstitch:mod_argument", mapSet(MINECRAFT_1_19, -256)), ModArgumentProperty.class, MOD);
 
-    // Minecraft argument types with extra properties
-    empty("minecraft:entity", ByteArgumentPropertySerializer.BYTE);
-    empty("minecraft:score_holder", ByteArgumentPropertySerializer.BYTE);
-
-    // Minecraft argument types
-    empty("minecraft:game_profile");
-    empty("minecraft:block_pos");
-    empty("minecraft:column_pos");
-    empty("minecraft:vec3");
-    empty("minecraft:vec2");
-    empty("minecraft:block_state");
-    empty("minecraft:block_predicate");
-    empty("minecraft:item_stack");
-    empty("minecraft:item_predicate");
-    empty("minecraft:color");
-    empty("minecraft:component");
-    empty("minecraft:message");
-    empty("minecraft:nbt");
-    empty("minecraft:nbt_compound_tag"); // added in 1.14
-    empty("minecraft:nbt_tag"); // added in 1.14
-    empty("minecraft:nbt_path");
-    empty("minecraft:objective");
-    empty("minecraft:objective_criteria");
-    empty("minecraft:operation");
-    empty("minecraft:particle");
-    empty("minecraft:rotation");
-    empty("minecraft:scoreboard_slot");
-    empty("minecraft:swizzle");
-    empty("minecraft:team");
-    empty("minecraft:item_slot");
-    empty("minecraft:resource_location");
-    empty("minecraft:mob_effect");
-    empty("minecraft:function");
-    empty("minecraft:entity_anchor");
-    empty("minecraft:item_enchantment");
-    empty("minecraft:entity_summon");
-    empty("minecraft:dimension");
-    empty("minecraft:int_range");
-    empty("minecraft:float_range");
-    empty("minecraft:time"); // added in 1.14
-    empty("minecraft:uuid"); // added in 1.16
-    empty("minecraft:angle"); // added in 1.16.2
+    empty(id("minecraft:nbt")); // No longer in 1.19+
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ArgumentPropertySerializer.java

@@ -17,11 +17,12 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public interface ArgumentPropertySerializer<T> {
-  @Nullable T deserialize(ByteBuf buf);
+  @Nullable T deserialize(ByteBuf buf, ProtocolVersion protocolVersion);
 
-  void serialize(T object, ByteBuf buf);
+  void serialize(T object, ByteBuf buf, ProtocolVersion protocolVersion);
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ByteArgumentPropertySerializer.java

@@ -17,6 +17,7 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 
 class ByteArgumentPropertySerializer implements ArgumentPropertySerializer<Byte> {
@@ -28,12 +29,12 @@ class ByteArgumentPropertySerializer implements ArgumentPropertySerializer<Byte>
   }
 
   @Override
-  public Byte deserialize(ByteBuf buf) {
+  public Byte deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     return buf.readByte();
   }
 
   @Override
-  public void serialize(Byte object, ByteBuf buf) {
+  public void serialize(Byte object, ByteBuf buf, ProtocolVersion protocolVersion) {
     buf.writeByte(object);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/DoubleArgumentPropertySerializer.java

@@ -22,6 +22,7 @@ import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumen
 import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumentPropertySerializer.getFlags;
 
 import com.mojang.brigadier.arguments.DoubleArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 
 class DoubleArgumentPropertySerializer implements ArgumentPropertySerializer<DoubleArgumentType> {
@@ -32,7 +33,7 @@ class DoubleArgumentPropertySerializer implements ArgumentPropertySerializer<Dou
   }
 
   @Override
-  public DoubleArgumentType deserialize(ByteBuf buf) {
+  public DoubleArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     byte flags = buf.readByte();
     double minimum = (flags & HAS_MINIMUM) != 0 ? buf.readDouble() : Double.MIN_VALUE;
     double maximum = (flags & HAS_MAXIMUM) != 0 ? buf.readDouble() : Double.MAX_VALUE;
@@ -40,7 +41,7 @@ class DoubleArgumentPropertySerializer implements ArgumentPropertySerializer<Dou
   }
 
   @Override
-  public void serialize(DoubleArgumentType object, ByteBuf buf) {
+  public void serialize(DoubleArgumentType object, ByteBuf buf, ProtocolVersion protocolVersion) {
     boolean hasMinimum = Double.compare(object.getMinimum(), Double.MIN_VALUE) != 0;
     boolean hasMaximum = Double.compare(object.getMaximum(), Double.MAX_VALUE) != 0;
     byte flag = getFlags(hasMinimum, hasMaximum);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/EmptyArgumentPropertySerializer.java

@@ -17,6 +17,7 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -32,12 +33,12 @@ class EmptyArgumentPropertySerializer implements ArgumentPropertySerializer<Void
   }
 
   @Override
-  public @Nullable Void deserialize(ByteBuf buf) {
+  public @Nullable Void deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     return null;
   }
 
   @Override
-  public void serialize(Void object, ByteBuf buf) {
+  public void serialize(Void object, ByteBuf buf, ProtocolVersion protocolVersion) {
 
