Add key and IV length validation for AES operations, extract common cipher logic

Author: Ale32bit

common/src/main/java/me/alexdevs/classicPeripherals/core/Crypto.java

@@ -2,7 +2,6 @@
 
 import org.bouncycastle.crypto.Digest;
 import org.bouncycastle.crypto.InvalidCipherTextException;
-import org.bouncycastle.crypto.digests.*;
 import org.bouncycastle.crypto.engines.AESEngine;
 import org.bouncycastle.crypto.digests.MD5Digest;
 import org.bouncycastle.crypto.digests.SHA1Digest;
@@ -14,6 +13,7 @@
 import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
 import org.bouncycastle.crypto.params.*;
 import org.bouncycastle.crypto.signers.Ed25519Signer;
+import org.jspecify.annotations.NonNull;
 
 import javax.crypto.BadPaddingException;
 import java.nio.charset.Charset;
@@ -33,10 +33,6 @@ public static String toStr(byte[] bytes, boolean hex) {
         return new String(bytes, CHARSET);
     }
 
-    public static String toStr(byte[] bytes) {
-        return toStr(bytes, true);
-    }
-
     private static String digest(Digest digest, String data, boolean hex) {
         digest.update(data.getBytes(CHARSET), 0, data.length());
         byte[] hash = new byte[digest.getDigestSize()];
@@ -217,28 +213,25 @@ public static String encryptAes(String data, String key, String iv) throws BadPa
         var ivBytes = iv.getBytes(CHARSET);
         var dataBytes = data.getBytes(CHARSET);
 
-        var cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESEngine()), new PKCS7Padding());
+        var cipher = new PaddedBufferedBlockCipher(CBCBlockCipher.newInstance(AESEngine.newInstance()), new PKCS7Padding());
         cipher.init(true, new ParametersWithIV(new KeyParameter(keyBytes), ivBytes));
 
-        var output = new byte[cipher.getOutputSize(dataBytes.length)];
-        int len = cipher.processBytes(dataBytes, 0, dataBytes.length, output, 0);
-        try {
-            len += cipher.doFinal(output, len);
-        } catch (InvalidCipherTextException e) {
-            throw new BadPaddingException(e.getMessage());
-        }
-
-        return new String(output, 0, len, CHARSET);
+        return getString(dataBytes, cipher);
     }
 
     public static String decryptAes(String data, String key, String iv) throws BadPaddingException {
         var keyBytes = key.getBytes(CHARSET);
         var ivBytes = iv.getBytes(CHARSET);
         var dataBytes = data.getBytes(CHARSET);
 
-        var cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESEngine()), new PKCS7Padding());
+        var cipher = new PaddedBufferedBlockCipher(CBCBlockCipher.newInstance(AESEngine.newInstance()), new PKCS7Padding());
         cipher.init(false, new ParametersWithIV(new KeyParameter(keyBytes), ivBytes));
 
+        return getString(dataBytes, cipher);
+    }
+
+    @NonNull
+    private static String getString(byte[] dataBytes, PaddedBufferedBlockCipher cipher) throws BadPaddingException {
         var output = new byte[cipher.getOutputSize(dataBytes.length)];
         int len = cipher.processBytes(dataBytes, 0, dataBytes.length, output, 0);
         try {

common/src/main/java/me/alexdevs/classicPeripherals/peripherals/crypto/AbstractCryptographicAcceleratorPeripheral.java

@@ -107,6 +107,9 @@ public final String decodeBase64(String data) {
 
     @LuaFunction
     public final String encryptAes(String data, String key, String iv) throws LuaException {
+        CryptoUtils.validateLength(1, key.length(), 16, 24, 32);
+        CryptoUtils.validateLength(2, iv.length(), 16);
+
         try {
             return Crypto.encryptAes(data, key, iv);
         } catch (BadPaddingException e) {
@@ -116,6 +119,9 @@ public final String encryptAes(String data, String key, String iv) throws LuaExc
 
     @LuaFunction
     public final String decryptAes(String data, String key, String iv) throws LuaException {
+        CryptoUtils.validateLength(1, key.length(), 16, 24, 32);
+        CryptoUtils.validateLength(2, iv.length(), 16);
+        
         try {
             return Crypto.decryptAes(data, key, iv);
         } catch (BadPaddingException e) {

common/src/main/java/me/alexdevs/classicPeripherals/utils/CryptoUtils.java

@@ -2,6 +2,9 @@
 
 import dan200.computercraft.api.lua.LuaException;
 
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
 public class CryptoUtils {
     public static void validateKey(String key) throws LuaException {
         if (key != null && key.length() != 32) {
@@ -14,4 +17,18 @@ public static void validateSignature(String key) throws LuaException {
             throw new LuaException("Invalid signature length, expected 64 bytes.");
         }
     }
+
+    public static void validateLength(int index, int value, int... lengths) throws LuaException {
+        for (int len : lengths) {
+            if (value == len) {
+                return;
+            }
+        }
+
+        var expectedValues = IntStream.of(lengths)
+                .mapToObj(Integer::toString)
+                .collect(Collectors.joining(", "));
+
+        throw new LuaException("bad argument length #" + (index + 1) + " (expected " + expectedValues + ", got " + value + ")");
+    }
 }