为什么解密时出现“ BadPaddingException”？

Question

这是我的加密设置：

public static String encryptionAlgorithm = "AES";
public static short encryptionBitCount = 256;
public static int encryptionMessageLength = 176;
public static String hashingAlgorithm = "PBEWITHSHAAND128BITAES-CBC-BC";
       //PBEWithSHA256And256BitAES-CBC-BC"PBEWithMD5AndDES";//"PBKDF2WithHmacSHA1";
public static short hashingCount = 512;
public static String cipherTransformation = "AES/CBC/PKCS5Padding";

这是我要解密的代码：

public byte[] readMessage () throws Exception
{
    byte[] iv = new byte[16];
    byte[] message = new byte[EncryptionSettings.encryptionMessageLength];

    try
    {
        // read IV from stream
        if (stream.read(iv) != 16)
            throw new Exception("Problem receiving full IV from stream");
    }
    catch (final IOException e)
    {
        throw new Exception("Unable to read IV from stream");
    }

    try
    {
        cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
    }
    catch (final InvalidKeyException e)
    {
        throw new Exception("Invalid key");
    }
    catch (final InvalidAlgorithmParameterException e)
    {
        throw new Exception("Invalid algorithm parameter");
    }

    try
    {
        //read message from stream
        if (stream.read(message) != EncryptionSettings.encryptionMessageLength)
             throw new Exception("Problem receiving full encrypted message from stream");
    }
    catch (final IOException e)
    {
        throw new Exception("Unable to read message from stream");
    }

    try
    {
        return cipher.doFinal(message); //decipher message and return it.
    }
    catch (IllegalBlockSizeException e)
    {
        throw new Exception("Unable to decrypt message due to illegal block size - "
                          + e.getMessage());
    }
    catch (BadPaddingException e)
    {
        throw new Exception("Unable to decrypt message due to bad padding - "
                            + e.getMessage());
    }
}

这是我要加密的代码：

public void writeMessage (final byte[] message) throws Exception
{
    try
    {
        // write iv
        byte b[] = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
        System.out.println(b.length);
        stream.write(b);
    }
    catch (final InvalidParameterSpecException e) 
    {
        throw new Exception("Unable to write IV to stream due to invalid"+
                            " parameter specification");
    }
    catch (final IOException e)
    {
        throw new Exception("Unable to write IV to stream");
    }

    try
    {
        // write cipher text
        byte b[] = cipher.doFinal(message);
        System.out.println(b.length);
        stream.write(b);
    }
    catch (final IllegalBlockSizeException e)
    {
        throw new Exception("Unable to write cipher text to stream due to "+
                            "illegal block size");
    }
    catch (final BadPaddingException e)
    {
        throw new Exception("Unable to write cipher text to stream due to " +
                            "bad padding");
    }
    catch (final IOException e)
    {
        throw new Exception("Unable to write cipher text to stream");
    }
}

错误： Unable to decrypt message due to bad padding - null.

解密时出现BadPaddingException异常，为什么？该消息正好是168个字符，在填充后为176个字符（可被16整除）

Answer 1

从我最初的评论：

一种典型的情况是密钥与另一侧使用的密钥不同。这是最可能的原因，但是您可能还想检查处理流的方式，因为您确实缺少.close（）以及可能缺少.flush（）语句。您还假定始终可以将所有数据读入缓冲区，但实际情况并非如此。

密钥确实计算不正确。