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/FloatArgumentPropertySerializer.java

@@ -22,6 +22,7 @@ import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumen
 import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumentPropertySerializer.getFlags;
 
 import com.mojang.brigadier.arguments.FloatArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 
 class FloatArgumentPropertySerializer implements ArgumentPropertySerializer<FloatArgumentType> {
@@ -33,7 +34,7 @@ class FloatArgumentPropertySerializer implements ArgumentPropertySerializer<Floa
   }
 
   @Override
-  public FloatArgumentType deserialize(ByteBuf buf) {
+  public FloatArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     byte flags = buf.readByte();
     float minimum = (flags & HAS_MINIMUM) != 0 ? buf.readFloat() : Float.MIN_VALUE;
     float maximum = (flags & HAS_MAXIMUM) != 0 ? buf.readFloat() : Float.MAX_VALUE;
@@ -41,7 +42,7 @@ class FloatArgumentPropertySerializer implements ArgumentPropertySerializer<Floa
   }
 
   @Override
-  public void serialize(FloatArgumentType object, ByteBuf buf) {
+  public void serialize(FloatArgumentType object, ByteBuf buf, ProtocolVersion protocolVersion) {
     boolean hasMinimum = Float.compare(object.getMinimum(), Float.MIN_VALUE) != 0;
     boolean hasMaximum = Float.compare(object.getMaximum(), Float.MAX_VALUE) != 0;
     byte flag = getFlags(hasMinimum, hasMaximum);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/IntegerArgumentPropertySerializer.java

@@ -18,6 +18,7 @@
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
 import com.mojang.brigadier.arguments.IntegerArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 
 class IntegerArgumentPropertySerializer implements ArgumentPropertySerializer<IntegerArgumentType> {
@@ -32,7 +33,7 @@ class IntegerArgumentPropertySerializer implements ArgumentPropertySerializer<In
   }
 
   @Override
-  public IntegerArgumentType deserialize(ByteBuf buf) {
+  public IntegerArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     byte flags = buf.readByte();
     int minimum = (flags & HAS_MINIMUM) != 0 ? buf.readInt() : Integer.MIN_VALUE;
     int maximum = (flags & HAS_MAXIMUM) != 0 ? buf.readInt() : Integer.MAX_VALUE;
@@ -40,7 +41,7 @@ class IntegerArgumentPropertySerializer implements ArgumentPropertySerializer<In
   }
 
   @Override
-  public void serialize(IntegerArgumentType object, ByteBuf buf) {
+  public void serialize(IntegerArgumentType object, ByteBuf buf, ProtocolVersion protocolVersion) {
     boolean hasMinimum = object.getMinimum() != Integer.MIN_VALUE;
     boolean hasMaximum = object.getMaximum() != Integer.MAX_VALUE;
     byte flag = getFlags(hasMinimum, hasMaximum);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/LongArgumentPropertySerializer.java

@@ -22,6 +22,7 @@ import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumen
 import static com.velocitypowered.proxy.protocol.packet.brigadier.IntegerArgumentPropertySerializer.getFlags;
 
 import com.mojang.brigadier.arguments.LongArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 
 class LongArgumentPropertySerializer implements ArgumentPropertySerializer<LongArgumentType> {
@@ -33,7 +34,7 @@ class LongArgumentPropertySerializer implements ArgumentPropertySerializer<LongA
   }
 
   @Override
-  public LongArgumentType deserialize(ByteBuf buf) {
+  public LongArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     byte flags = buf.readByte();
     long minimum = (flags & HAS_MINIMUM) != 0 ? buf.readLong() : Long.MIN_VALUE;
     long maximum = (flags & HAS_MAXIMUM) != 0 ? buf.readLong() : Long.MAX_VALUE;
@@ -41,7 +42,7 @@ class LongArgumentPropertySerializer implements ArgumentPropertySerializer<LongA
   }
 
   @Override
-  public void serialize(LongArgumentType object, ByteBuf buf) {
+  public void serialize(LongArgumentType object, ByteBuf buf, ProtocolVersion protocolVersion) {
     boolean hasMinimum = object.getMinimum() != Long.MIN_VALUE;
     boolean hasMaximum = object.getMaximum() != Long.MAX_VALUE;
     byte flag = getFlags(hasMinimum, hasMaximum);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ModArgumentProperty.java

@@ -30,15 +30,15 @@ import java.util.concurrent.CompletableFuture;
 
 public class ModArgumentProperty implements ArgumentType<ByteBuf> {
 
-  private final String identifier;
+  private final ArgumentIdentifier identifier;
   private final ByteBuf data;
 
-  public ModArgumentProperty(String identifier, ByteBuf data) {
+  public ModArgumentProperty(ArgumentIdentifier identifier, ByteBuf data) {
     this.identifier = identifier;
     this.data = Unpooled.unreleasableBuffer(data.asReadOnly());
   }
 
