Test

build.gradle

@@ -12,9 +12,18 @@ repositories {
     // Loom adds the essential maven repositories to download Minecraft and libraries from automatically.
     // See https://docs.gradle.org/current/userguide/declaring_repositories.html
     // for more information about repositories.
+    maven {
+        name 'Xander Maven'
+        url 'https://maven.isxander.dev/releases'
+    }
+    maven {
+        name 'TerraformersMC'
+        url 'https://maven.terraformersmc.com/releases'
+    }
 }
 
 dependencies {
+    implementation group: 'com.google.code.gson', name: 'gson', version: '2.10.1'
     // To change the versions see the gradle.properties file
     minecraft "com.mojang:minecraft:${project.minecraft_version}"
     mappings "net.fabricmc:yarn:${project.yarn_mappings}:v2"
@@ -22,6 +31,8 @@ dependencies {
 
     // Fabric API. This is technically optional, but you probably want it anyway.
     modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"
+    modImplementation "dev.isxander.yacl:yet-another-config-lib-fabric:${project.yacl_version}"
+    modImplementation "com.terraformersmc:modmenu:${project.modmenu_version}"
 }
 
 processResources {

gradle.properties

@@ -15,3 +15,5 @@ org.gradle.jvmargs=-Xmx1G
 # Dependencies
 	# check this on https://modmuss50.me/fabric.html
 	fabric_version=0.96.11+1.20.4
+	yacl_version=3.3.2+1.20.4
+	modmenu_version=9.1.0-beta.1

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

@@ -0,0 +1,24 @@
+package systems.brn.chatencryptor;
+
+public class ChatCoder {
+    // Encode byte array to BMP characters
+    public static String encodeToBmp(byte[] byteArray) {
+        StringBuilder bmpText = new StringBuilder();
+        for (int i = 0; i < byteArray.length; i += 2) {
+            char bmpChar = (char) ((byteArray[i] & 0xFF) << 8 | (byteArray[i + 1] & 0xFF));
+            bmpText.append(bmpChar);
+        }
+        return bmpText.toString();
+    }
+
+    // Decode BMP characters to byte array
+    public static byte[] decodeFromBmp(String bmpString) {
+        byte[] byteArray = new byte[bmpString.length() * 2];
+        for (int i = 0; i < bmpString.length(); i++) {
+            char bmpChar = bmpString.charAt(i);
+            byteArray[i * 2] = (byte) ((bmpChar >> 8) & 0xFF);
+            byteArray[i * 2 + 1] = (byte) (bmpChar & 0xFF);
+        }
+        return byteArray;
+    }
+}

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

@@ -0,0 +1,134 @@
+package systems.brn.chatencryptor;
+
+import com.google.gson.GsonBuilder;
+import dev.isxander.yacl3.api.*;
+import dev.isxander.yacl3.api.controller.StringControllerBuilder;
+import dev.isxander.yacl3.api.controller.TickBoxControllerBuilder;
+import dev.isxander.yacl3.config.v2.api.ConfigClassHandler;
+import dev.isxander.yacl3.config.v2.api.SerialEntry;
+import dev.isxander.yacl3.config.v2.api.serializer.GsonConfigSerializerBuilder;
+import net.fabricmc.loader.api.FabricLoader;
+import net.minecraft.client.gui.screen.Screen;
+import net.minecraft.text.Text;
+import net.minecraft.util.Identifier;
+
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.PKCS8EncodedKeySpec;
+import java.util.Base64;
+
+public class Config {
+    public static ConfigClassHandler<Config> HANDLER = ConfigClassHandler.createBuilder(Config.class)
+            .id(new Identifier("securechat", "securechat_config"))
+            .serializer(config -> GsonConfigSerializerBuilder.create(config)
+                    .setPath(FabricLoader.getInstance().getConfigDir().resolve("securechat.json"))
+                    .appendGsonBuilder(GsonBuilder::setPrettyPrinting) // not needed, pretty print by default
+                    .build())
+            .build();
+
+    @SerialEntry
+    public boolean enabled = false;
+    @SerialEntry
+    public String SecretKey = "";
+
+    @SerialEntry
+    public String Iv = "";
+    public IvParameterSpec getRawIv() {
+        byte[] byteIv = Base64.getDecoder().decode(HANDLER.instance().Iv);
+        return new IvParameterSpec(byteIv);
+    }
+
+    public SecretKey getRawKey() {
+        byte[] binary_key = Base64.getDecoder().decode(HANDLER.instance().SecretKey);
+        // Convert byte array back to SecretKey
+        return new SecretKeySpec(binary_key, 0, binary_key.length, "AES");
+    }
+
+    public Boolean isEnabled() {
+        return HANDLER.instance().enabled;
+    }
+
+    private static IvParameterSpec generateIv() {
+        byte[] iv = new byte[16];
+        new SecureRandom().nextBytes(iv);
+        return new IvParameterSpec(iv);
+    }
+
+    private String getDefaultIv() {
+        IvParameterSpec generatedIv = generateIv();
+        byte [] bytesIv = generatedIv.getIV();
+        return Base64.getEncoder().encodeToString(bytesIv);
+    }
+
+    private SecretKey generateKey() {
+        KeyGenerator kg;
+        try {
+            kg = KeyGenerator.getInstance("AES");
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+        kg.init(256);
+        return kg.generateKey();
+    }
+
+    private String getDefaultKey() {
+        SecretKey generatedKey = generateKey();
+        byte[] encodedKey = generatedKey.getEncoded();
+        return Base64.getEncoder().encodeToString(encodedKey);
+    }
+
+    private void setEnabled(Boolean newEnabled){
+
+        HANDLER.instance().enabled = newEnabled;
+        HANDLER.save();
+    }
+    private void setIv(String newIv){
+
+        HANDLER.instance().Iv = newIv;
+        HANDLER.save();
+    }
+    private void setSecretKey(String newSecretKey){
+
+        HANDLER.instance().SecretKey = newSecretKey;
+        HANDLER.save();
+    }
+
+    public Screen makeConfig(Screen parentScreen) {
+        HANDLER.load();
+        return YetAnotherConfigLib.createBuilder()
+                .title(Text.literal("SecureChat Config."))
+                .category(ConfigCategory.createBuilder()
+                        .name(Text.literal("General"))
+                        .tooltip(Text.literal("Here you can set some generic settings."))
+                        .group(OptionGroup.createBuilder()
+                                .name(Text.literal("General"))
+                                .description(OptionDescription.of(Text.literal("Here you can set some generic settings.")))
+                                .option(Option.<Boolean>createBuilder()
+                                        .name(Text.literal("Enabled"))
+                                        .description(OptionDescription.of(Text.literal("This will enable the encryption.")))
+                                        .binding(false, () -> HANDLER.instance().enabled, this::setEnabled)
+                                        .controller(TickBoxControllerBuilder::create)
+                                        .build())
+                                .option(Option.<String>createBuilder()
+                                        .name(Text.literal("Secret key"))
+                                        .description(OptionDescription.of(Text.literal("This be the key that will be used.")))
+                                        .binding(getDefaultKey(), () -> HANDLER.instance().Iv, this::setIv)
+                                        .controller(StringControllerBuilder::create)
+                                        .build())
+                                .option(Option.<String>createBuilder()
+                                        .name(Text.literal("Initialization vector"))
+                                        .description(OptionDescription.of(Text.literal("This be the initialization vector that will be used.")))
+                                        .binding(getDefaultIv(), () -> HANDLER.instance().SecretKey, this::setSecretKey)
+                                        .controller(StringControllerBuilder::create)
+                                        .build())
+                                .build())
+                        .build())
+                .build().generateScreen(parentScreen);
+    }
+}

