The encoding is broken now

src/main/java/systems/brn/chatencryptor/ChatDecryptorClient.java

@@ -1,31 +0,0 @@
-package systems.brn.chatencryptor;
-
-import net.fabricmc.api.ClientModInitializer;
-import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientLifecycleEvents;
-import net.fabricmc.fabric.api.client.message.v1.ClientReceiveMessageEvents;
-import net.minecraft.client.MinecraftClient;
-import net.minecraft.text.Text;
-import net.minecraft.text.TranslatableTextContent;
-import java.util.Base64;
-
-public class ChatDecryptorClient implements ClientModInitializer {
-    @Override
-    public void onInitializeClient() {
-        ClientLifecycleEvents.CLIENT_STARTED.register(client -> {
-            // Register event listener for ClientTickEvents.END_CLIENT_TICK
-            ClientReceiveMessageEvents.ALLOW_CHAT.register((message, signedMessage, sender, params, receptionTimestamp) -> {
-                TranslatableTextContent content = (TranslatableTextContent) message.getContent();
-                String message_content = content.getArg(1).getString();
-                if(message_content.startsWith("BRNCrypt:")){
-                    String strippedMessage = message_content.replace("BRNCrypt:", "");
-                    String decodedMessage = new String(Base64.getDecoder().decode(strippedMessage));
-                    assert sender != null;
-                    String outputMessage = "Decoded from " + sender.getName() + ":" + decodedMessage;
-                    MinecraftClient.getInstance().inGameHud.getChatHud().addMessage(Text.of(outputMessage));
-                    return false;
-                }
-                return true;
-            });
-        });
-    }
-}

src/main/java/systems/brn/chatencryptor/ChatEncryptorClient.java

@@ -1,21 +0,0 @@
-package systems.brn.chatencryptor;
-
-import net.fabricmc.api.ClientModInitializer;
-import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientLifecycleEvents;
-import net.fabricmc.fabric.api.client.message.v1.ClientSendMessageEvents;
-
-import java.nio.charset.StandardCharsets;
-import java.util.Base64;
-
-public class ChatEncryptorClient implements ClientModInitializer {
-    @Override
-    public void onInitializeClient() {
-        ClientLifecycleEvents.CLIENT_STARTED.register(client -> {
-            // Register event listener for ClientTickEvents.END_CLIENT_TICK
-            ClientSendMessageEvents.MODIFY_CHAT.register(message -> {
-                String encodedMessage = Base64.getEncoder().withoutPadding().encodeToString(message.getBytes(StandardCharsets.UTF_8));
-                return "BRNCrypt:" + encodedMessage;
-            });
-        });
-    }
-}

src/main/java/systems/brn/chatencryptor/SecureChat.java

@@ -0,0 +1,91 @@
+package systems.brn.chatencryptor;
+
+import com.mojang.authlib.GameProfile;
+import net.fabricmc.api.ClientModInitializer;
+import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientLifecycleEvents;
+import net.fabricmc.fabric.api.client.message.v1.ClientReceiveMessageEvents;
+import net.fabricmc.fabric.api.client.message.v1.ClientSendMessageEvents;
+import net.minecraft.client.MinecraftClient;
+import net.minecraft.network.message.MessageType;
+import net.minecraft.network.message.SignedMessage;
+import net.minecraft.text.Text;
+import net.minecraft.text.TranslatableTextContent;
+import org.jetbrains.annotations.Nullable;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import java.nio.charset.StandardCharsets;
+import java.security.*;
+import java.time.Instant;
+import java.util.Arrays;
+
+public class SecureChat implements ClientModInitializer {
+
+    private PublicKey publicKey;
+    private PrivateKey privateKey;
+
+    private void initKeys() {
+        KeyPairGenerator kpg;
+        try {
+            kpg = KeyPairGenerator.getInstance("RSA");
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+        kpg.initialize(512);
+        KeyPair kp = kpg.genKeyPair();
+        publicKey = kp.getPublic();
+        privateKey = kp.getPrivate();
+    }
+
+    private boolean decryptChatMessage(Text message, @Nullable SignedMessage signedMessage, @Nullable GameProfile sender, MessageType.Parameters params, Instant receptionTimestamp) {
+        TranslatableTextContent content = (TranslatableTextContent) message.getContent();
+        String message_content = content.getArg(1).getString();
+        String player_name = content.getArg(0).getString();
+        if(message_content.startsWith("®") && message_content.endsWith("®")){
+            try {
+                String strippedMessage = message_content.replace("®", "");
+                byte[] decodedMessage = strippedMessage.getBytes(java.nio.charset.StandardCharsets.UTF_16);
+                byte[] unpaddedMessage = Arrays.copyOfRange(decodedMessage, 2, decodedMessage.length);
+                Cipher decryptingCipher = Cipher.getInstance("RSA");
+                decryptingCipher.init(Cipher.DECRYPT_MODE, privateKey);
+                decryptingCipher.update(unpaddedMessage);
+                String decryptedMessage = new String(decryptingCipher.doFinal());
+                String outputMessage = "{" + player_name + "} " + decryptedMessage;
+                MinecraftClient.getInstance().inGameHud.getChatHud().addMessage(Text.of(outputMessage));
+                return false;
+            }
+            catch (IllegalBlockSizeException | BadPaddingException | NoSuchAlgorithmException | NoSuchPaddingException |
+                   InvalidKeyException e){
+                return true;
+            }
+        }
+        return true;
+    }
+
+    private String encryptChatMessage(String message) {
+        String encodedMessage;
+        try {
+            Cipher encryptingCipher = Cipher.getInstance("RSA");
+            encryptingCipher.init(Cipher.ENCRYPT_MODE, publicKey);
+            encryptingCipher.update(message.getBytes(StandardCharsets.UTF_8));
+            byte[] encryptedMessage = encryptingCipher.doFinal();
+            encodedMessage = new String(encryptedMessage, java.nio.charset.StandardCharsets.UTF_16);
+        } catch (IllegalBlockSizeException | BadPaddingException | InvalidKeyException | NoSuchPaddingException |
+                 NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+        return '®' + encodedMessage + '®';
+    }
+
+    @Override
+    public void onInitializeClient() {
+        ClientLifecycleEvents.CLIENT_STARTED.register(client -> {
+            // Register event listener for ClientTickEvents.END_CLIENT_TICK
+            initKeys();
+            ClientReceiveMessageEvents.ALLOW_CHAT.register(this::decryptChatMessage);
+            ClientSendMessageEvents.MODIFY_CHAT.register(this::encryptChatMessage);
+        });
+    }
+}

src/main/resources/fabric.mod.json

@@ -16,8 +16,7 @@
   "environment": "client",
   "entrypoints": {
     "client": [
-      "systems.brn.chatencryptor.ChatEncryptorClient",
+      "systems.brn.chatencryptor.SecureChat"
-      "systems.brn.chatencryptor.ChatDecryptorClient"
     ]
   },
   "depends": {