-  public String getIdentifier() {
+  public ArgumentIdentifier getIdentifier() {
     return identifier;
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ModArgumentPropertySerializer.java

@@ -17,6 +17,7 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -30,14 +31,22 @@ class ModArgumentPropertySerializer implements ArgumentPropertySerializer<ModArg
   }
 
   @Override
-  public @Nullable ModArgumentProperty deserialize(ByteBuf buf) {
-    String identifier = ProtocolUtils.readString(buf);
+  public @Nullable ModArgumentProperty deserialize(ByteBuf buf, ProtocolVersion version) {
+    ArgumentIdentifier identifier;
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      int idx = ProtocolUtils.readVarInt(buf);
+      identifier = ArgumentIdentifier.id("crossstitch:identified_" + (idx < 0 ? "n" + (-idx) : idx),
+              ArgumentIdentifier.mapSet(version, idx));
+    } else {
+      identifier = ArgumentIdentifier.id(ProtocolUtils.readString(buf));
+    }
+
     byte[] extraData = ProtocolUtils.readByteArray(buf);
     return new ModArgumentProperty(identifier, Unpooled.wrappedBuffer(extraData));
   }
 
   @Override
-  public void serialize(ModArgumentProperty object, ByteBuf buf) {
+  public void serialize(ModArgumentProperty object, ByteBuf buf, ProtocolVersion version) {
     // This is special-cased by ArgumentPropertyRegistry
     throw new UnsupportedOperationException();
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/PassthroughProperty.java

@@ -23,18 +23,18 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 
 class PassthroughProperty<T> implements ArgumentType<T> {
 
-  private final String identifier;
+  private final ArgumentIdentifier identifier;
   private final ArgumentPropertySerializer<T> serializer;
   private final @Nullable T result;
 
-  PassthroughProperty(String identifier, ArgumentPropertySerializer<T> serializer,
+  PassthroughProperty(ArgumentIdentifier identifier, ArgumentPropertySerializer<T> serializer,
       @Nullable T result) {
     this.identifier = identifier;
     this.serializer = serializer;
     this.result = result;
   }
 
-  public String getIdentifier() {
+  public ArgumentIdentifier getIdentifier() {
     return identifier;
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/RegistryKeyArgumentSerializer.java

@@ -17,6 +17,7 @@
 
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 
 import io.netty.buffer.ByteBuf;
@@ -25,12 +26,12 @@ public class RegistryKeyArgumentSerializer implements ArgumentPropertySerializer
   static final RegistryKeyArgumentSerializer REGISTRY = new RegistryKeyArgumentSerializer();
 
   @Override
-  public RegistryKeyArgument deserialize(ByteBuf buf) {
+  public RegistryKeyArgument deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     return new RegistryKeyArgument(ProtocolUtils.readString(buf));
   }
 
   @Override
-  public void serialize(RegistryKeyArgument object, ByteBuf buf) {
+  public void serialize(RegistryKeyArgument object, ByteBuf buf, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeString(buf, object.getIdentifier());
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/StringArgumentPropertySerializer.java

@@ -18,6 +18,7 @@
 package com.velocitypowered.proxy.protocol.packet.brigadier;
 
 import com.mojang.brigadier.arguments.StringArgumentType;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
@@ -34,7 +35,7 @@ class StringArgumentPropertySerializer implements ArgumentPropertySerializer<Str
   }
 
   @Override
-  public StringArgumentType deserialize(ByteBuf buf) {
+  public StringArgumentType deserialize(ByteBuf buf, ProtocolVersion protocolVersion) {
     int type = ProtocolUtils.readVarInt(buf);
     switch (type) {
       case 0:
@@ -49,7 +50,7 @@ class StringArgumentPropertySerializer implements ArgumentPropertySerializer<Str
   }
 
   @Override
-  public void serialize(StringArgumentType object, ByteBuf buf) {
+  public void serialize(StringArgumentType object, ByteBuf buf, ProtocolVersion protocolVersion) {
     switch (object.getType()) {
       case SINGLE_WORD:
         ProtocolUtils.writeVarInt(buf, 0);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/ChatBuilder.java