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

@@ -0,0 +1,15 @@
+package systems.brn.chatencryptor;
+
+import com.terraformersmc.modmenu.api.ConfigScreenFactory;
+import com.terraformersmc.modmenu.api.ModMenuApi;
+
+public class ModMenuIntegration implements ModMenuApi {
+    @Override
+    public ConfigScreenFactory<?> getModConfigScreenFactory() {
+        return parent -> {
+            Config config = new Config();
+            Config.HANDLER.load();
+            return config.makeConfig(parent);
+        };
+    }
+}

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

@@ -17,46 +17,33 @@ import javax.crypto.Cipher;
 import javax.crypto.IllegalBlockSizeException;
 import javax.crypto.NoSuchPaddingException;
 import java.nio.charset.StandardCharsets;
-import java.security.*;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
 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 {
+                Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+                cipher.init(Cipher.ENCRYPT_MODE, Config.HANDLER.instance().getRawKey(), Config.HANDLER.instance().getRawIv());
                 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);
+                byte[] decodedMessage = ChatCoder.decodeFromBmp(strippedMessage);
+                Cipher decryptingCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+                decryptingCipher.update(decodedMessage);
                 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 |
+            catch (IllegalBlockSizeException | BadPaddingException | NoSuchAlgorithmException | NoSuchPaddingException | InvalidAlgorithmParameterException |
                    InvalidKeyException e){
                 return true;
             }
@@ -65,25 +52,29 @@ public class SecureChat implements ClientModInitializer {
     }
 
     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);
+        if(Config.HANDLER.instance().isEnabled()){
+            String encodedMessage;
+            try {
+                Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+                cipher.init(Cipher.DECRYPT_MODE, Config.HANDLER.instance().getRawKey(), Config.HANDLER.instance().getRawIv());
+                cipher.update(message.getBytes(StandardCharsets.UTF_8));
+                byte[] encryptedMessage = cipher.doFinal();
+                encodedMessage = ChatCoder.encodeToBmp(encryptedMessage);
+            } catch (IllegalBlockSizeException | BadPaddingException | InvalidKeyException | NoSuchPaddingException | InvalidAlgorithmParameterException |
+                     NoSuchAlgorithmException e) {
+                return message;
+            }
+            return '®' + encodedMessage + '®';
+        }
+        else {
+            return message;
         }
-        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

@@ -17,11 +17,15 @@
   "entrypoints": {
     "client": [
       "systems.brn.chatencryptor.SecureChat"
+    ],
+    "modmenu": [
+      "systems.brn.chatencryptor.ModMenuIntegration"
     ]
   },
   "depends": {
     "fabricloader": ">=${loader_version}",
     "fabric": "*",
-    "minecraft": "${minecraft_version}"
+    "minecraft": "${minecraft_version}",
+    "yet_another_config_lib_v3": "*"
   }
 }