Added test for ChachaPolyCipher without AAD

src/main/java/com/hierynomus/sshj/transport/cipher/ChachaPolyCipher.java

@@ -155,7 +155,7 @@ public void update(byte[] input, int inputOffset, int inputLen) {
             }
         } else {
             try {
-                cipher.update(input, AAD_LENGTH, inputLen, input, AAD_LENGTH);
+                cipher.update(input, inputOffset, inputLen, input, inputOffset);
             } catch (GeneralSecurityException e) {
                 throw new SSHRuntimeException("ChaCha20 encryption failed", e);
             }

src/test/java/com/hierynomus/sshj/transport/ChachaPolyCipherTest.java

@@ -70,6 +70,28 @@ public void testEncryptDecrypt() {
         }
     }
 
+    @Test
+    public void testEncryptDecryptWithoutAAD() {
+        final Cipher encryptionCipher = FACTORY.create();
+        final byte[] key = new byte[encryptionCipher.getBlockSize()];
+        Arrays.fill(key, (byte) 1);
+        encryptionCipher.init(Cipher.Mode.Encrypt, key, new byte[0]);
+
+        final byte[] plaintextBytes = PLAINTEXT.getBytes(StandardCharsets.UTF_8);
+        final byte[] message = new byte[plaintextBytes.length + POLY_TAG_LENGTH];
+        System.arraycopy(plaintextBytes, 0, message, 0, plaintextBytes.length);
+
+        encryptionCipher.update(message, 0, plaintextBytes.length);
+
+        final Cipher decryptionCipher = FACTORY.create();
+        decryptionCipher.init(Cipher.Mode.Decrypt, key, new byte[0]);
+        decryptionCipher.update(message, 0, plaintextBytes.length);
+
+        final byte[] decrypted = Arrays.copyOfRange(message, 0, plaintextBytes.length);
+        final String decoded = new String(decrypted, StandardCharsets.UTF_8);
+        assertEquals(PLAINTEXT, decoded);
+    }
+
     @Test
     public void testCheckOnUpdateParameters() {
         Cipher cipher = FACTORY.create();