@@ -0,0 +1,182 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.proxy.crypto.SignedChatCommand;
+import com.velocitypowered.proxy.crypto.SignedChatMessage;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import java.time.Instant;
+import java.util.UUID;
+import net.kyori.adventure.identity.Identity;
+import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ChatBuilder {
+
+  private final ProtocolVersion version;
+
+  private @MonotonicNonNull Component component;
+  private @MonotonicNonNull String message;
+  private @MonotonicNonNull SignedChatMessage signedChatMessage;
+  private @MonotonicNonNull SignedChatCommand signedCommand;
+
+  private @Nullable Player sender;
+  private @Nullable Identity senderIdentity;
+
+  private ChatType type = ChatType.CHAT;
+
+  private ChatBuilder(ProtocolVersion version) {
+    this.version = version;
+  }
+
+  public static ChatBuilder builder(ProtocolVersion version) {
+    return new ChatBuilder(Preconditions.checkNotNull(version));
+  }
+
+  public ChatBuilder component(Component message) {
+    this.component = Preconditions.checkNotNull(message);
+    return this;
+  }
+
+  /**
+   * Sets the message to the provided message.
+   *
+   * @param message The message for the chat.
+   * @return {@code this}
+   */
+  public ChatBuilder message(String message) {
+    Preconditions.checkArgument(this.message == null);
+    this.message = Preconditions.checkNotNull(message);
+    return this;
+  }
+
+  /**
+   * Sets the signed message to the provided message.
+   *
+   * @param message The signed message for the chat.
+   * @return {@code this}
+   */
+  public ChatBuilder message(SignedChatMessage message) {
+    Preconditions.checkNotNull(message);
+    Preconditions.checkArgument(this.message == null);
+    this.message = message.getMessage();
+    this.signedChatMessage = message;
+    return this;
+  }
+
+  /**
+   * Sets the signed command to the provided command.
+   *
+   * @param command The signed command for the chat.
+   * @return {@code this}
+   */
+  public ChatBuilder message(SignedChatCommand command) {
+    Preconditions.checkNotNull(command);
+    Preconditions.checkArgument(this.message == null);
+    this.message = command.getBaseCommand();
+    this.signedCommand = command;
+    return this;
+  }
+
+
+  public ChatBuilder setType(ChatType type) {
+    this.type = type;
+    return this;
+  }
+
+  public ChatBuilder asPlayer(@Nullable Player player) {
+    this.sender = player;
+    return this;
+  }
+
+  public ChatBuilder forIdentity(@Nullable Identity identity) {
+    this.senderIdentity = identity;
+    return this;
+  }
+
+  public ChatBuilder asServer() {
+    this.sender = null;
+    return this;
+  }
+
+  /**
+   * Creates a {@link MinecraftPacket} which can be sent to the client; using the provided information in the builder.
+   *
+   * @return The {@link MinecraftPacket} to send to the client.
+   */
+  public MinecraftPacket toClient() {
+    // This is temporary
+    UUID identity = sender == null ? (senderIdentity == null ? Identity.nil().uuid()
+        : senderIdentity.uuid()) : sender.getUniqueId();
+    Component msg = component == null ? Component.text(message) : component;
+
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      return new SystemChat(msg, type.getId());
+    } else {
+      return new LegacyChat(ProtocolUtils.getJsonChatSerializer(version).serialize(msg), type.getId(), identity);
+    }
+  }
+
+  /**
+   * Creates a {@link MinecraftPacket} which can be sent to the server; using the provided information in the builder.
+   *
+   * @return The {@link MinecraftPacket} to send to the server.
+   */
+  public MinecraftPacket toServer() {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_19) >= 0) {
+      if (signedChatMessage != null) {
+        return new PlayerChat(signedChatMessage);
+      } else if (signedCommand != null) {
+        return new PlayerCommand(signedCommand);
+      } else {
+        // Well crap
+        if (message.startsWith("/")) {
+          return new PlayerCommand(message.substring(1), ImmutableList.of(), Instant.now());
+        } else {
+          // This will produce an error on the server, but needs to be here.
+          return new PlayerChat(message);
+        }
+      }
+    }
+    LegacyChat chat = new LegacyChat();
+    chat.setMessage(message);
+    return chat;
+  }
+
+  public static enum ChatType {
+    CHAT((byte) 0),
+    SYSTEM((byte) 1),
+    GAME_INFO((byte) 2);
+
+    private final byte raw;
+
+    ChatType(byte raw) {
+      this.raw = raw;
+    }
+
+    public byte getId() {
+      return raw;
+    }
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/LegacyChat.java

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.protocol.packet;
+package com.velocitypowered.proxy.protocol.packet.chat;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
@@ -23,12 +23,11 @@ import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
+import java.util.UUID;
 import net.kyori.adventure.identity.Identity;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-import java.util.UUID;
-
-public class Chat implements MinecraftPacket {
+public class LegacyChat implements MinecraftPacket {
 
   public static final byte CHAT_TYPE = (byte) 0;
   public static final byte SYSTEM_TYPE = (byte) 1;
@@ -41,15 +40,21 @@ public class Chat implements MinecraftPacket {
   private byte type;
   private @Nullable UUID sender;
 
-  public Chat() {
+  public LegacyChat() {
   }
 
-  public Chat(String message, byte type, UUID sender) {
+  /**
+   * Creates a Chat packet.
+   */
+  public LegacyChat(String message, byte type, UUID sender) {
     this.message = message;
     this.type = type;
     this.sender = sender;
   }
 
