Question

我正在尝试将此C＃代码转换为Python（2.7）。问题是python代码解密的结果是错误的。 IV和关键是正确的。

我找到了许多谈论Python和C＃的主题，但我没有找到答案。

C＃加密：

class Tracer
{
    private static readonly int BlockBitSize = 128;
    private static readonly int KeyBitSize = 256;

    /// <summary>
    /// Encrypte
    /// </summary>
    internal static byte[] In(byte[] plainBytes, byte[] uid)
    {
        using (var sha = new SHA512Managed())
        {
            var hash = sha.ComputeHash(uid);
            return In(plainBytes, hash.Skip(32).Take(32).ToArray(), hash.Take(16).ToArray());
        }
    }

    /// <summary>
    /// Encrypte
    /// </summary>
    internal static byte[] In(byte[] plainBytes, byte[] key, byte[] iv)
    {
        if (key == null || key.Length != KeyBitSize / 8)
            throw new ArgumentException(String.Format("Key needs to be {0} bit!", KeyBitSize), "key");
        if (iv == null || iv.Length != BlockBitSize / 8)
            throw new ArgumentException(String.Format("IV needs to be {0} bit!", BlockBitSize), "iv");

        using (AesManaged aes = new AesManaged())
        {
            aes.KeySize = KeyBitSize;
            aes.BlockSize = BlockBitSize;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.None;

            using (ICryptoTransform encrypter = aes.CreateEncryptor(key, iv))
                using (MemoryStream cipherStream = new MemoryStream())
                {
                    using (CryptoStream cryptoStream = new CryptoStream(cipherStream, encrypter, CryptoStreamMode.Write))
                    {
                        cryptoStream.Write(plainBytes, 0, plainBytes.Length);
                        cryptoStream.FlushFinalBlock();
                    }
                    return cipherStream.ToArray();
                }
        }
    }

    /// <summary>
    /// Décrypte
    /// </summary>
    internal static byte[] Out(byte[] cipherBytes, byte[] uid)
    {
        using (var sha = new SHA512Managed())
        {
            var hash = sha.ComputeHash(uid);
            return Out(cipherBytes, hash.Skip(32).Take(32).ToArray(), hash.Take(16).ToArray());
        }
    }

    /// <summary>
    /// Décrypte
    /// </summary>
    internal static byte[] Out(byte[] cipherBytes, byte[] key, byte[] iv)
    {
        if (key == null || key.Length != KeyBitSize / 8)
            throw new ArgumentException(String.Format("Key needs to be {0} bit!", KeyBitSize), "key");
        if (iv == null || iv.Length != BlockBitSize / 8)
            throw new ArgumentException(String.Format("IV needs to be {0} bit!", BlockBitSize), "iv");

        using (AesManaged aes = new AesManaged())
        {
            aes.KeySize = KeyBitSize;
            aes.BlockSize = BlockBitSize;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.None;

            using (ICryptoTransform decrypter = aes.CreateDecryptor(key, iv))
                using (MemoryStream plainStream = new MemoryStream())
                {
                    using (var decrypterStream = new CryptoStream(plainStream, decrypter, CryptoStreamMode.Write))
                        using (var binaryWriter = new BinaryWriter(decrypterStream))
                        {
                            //Decrypt Cipher Text from Message
                            binaryWriter.Write(cipherBytes, 0, cipherBytes.Length);
                        }
                    //Return Plain Text
                    return plainStream.ToArray();
                }
        }
    }
}

Python解密

def AESdecrypt(ciphertext, UID):

    from Crypto.Cipher import AES

    digest = hashlib.sha512(UID).hexdigest()

    iv = BitArray(hex=digest[:32])

    key = BitArray(hex=digest[64:128])

    block40Str = BitArray(hex=ciphertext[1].encode('hex'))

    cipherSpec = AES.new(key.bytes, AES.MODE_CBC, iv.bytes)
    plaintextWithPadding = cipherSpec.decrypt(block40Str.bytes)

注意：抱歉我的英文

感谢您的帮助！

编辑：Python中的AES解密返回64个字符，这是错误的。原始明文是32。

EDIT2：更新了Python代码。解密函数现在返回32个字符，但仍然做错了

Answer 1

用于生成密钥的摘要和iv是使用正确的数据生成的，但是以字符串形式生成。相反，C＃使用数据的ByteArray生成摘要。感谢BitArray Python library，我解决了我的问题：

新的Python代码：

def AESdecrypt(ciphertext, UID):

    from Crypto.Cipher import AES

    UIDBytes = BitArray(hex=UID)
    digest = hashlib.sha512(UIDBytes.bytes).hexdigest()

    iv = BitArray(hex=digest[:32])

    key = BitArray(hex=digest[64:128])

    cipherSpec = AES.new(key.bytes, AES.MODE_CBC, iv.bytes)
    plaintextWithoutPadding = cipherSpec.decrypt(ciphertext[1])

C＃到python AES CBC没有填充

1 个答案: