java - 即使输入相同，AES/CBC/NoPadding 是否会生成两个不同的密文？

Question

使用以下代码，我正在执行 AES 加密操作，我在不同的实例中传递相同的输入，但我得到了不同的密码。为什么会出现这种情况？

 public static byte[] encrypt(byte[] plainText, byte[] key) 
    {
  byte[] passwordKey128 = Arrays.copyOfRange(key, 0, 16);
  SecretKeySpec secretKey = new SecretKeySpec(passwordKey128, "AES");
  Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
  cipher.init(Cipher.ENCRYPT_MODE, secretKey);
  byte[] cipherText = cipher.doFinal(plainText);
  return cipherText;
 }

输入是

 encrypt(new byte[]{-17, -60, -70, 24, 80, 35, 2, -62, -79, 19, -55, -50, -62, -69, -80, -96} ,new byte[]{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} );

在一种情况下，密码是 - [0, 91, -96, 80, -44, -93, 107, 62, 4, -10, 103, 119, 109, 4, 25, 68]

在另一个例子中，密码是 - [87, 109, 20, 69, 18, 6, 103, 92, -57, 62, -41, -103, -18, -19, 74, 87]

可能是什么原因？

Answer 1

CBC 模式需要 IV，如果未指定，init 方法可能会生成随机 IV(来自 the documentation):

If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an InvalidKeyException if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using getParameters or getIV (if the parameter is an IV).

为了避免显式指定 IV。