+  /**
+   * Retrieves the Chat message.
+   */
   public String getMessage() {
     if (message == null) {
       throw new IllegalStateException("Message is not specified");
@@ -115,20 +120,4 @@ public class Chat implements MinecraftPacket {
   public boolean handle(MinecraftSessionHandler handler) {
     return handler.handle(this);
   }
-
-  public static Chat createClientbound(Identity identity,
-      net.kyori.adventure.text.Component component, ProtocolVersion version) {
-    return createClientbound(component, CHAT_TYPE, identity.uuid(), version);
-  }
-
-  public static Chat createClientbound(net.kyori.adventure.text.Component component, byte type,
-      UUID sender, ProtocolVersion version) {
-    Preconditions.checkNotNull(component, "component");
-    return new Chat(ProtocolUtils.getJsonChatSerializer(version).serialize(component), type,
-        sender);
-  }
-
-  public static Chat createServerbound(String message) {
-    return new Chat(message, CHAT_TYPE, EMPTY_SENDER);
-  }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/PlayerChat.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.google.common.primitives.Longs;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.crypto.EncryptionUtils;
+import com.velocitypowered.proxy.crypto.SignedChatMessage;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import io.netty.buffer.ByteBuf;
+import java.time.Instant;
+import java.util.UUID;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class PlayerChat implements MinecraftPacket {
+
+  private String message;
+  private boolean signedPreview;
+  private boolean unsigned = false;
+  private @Nullable Instant expiry;
+  private @Nullable byte[] signature;
+  private @Nullable byte[] salt;
+
+  public PlayerChat() {
+  }
+
+  public PlayerChat(String message) {
+    this.message = message;
+    this.unsigned = true;
+  }
+
+  /**
+   * Create new {@link PlayerChat} based on a previously {@link SignedChatMessage}.
+   *
+   * @param message The {@link SignedChatMessage} to turn into {@link PlayerChat}.
+   */
+  public PlayerChat(SignedChatMessage message) {
+    this.message = message.getMessage();
+    this.expiry = message.getExpiryTemporal();
+    this.salt = message.getSalt();
+    this.signature = message.getSignature();
+    this.signedPreview = message.isPreviewSigned();
+  }
+
+  public Instant getExpiry() {
+    return expiry;
+  }
+
+  public boolean isUnsigned() {
+    return unsigned;
+  }
+
+  public String getMessage() {
+    return message;
+  }
+
+  public boolean isSignedPreview() {
+    return signedPreview;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    message = ProtocolUtils.readString(buf, 256);
+
+    long expiresAt = buf.readLong();
+    long saltLong = buf.readLong();
+    byte[] signatureBytes = ProtocolUtils.readByteArray(buf);
+
+    if (saltLong != 0L && signatureBytes.length > 0) {
+      salt = Longs.toByteArray(saltLong);
+      signature = signatureBytes;
+      expiry = Instant.ofEpochMilli(expiresAt);
+    } else if (saltLong == 0L && signature.length == 0) {
+      unsigned = true;
+    } else {
+      throw EncryptionUtils.INVALID_SIGNATURE;
+    }
+
+    signedPreview = buf.readBoolean();
+    if (signedPreview && unsigned) {
+      throw EncryptionUtils.PREVIEW_SIGNATURE_MISSING;
+    }
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    ProtocolUtils.writeString(buf, message);
+
+    buf.writeLong(unsigned ? Instant.now().toEpochMilli() : expiry.toEpochMilli());
+    buf.writeLong(unsigned ? 0L : Longs.fromByteArray(salt));
+    ProtocolUtils.writeByteArray(buf, unsigned ? EncryptionUtils.EMPTY : signature);
+
+    buf.writeBoolean(signedPreview);
+  }
+
+  /**
+   * Validates a signature and creates a {@link SignedChatMessage} from the given signature.
+   *
+   * @param signer the signer's information
+   * @param sender the sender of the message
+   * @param mustSign instructs the function to throw if the signature is invalid.
+   * @return The {@link SignedChatMessage} or null if the signature couldn't be verified.
+   * @throws com.velocitypowered.proxy.util.except.QuietDecoderException when mustSign is {@code true} and the signature
+   *                                                                     is invalid.
+   */
+  public SignedChatMessage signedContainer(IdentifiedKey signer, UUID sender, boolean mustSign) {
+    if (unsigned) {
+      if (mustSign) {
+        throw EncryptionUtils.INVALID_SIGNATURE;
+      }
+      return null;
+    }
+
+    return new SignedChatMessage(message, signer.getSignedPublicKey(), sender, expiry, signature, salt, signedPreview);
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/PlayerChatPreview.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import io.netty.buffer.ByteBuf;
+
+public class PlayerChatPreview implements MinecraftPacket {
+
+  private int id;
+  private String query;
+
+  public int getId() {
+    return id;
+  }
+
+  public String getQuery() {
+    return query;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    id = buf.readInt();
+    query = ProtocolUtils.readString(buf, 256);
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    buf.writeInt(id);
+    ProtocolUtils.writeString(buf, query);
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/PlayerCommand.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.primitives.Longs;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.crypto.EncryptionUtils;
+import com.velocitypowered.proxy.crypto.SignedChatCommand;
+import com.velocitypowered.proxy.crypto.SignedChatMessage;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.util.except.QuietDecoderException;
+import io.netty.buffer.ByteBuf;
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+public class PlayerCommand implements MinecraftPacket {
+
+  private static final int MAX_NUM_ARGUMENTS = 8;
+  private static final int MAX_LENGTH_ARGUMENTS = 16;
+  private static final QuietDecoderException LIMITS_VIOLATION =
+      new QuietDecoderException("Command arguments incorrect size");
+
+  private boolean unsigned = false;
+  private String command;
+  private Instant timestamp;
+  private long salt;
+  private boolean signedPreview; // Good god. Please no.
+  private Map<String, byte[]> arguments = ImmutableMap.of();
+
+  public boolean isSignedPreview() {
+    return signedPreview;
+  }
+
+  public Instant getTimestamp() {
+    return timestamp;
+  }
+
+  public boolean isUnsigned() {
+    return unsigned;
+  }
+
+  public String getCommand() {
+    return command;
+  }
+
+  public PlayerCommand() {
+  }
+
+  /**
+   * Creates an {@link PlayerCommand} packet based on a command and list of arguments.
+   *
+   * @param command the command to run
+   * @param arguments the arguments of the command
+   * @param timestamp the timestamp of the command execution
+   */
+  public PlayerCommand(String command, List<String> arguments, Instant timestamp) {
+    this.unsigned = true;
+    ImmutableMap.Builder<String, byte[]> builder = ImmutableMap.builder();
