为什么我在解密时会收到'BadPaddingException'？ [英] Why am I getting 'BadPaddingException' when decrypting?

问题描述

以下是我的加密设置：

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());
    }
}

这是我的加密代码：

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：无法解密由于填充错误而导致的消息 - null。

我在解密时遇到BadPaddingException，为什么？消息正好是168个字符，填充后为176（可被16整除）

I am getting a BadPaddingException when decrypting, why? The message is exactly 168 characters which is 176 after padding (divisible by 16)

推荐答案

从我最初的评论：

典型情况是密钥与另一方使用的密钥不同。这是最可能的原因，但您可能还想检查处理流的方式，因为您确实缺少.close（）和可能的.flush（）语句。您还假设您始终可以将所有数据读入缓冲区，但情况可能并非如此。

A typical scenario is one where the key is different from the one used at the other side. This is the most probable cause, but you might also want to check the way you handle streams, because you really lack .close() and possibly .flush() statements. You also assume that you always can read all the data into the buffer, which may not be the case.

密钥确实计算错误。

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