Revert "Volatile encryption (#515)" (#516)

This reverts commit 0f15d4a273.

src/main/java/net/minestom/server/network/packet/client/login/EncryptionResponsePacket.java

@@ -22,7 +22,6 @@ import java.net.http.HttpClient;
 import java.net.http.HttpRequest;
 import java.net.http.HttpResponse;
 import java.nio.charset.StandardCharsets;
-import java.security.KeyPair;
 import java.util.Arrays;
 import java.util.UUID;
 
@@ -51,9 +50,8 @@ public class EncryptionResponsePacket implements ClientPreplayPacket {
                 MinecraftServer.LOGGER.error("{} tried to login with an invalid nonce!", loginUsername);
                 return;
             }
-            final KeyPair keyPair = MojangAuth.getKeyPair();
+
-            final SecretKey secretKey = MojangCrypt.decryptByteToSecretKey(keyPair.getPrivate(), sharedSecret);
+            final byte[] digestedData = MojangCrypt.digestData("", MojangAuth.getKeyPair().getPublic(), getSecretKey());
-            final byte[] digestedData = MojangCrypt.digestData("", keyPair.getPublic(), secretKey);
             if (digestedData == null) {
                 // Incorrect key, probably because of the client
                 MinecraftServer.LOGGER.error("Connection {} failed initializing encryption.", socketConnection.getRemoteAddress());
@@ -80,7 +78,7 @@ public class EncryptionResponsePacket implements ClientPreplayPacket {
                         // Invalid response
                         return;
                     }
-                    socketConnection.setEncryptionKey(secretKey);
+                    socketConnection.setEncryptionKey(getSecretKey());
                     UUID profileUUID = UUID.fromString(gameProfile.get("id").getAsString()
                             .replaceFirst("(\\w{8})(\\w{4})(\\w{4})(\\w{4})(\\w{12})", "$1-$2-$3-$4-$5"));
                     final String profileName = gameProfile.get("name").getAsString();
@@ -106,6 +104,10 @@ public class EncryptionResponsePacket implements ClientPreplayPacket {
         ByteArrayData.encodeByteArray(writer, verifyToken);
     }
 
+    private SecretKey getSecretKey() {
+        return MojangCrypt.decryptByteToSecretKey(MojangAuth.getKeyPair().getPrivate(), sharedSecret);
+    }
+
     private byte[] getNonce() {
         return MojangAuth.getKeyPair().getPrivate() == null ?
                 this.verifyToken : MojangCrypt.decryptUsingKey(MojangAuth.getKeyPair().getPrivate(), this.verifyToken);

src/main/java/net/minestom/server/network/packet/client/login/LoginStartPacket.java

@@ -69,7 +69,8 @@ public class LoginStartPacket implements ClientPreplayPacket {
             }
             final PlayerSocketConnection socketConnection = (PlayerSocketConnection) connection;
             socketConnection.setConnectionState(ConnectionState.LOGIN);
-            socketConnection.sendPacket(new EncryptionRequestPacket(socketConnection));
+            EncryptionRequestPacket encryptionRequestPacket = new EncryptionRequestPacket(socketConnection);
+            socketConnection.sendPacket(encryptionRequestPacket);
         } else {
             final boolean bungee = BungeeCordProxy.isEnabled();
             // Offline

src/main/java/net/minestom/server/network/player/PlayerSocketConnection.java

@@ -36,7 +36,6 @@ import java.nio.channels.SocketChannel;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
@@ -48,18 +47,18 @@ import java.util.zip.Inflater;
 @ApiStatus.Internal
 public class PlayerSocketConnection extends PlayerConnection {
     private final static Logger LOGGER = LoggerFactory.getLogger(PlayerSocketConnection.class);
-    private static final AtomicReferenceFieldUpdater<PlayerSocketConnection, EncryptionInfo> ENCRYPTION_UPDATER =
-            AtomicReferenceFieldUpdater.newUpdater(PlayerSocketConnection.class, EncryptionInfo.class, "encryptionInfo");
 
     private final Worker worker;
     private final SocketChannel channel;
     private SocketAddress remoteAddress;
 
-    private volatile EncryptionInfo encryptionInfo;
+    private boolean encrypted = false;
     private boolean compressed = false;
 
     //Could be null. Only used for Mojang Auth
     private byte[] nonce = new byte[4];
+    private Cipher decryptCipher;
+    private Cipher encryptCipher;
 
     // Data from client packets
     private String loginUsername;
@@ -93,11 +92,11 @@ public class PlayerSocketConnection extends PlayerConnection {
     public void processPackets(Worker.Context workerContext, PacketProcessor packetProcessor) {
         final BinaryBuffer readBuffer = workerContext.readBuffer;
         // Decrypt data
-        EncryptionInfo encryptionInfo = this.encryptionInfo;
+        if (encrypted) {
-        if (encryptionInfo != null) {
+            final Cipher cipher = decryptCipher;
             ByteBuffer input = readBuffer.asByteBuffer(0, readBuffer.writerOffset());
             try {
-                encryptionInfo.decryptCipher().update(input, input.duplicate());
+                cipher.update(input, input.duplicate());
             } catch (ShortBufferException e) {
                 MinecraftServer.getExceptionManager().handleException(e);
                 return;
@@ -176,10 +175,12 @@ public class PlayerSocketConnection extends PlayerConnection {
      * @throws IllegalStateException if encryption is already enabled for this connection
      */
     public void setEncryptionKey(@NotNull SecretKey secretKey) {
-        final EncryptionInfo prev = ENCRYPTION_UPDATER.getAndSet(this,
+        Check.stateCondition(encrypted, "Encryption is already enabled!");
-                new EncryptionInfo(MojangCrypt.getCipher(2, secretKey), MojangCrypt.getCipher(1, secretKey)));
+        synchronized (bufferLock) {
-        if (prev != null)
+            this.decryptCipher = MojangCrypt.getCipher(2, secretKey);
-            throw new IllegalStateException("Encryption was already enabled for this connection");
+            this.encryptCipher = MojangCrypt.getCipher(1, secretKey);
+            this.encrypted = true;
+        }
     }
 
     /**
@@ -230,20 +231,19 @@ public class PlayerSocketConnection extends PlayerConnection {
 
     @ApiStatus.Internal
     public void write(@NotNull ByteBuffer buffer, int index, int length) {
-        EncryptionInfo encryptionInfo = this.encryptionInfo;
-        if (encryptionInfo != null) {
-            ByteBuffer output = PacketUtils.localBuffer();
-            try {
-                encryptionInfo.encryptCipher().update(buffer.slice(index, length), output);
-                buffer = output.flip();
-                index = 0;
-            } catch (ShortBufferException e) {
-                MinecraftServer.getExceptionManager().handleException(e);
-                return;
-            }
-        }
-
         synchronized (bufferLock) {
+            if (encrypted) { // Encryption support
+                ByteBuffer output = PacketUtils.localBuffer();
+                try {
+                    this.encryptCipher.update(buffer.slice(index,length), output);
+                    buffer = output.flip();
+                    index = 0;
+                } catch (ShortBufferException e) {
+                    MinecraftServer.getExceptionManager().handleException(e);
+                    return;
+                }
+            }
+
             BinaryBuffer localBuffer = tickBuffer.getPlain();
             final int capacity = localBuffer.capacity();
             if (length <= capacity) {
@@ -472,7 +472,4 @@ public class PlayerSocketConnection extends PlayerConnection {
     public void setNonce(byte[] nonce) {
         this.nonce = nonce;
     }
-
-    public record EncryptionInfo(Cipher decryptCipher, Cipher encryptCipher) {
-    }
 }