+    arguments.forEach(entry -> builder.put(entry, EncryptionUtils.EMPTY));
+    this.arguments = builder.build();
+    this.timestamp = timestamp;
+    this.command = command;
+    this.signedPreview = false;
+    this.salt = 0L;
+  }
+
+  /**
+   * Create new {@link PlayerCommand} based on a previously {@link SignedChatCommand}.
+   *
+   * @param signedCommand The {@link SignedChatCommand} to turn into {@link PlayerCommand}.
+   */
+  public PlayerCommand(SignedChatCommand signedCommand) {
+    this.command = signedCommand.getBaseCommand();
+    this.arguments = ImmutableMap.copyOf(signedCommand.getSignatures());
+    this.timestamp = signedCommand.getExpiryTemporal();
+    this.salt = Longs.fromByteArray(signedCommand.getSalt());
+    this.signedPreview = signedCommand.isPreviewSigned();
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    command = ProtocolUtils.readString(buf, 256);
+    timestamp = Instant.ofEpochMilli(buf.readLong());
+
+    salt = buf.readLong();
+    if (salt == 0L) {
+      unsigned = true;
+    }
+
+    int mapSize = ProtocolUtils.readVarInt(buf);
+    if (mapSize > MAX_NUM_ARGUMENTS) {
+      throw LIMITS_VIOLATION;
+    }
+    // Mapped as Argument : signature
+    ImmutableMap.Builder<String, byte[]> entries = ImmutableMap.builderWithExpectedSize(mapSize);
+    for (int i = 0; i < mapSize; i++) {
+      entries.put(ProtocolUtils.readString(buf, MAX_LENGTH_ARGUMENTS),
+          ProtocolUtils.readByteArray(buf, unsigned ? 0 : ProtocolUtils.DEFAULT_MAX_STRING_SIZE));
+    }
+    arguments = entries.build();
+
+    signedPreview = buf.readBoolean();
+    if (unsigned && signedPreview) {
+      throw EncryptionUtils.PREVIEW_SIGNATURE_MISSING;
+    }
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    ProtocolUtils.writeString(buf, command);
+    buf.writeLong(timestamp.toEpochMilli());
+
+    buf.writeLong(unsigned ? 0L : salt);
+
+    int size = arguments.size();
+    if (size > MAX_NUM_ARGUMENTS) {
+      throw LIMITS_VIOLATION;
+    }
+    ProtocolUtils.writeVarInt(buf, size);
+    for (Map.Entry<String, byte[]> entry : arguments.entrySet()) {
+      // What annoys me is that this isn't "sorted"
+      ProtocolUtils.writeString(buf, entry.getKey());
+      ProtocolUtils.writeByteArray(buf, unsigned ? EncryptionUtils.EMPTY : entry.getValue());
+    }
+
+    buf.writeBoolean(signedPreview);
+
+  }
+
+  /**
+   * Validates a signature and creates a {@link SignedChatCommand} from the given signature.
+   *
+   * @param signer the signer's information
+   * @param sender the sender of the message
+   * @param mustSign instructs the function to throw if the signature is invalid.
+   * @return The {@link SignedChatCommand} or null if the signature couldn't be verified.
+   * @throws com.velocitypowered.proxy.util.except.QuietDecoderException when mustSign is {@code true} and the signature
+   *                                                                     is invalid.
+   */
+  public SignedChatCommand signedContainer(IdentifiedKey signer, UUID sender, boolean mustSign) {
+    if (unsigned) {
+      if (mustSign) {
+        throw EncryptionUtils.INVALID_SIGNATURE;
+      }
+      return null;
+    }
+
+    return new SignedChatCommand(command, signer.getSignedPublicKey(), sender, timestamp,
+        arguments, Longs.toByteArray(salt), signedPreview);
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/ServerChatPreview.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import io.netty.buffer.ByteBuf;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ServerChatPreview implements MinecraftPacket {
+
+  private int id;
+  private @Nullable Component preview;
+
+  public Component getPreview() {
+    return preview;
+  }
+
+  public int getId() {
+    return id;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    id = buf.readInt();
+    if (buf.readBoolean()) {
+      preview = GsonComponentSerializer.gson().deserialize(ProtocolUtils.readString(buf));
+    }
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    buf.writeInt(id);
+    if (preview != null) {
+      buf.writeBoolean(true);
+      ProtocolUtils.writeString(buf, GsonComponentSerializer.gson().serialize(preview));
+    } else {
+      buf.writeBoolean(false);
+    }
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/ServerPlayerChat.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import io.netty.buffer.ByteBuf;
+import java.time.Instant;
+import java.util.UUID;
+import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ServerPlayerChat implements MinecraftPacket {
+
+  private Component component;
+  private @Nullable Component unsignedComponent;
+  private int type;
+
+  private UUID sender;
+  private Component senderName;
+  private @Nullable Component teamName;
+
+  private Instant expiry;
+
+  public void setType(int type) {
+    this.type = type;
+  }
+
+  public void setComponent(Component component) {
+    this.component = component;
+  }
+
+  public int getType() {
+    return type;
+  }
+
+  public Component getComponent() {
+    return component;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    component = ProtocolUtils.getJsonChatSerializer(protocolVersion).deserialize(ProtocolUtils.readString(buf));
+    if (buf.readBoolean()) {
+      unsignedComponent = component = ProtocolUtils.getJsonChatSerializer(protocolVersion)
+          .deserialize(ProtocolUtils.readString(buf));
+    }
+
+    type = ProtocolUtils.readVarInt(buf);
+
+    sender = ProtocolUtils.readUuid(buf);
+    senderName = ProtocolUtils.getJsonChatSerializer(protocolVersion).deserialize(ProtocolUtils.readString(buf));
+    if (buf.readBoolean()) {
+      teamName = ProtocolUtils.getJsonChatSerializer(protocolVersion).deserialize(ProtocolUtils.readString(buf));
+    }
+
+    expiry = Instant.ofEpochMilli(buf.readLong());
+
+    long salt = buf.readLong();
+    byte[] signature = ProtocolUtils.readByteArray(buf);
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    // TBD
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/SystemChat.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import io.netty.buffer.ByteBuf;
+import net.kyori.adventure.text.Component;
+
+public class SystemChat implements MinecraftPacket {
+
+  public SystemChat() {}
+
+  public SystemChat(Component component, int type) {
+    this.component = component;
+    this.type = type;
+  }
+
+  private Component component;
+  private int type;
+
+  public int getType() {
+    return type;
+  }
+
+  public Component getComponent() {
+    return component;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    component = ProtocolUtils.getJsonChatSerializer(protocolVersion).deserialize(ProtocolUtils.readString(buf));
+    type = ProtocolUtils.readVarInt(buf);
+  }
+
+  @Override
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+    ProtocolUtils.writeString(buf, ProtocolUtils.getJsonChatSerializer(protocolVersion).serialize(component));
+    ProtocolUtils.writeVarInt(buf, type);
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabList.java

