为什么AES解密会产生空结果？

Question

Encryption done in java using AES and wanted to decrypt in Python, but the result is empty in python (no errors). See the code before marking as duplicate. I want to detect problem in my code.

java encryption code:

public static String encrypt(String plainText)  throws Exception {
    KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
    keyGenerator.init(128);

    SecretKey secretKey = keyGenerator.generateKey();
    String keyStr = Base64.encodeToString(secretKey.getEncoded(), Base64.NO_WRAP);
    byte[] initVector = new byte[16];
    (new Random()).nextBytes(initVector);

    IvParameterSpec iv = new IvParameterSpec(initVector);
    SecretKeySpec skeySpec = new SecretKeySpec(secretKey.getEncoded(), "AES");
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);

    byte[] plainTextByte = plainText.getBytes();
    byte[] encryptedByte = cipher.doFinal(plainTextByte);
    byte[] messagebytes = new byte[initVector.length + encryptedByte.length];

    System.arraycopy(initVector, 0, messagebytes, 0, 16);
    System.arraycopy(encryptedByte, 0, messagebytes, 16, encryptedByte.length);

    return Base64.encodeToString(messagebytes, Base64.NO_WRAP);
}

Python code

def decrypt(key, message):
    """
    Input encrypted bytes, return decrypted bytes, using iv and key
    """

    byte_array = message.encode("UTF-8")

    iv = byte_array[0:16] # extract the 16-byte initialization vector

    messagebytes = byte_array[16:] # encrypted message is the bit after the iv

    cipher = AES.new(key.encode("UTF-8"), AES.MODE_CBC, iv)

    decrypted_padded = cipher.decrypt(messagebytes)

    decrypted = unpad(decrypted_padded)

    return decrypted.decode("UTF-8");

Answer 1

I see that the Java is explicitly encoding the string as Base 64 at return Base64.encodeToString(messagebytes, Base64.NO_WRAP);

But i see that you are again encoding in python byte_array = message.encode("UTF-8") where in you will have to decode the encrypted message

# Standard Base64 Decoding
decodedBytes = base64.b64decode(encodedStr)
decodedStr = str(decodedBytes, "utf-8")

And only then Decrypt the decoded message.