Java TripleDES PKCS5Padding 解密到 C# - 错误数据/填充错误

Question

我正在尝试为以下 Java 代码编写等效的 C#：

protected static final String DES_ECB_PKCS5PADDING = "DESede/ECB/PKCS5Padding";

 public static String decryptValueDirect(String value, String key)
            throws NoSuchAlgorithmException, NoSuchPaddingException,
            GeneralSecurityException, IllegalBlockSizeException,
            BadPaddingException {
        byte[] bytes = Base64.decodeBase64(value);
        Cipher cipher = Cipher.getInstance(DES_ECB_PKCS5PADDING);
        cipher.init(Cipher.DECRYPT_MODE, convertSecretKey(key.getBytes()));
        byte[] decryptedValue = cipher.doFinal(bytes);

        String nstr =  new String(decryptedValue);
        return nstr;
    }
protected static SecretKey convertSecretKey(byte[] encryptionKey) throws GeneralSecurityException {
        if (encryptionKey == null || encryptionKey.length == 0)
            throw new IllegalArgumentException("Encryption key must be specified");

        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(TRIPLEDES);
        KeySpec keySpec = new DESedeKeySpec(encryptionKey);
        return keyFactory.generateSecret(keySpec);
    }

源文本经过 base64 编码，然后加密，然后进行 base64 编码以便在 rabbit 队列上传输。我们处理加密的供应商在 Java 中提供了以上用于解密的内容，但对 C# 一无所知。

加密端唯一的输入是密钥，一个随机字符串。我们在开发环境中对 encryption/decryption 012345678901234567890123456789 使用相同的字符串。这是唯一的输入，没有盐、散列（我看到的）或 pw 迭代。唯一的要求是它至少有 24 个字符长。

下面是我的 C# 代码，这里是我的 fiddle 尝试。

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public class Program
{
    public static void Main()
    {
        //Message Data value
        //We are using encrypted multibyte.     
        string myData = @"ROE8oYeV7B6faUsvfIx0Xe55vSs9IR5DlWGRbSM+lmKmLcaJsA13VudwWlAEYtLUD8+nMXShky0grSxsk0Z9cQe5V45XnAIfUhnyzI9a0jtMFC8XnIZ5dbclPO/V73QnieIZDkbNV5cPo3BM+l79ai96KB/gkF3xuerFPxvWejtPyWbOyO+FfNyFps4gAYDITsYIAEH39VP4eipmQ5zc18BA39lajQ3UaVewSxz7H+x3Ooe2SzJT/TQWRkioJSEFwexqzkHiLOQ0MOCIVD9xTWpLYnsL3LMwyF6H8f0PY4Fc57LVGhvUZ7dsB9NWUAnmG3uqbsonNFVhuXyvJTWNyFOHwFzOMx6XDLJJFHGZhaHg2VrescfnpUtonQY08RgojBngyJNRqK8URAvI3bqKq8Y7F/9HmEtMIIQe6KuuTmU=";
        string myKey = "012345678901234567890123456789";//Development Env Key.
        Console.WriteLine("Decrypt1:");
        string s = Decrypt1(myData, myKey);
        Console.ReadLine();
    }

    public static string Decrypt1(string value, string decryptionKey)
    {
        string decryptString = "";
        TripleDESCryptoServiceProvider tDESalg = new TripleDESCryptoServiceProvider();
        MD5CryptoServiceProvider hashMD5Provider = new MD5CryptoServiceProvider();
        try
        {
            byte[] decodedData = Convert.FromBase64String(value);
            tDESalg.Mode = CipherMode.ECB;
            tDESalg.Padding = PaddingMode.PKCS7;//According to MS, same as PKCS5PADDING

            byte[] Key = hashMD5Provider.ComputeHash(Encoding.UTF8.GetBytes(decryptionKey));
            //byte[] IV = tDESalg.IV;
            byte[] IV = new byte[tDESalg.BlockSize / 8]; //The size of the IV property must be the same as the BlockSize property divided by 8

            var memoryStream = new MemoryStream(decodedData);
            var cryptoStream = new CryptoStream(memoryStream, tDESalg.CreateDecryptor(Key, IV), CryptoStreamMode.Read);
            var reader = new StreamReader(cryptoStream);
            decryptString = reader.ReadToEnd();
            byte[] decryptData = Convert.FromBase64String(decryptString);
        }
        catch (Exception e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message + e.StackTrace);
            return null;
        }

        return decryptString;
    }

}

搜索似乎指向相同的答案，密钥、编码...都必须相同。我只是不知道所提供的 Java 来源的等价物是什么。 :) 任何建议都会有所帮助。

Answer 1

MD5 有一个 16 字节的输出，三重 DES (3DES) 需要一个 24 字节的密钥。密钥大小不匹配。

C# 和 Java 密钥派生有很大不同：

C#:
byte[] Key = hashMD5Provider.ComputeHash(Encoding.UTF8.GetBytes(decryptionKey));
returns 16-bytes.

Java:
SecretKeyFactory.getInstance(TRIPLEDES)
returns 24-bytes.

有一个密钥选项 (2TDEA)，其中使用 16 字节密钥，前 8 字节将被复制以创建最后 8 字节。 NIST 已弃用此选项。

一些实现会接受 16 字节的密钥并将密钥扩展到 24 字节，有些不会。您应该向 3DES 提供所有 24 字节，不要依赖实现来创建 24 字节密钥。

Note: The question was updated so it is not clear that the the actual encrytpion key is derived.

Java TripleDES PKCS5Padding 解密到 C# - 错误数据/填充错误

Java TripleDES PKCS5Padding decryption to C# - bad data / padding error

encryption

cryptography

tripledes