@@ -18,6 +18,7 @@
 package com.velocitypowered.proxy.tablist;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
@@ -119,10 +120,16 @@ public class VelocityTabList implements TabList {
     return Collections.unmodifiableCollection(this.entries.values());
   }
 
+  @Override
+  public TabListEntry buildEntry(GameProfile profile, @Nullable Component displayName, int latency, int gameMode) {
+    return buildEntry(profile, displayName, latency, gameMode, null);
+  }
+
   @Override
   public TabListEntry buildEntry(GameProfile profile,
-      net.kyori.adventure.text.@Nullable Component displayName, int latency, int gameMode) {
-    return new VelocityTabListEntry(this, profile, displayName, latency, gameMode);
+                                 net.kyori.adventure.text.@Nullable Component displayName,
+                                 int latency, int gameMode, @Nullable IdentifiedKey key) {
+    return new VelocityTabListEntry(this, profile, displayName, latency, gameMode, key);
   }
 
   /**

proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabListEntry.java

@@ -17,6 +17,7 @@
 
 package com.velocitypowered.proxy.tablist;
 
+import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
@@ -31,14 +32,17 @@ public class VelocityTabListEntry implements TabListEntry {
   private net.kyori.adventure.text.Component displayName;
   private int latency;
   private int gameMode;
+  private @Nullable IdentifiedKey playerKey;
 
   VelocityTabListEntry(VelocityTabList tabList, GameProfile profile,
-      net.kyori.adventure.text.@Nullable Component displayName, int latency, int gameMode) {
+      net.kyori.adventure.text.@Nullable Component displayName, int latency, int gameMode,
+                       @Nullable IdentifiedKey playerKey) {
     this.tabList = tabList;
     this.profile = profile;
     this.displayName = displayName;
     this.latency = latency;
     this.gameMode = gameMode;
+    this.playerKey = playerKey;
   }
 
   @Override
@@ -98,4 +102,13 @@ public class VelocityTabListEntry implements TabListEntry {
   void setGameModeInternal(int gameMode) {
     this.gameMode = gameMode;
   }
+
+  @Override
+  public IdentifiedKey getIdentifiedKey() {
+    return playerKey;
+  }
+
+  void setPlayerKeyInternal(IdentifiedKey playerKey) {
+    this.playerKey = playerKey;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabListEntryLegacy.java

@@ -26,7 +26,7 @@ public class VelocityTabListEntryLegacy extends VelocityTabListEntry {
 
   VelocityTabListEntryLegacy(VelocityTabListLegacy tabList, GameProfile profile,
       @Nullable Component displayName, int latency, int gameMode) {
-    super(tabList, profile, displayName, latency, gameMode);
+    super(tabList, profile, displayName, latency, gameMode, null);
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/util/EncryptionUtils.java

@@ -1,89 +0,0 @@
-/*
- * Copyright (C) 2018 Velocity Contributors
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package com.velocitypowered.proxy.util;
-
-import java.math.BigInteger;
-import java.security.GeneralSecurityException;
-import java.security.KeyPair;
-import java.security.KeyPairGenerator;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.security.PublicKey;
-import javax.crypto.Cipher;
-
-public enum EncryptionUtils {
-  ;
-
-  /**
-   * Generates an RSA key pair.
-   *
-   * @param keysize the key size (in bits) for the RSA key pair
-   * @return the generated key pair
-   */
-  public static KeyPair createRsaKeyPair(final int keysize) {
-    try {
-      final KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
-      generator.initialize(keysize);
-      return generator.generateKeyPair();
-    } catch (final NoSuchAlgorithmException e) {
-      throw new RuntimeException("Unable to generate RSA keypair", e);
-    }
-  }
-
-  /**
-   * Generates a hex digest in two's complement form for use with the Mojang joinedServer endpoint.
-   *
-   * @param digest the bytes to digest
-   * @return the hex digest
-   */
-  public static String twosComplementHexdigest(byte[] digest) {
-    return new BigInteger(digest).toString(16);
-  }
-
-  /**
-   * Decrypts an RSA message.
-   *
-   * @param keyPair the key pair to use
-   * @param bytes the bytes of the encrypted message
-   * @return the decrypted message
-   * @throws GeneralSecurityException if the message couldn't be decoded
-   */
-  public static byte[] decryptRsa(KeyPair keyPair, byte[] bytes) throws GeneralSecurityException {
-    Cipher cipher = Cipher.getInstance("RSA");
-    cipher.init(Cipher.DECRYPT_MODE, keyPair.getPrivate());
-    return cipher.doFinal(bytes);
-  }
-
-  /**
-   * Generates the server ID for the hasJoined endpoint.
-   *
-   * @param sharedSecret the shared secret between the client and the proxy
-   * @param key the RSA public key
-   * @return the server ID
-   */
-  public static String generateServerId(byte[] sharedSecret, PublicKey key) {
-    try {
-      MessageDigest digest = MessageDigest.getInstance("SHA-1");
-      digest.update(sharedSecret);
-      digest.update(key.getEncoded());
-      return twosComplementHexdigest(digest.digest());
-    } catch (NoSuchAlgorithmException e) {
-      throw new AssertionError(e);
-    }
-  }
-}

proxy/src/main/resources/com/velocitypowered/proxy/l10n/messages.properties

@@ -29,7 +29,7 @@ velocity.error.modern-forwarding-needs-new-client=This server is only compatible
 velocity.error.modern-forwarding-failed=Your server did not send a forwarding request to the proxy. Make sure the server is configured for Velocity forwarding.
 velocity.error.moved-to-new-server=You were kicked from {0}: {1}
 velocity.error.no-available-servers=There are no available servers to connect you to. Try again later or contact an admin.
-velocity.error.illegal-chat-characters=Illegal characters in chat
+velocity.error.illegal-legacyChat-characters=Illegal characters in legacyChat
 
 # Commands
 velocity.command.generic-error=An error occurred while running this command.

proxy/src/main/resources/default-velocity.toml

@@ -15,6 +15,9 @@ show-max-players = 500
 # Should we authenticate players with Mojang? By default, this is on.
 online-mode = true
 
+# Should the proxy enforce the new public key security standard? By default, this is on.
+force-key-authentication = true
+
 # If client's ISP/AS sent from this proxy is different from the one from Mojang's
 # authentication server, the player is kicked. This disallows some VPN and proxy
 # connections but is a weak form of protection.

proxy/src/test/java/com/velocitypowered/proxy/util/EncryptionUtilsTest.java

@@ -19,8 +19,10 @@ package com.velocitypowered.proxy.util;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import com.velocitypowered.proxy.crypto.EncryptionUtils;
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
+
 import org.junit.jupiter.api.Test;
 
 class EncryptionUtilsTest {