Java通用BouncyCastle实现的DES3加密的方法

对于BouncyCastle类库（包）来说，他提供了很多加密算法，在与.net和java进行相互加解密过程中，得到了不错的应用，本文以DES3为例，来说一下DES3加解密的过程。

• 明文字符转为byte数组
• 对密钥进行处理，处理后一般为16或者24字节
• 对明文进行DES3加密，生成密文的byte数组
• 对密文byte数组进行base64的编码

• 对密文byte数组进行base64的解码
• 对密钥进行处理，处理后一般为16或者24字节
• 对解码后的byte数组进行DES3解密
• 对解密之后的byte数组进行Encoding.UTF8.GetString方法的调用生成明文字符串

 /// 

  /// DES3加密
  /// https://www.go4expert.com/articles/bouncy-castle-net-implementation-triple-t24829/
  /// 
  public class BouncyCastleHelper
  {
    static IBlockCipher engine = new DesEngine();

    /// 

    /// 生成一个16位的key.
    /// 
    /// 
    public string GenerateDES3Key()
    {
      CipherKeyGenerator cipherKeyGenerator = new CipherKeyGenerator();
      cipherKeyGenerator.Init(new KeyGenerationParameters(new SecureRandom(), 192));
      //192 specifies the size of key in bits i.e 24 bytes 
      var keyDES3 = cipherKeyGenerator.GenerateKey();
      BigInteger bigInteger = new BigInteger(keyDES3);
      return bigInteger.ToString(16);
    }

    /// 

    /// 做一个16位的md5加密，防止被其它人解析.
    /// 
    /// 
    /// 
    static byte[] GetMd5Digest(string Source)
    {
      var msgBytes = Encoding.UTF8.GetBytes(Source);
      var md5Digest = new MD5Digest();
      md5Digest.BlockUpdate(msgBytes, 0, msgBytes.Length);
      byte[] result = new byte[md5Digest.GetDigestSize()];
      md5Digest.DoFinal(result, 0);
      return result;
    }

    /// 

    /// 使用DES3加密
    /// 
    /// 需要加密的字符串
    /// 加密字符串的密钥
    /// 加密后的字符串
    public static string Encrypt(string plainText, string keys)
    {
      byte[] ptBytes = Encoding.UTF8.GetBytes(plainText);
      byte[] rv = Encrypt(ptBytes, keys);
      // 密文转为base64字符串 
      return Convert.Tobase64String(rv);
    }

    static byte[] Encrypt(byte[] ptBytes, string keys)
    {

      byte[] key = GetMd5Digest(keys);
      BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new DesEdeEngine());
      cipher.Init(true, new KeyParameter(key));
      byte[] rv = new byte[cipher.GetOutputSize(ptBytes.Length)];
      int tam = cipher.ProcessBytes(ptBytes, 0, ptBytes.Length, rv, 0);
      cipher.DoFinal(rv, tam);
      return rv;
    }

    /// 

    /// 使用DES3解密
    /// 
    /// 需要加密的字符串
    /// 加密字符串的密钥
    /// 解密后的字符串
    public static string Decrypt(string cipherText, string keys)
    {
      // 把密文进行base64的解码
      byte[] base64StringBytes = Convert.Frombase64String(cipherText);
      var rv = Decrypt(base64StringBytes, keys);
      // 字符数组转为明文字符串
      return Encoding.UTF8.GetString(rv, 0, rv.Length);
    }

    static byte[] Decrypt(byte[] cipherText, string keys)
    {
      byte[] key = GetMd5Digest(keys);
      BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new DesEdeEngine());
      cipher.Init(false, new KeyParameter(key));
      byte[] comparisonBytes = new byte[cipher.GetOutputSize(cipherText.Length)];
      int length = cipher.ProcessBytes(cipherText, comparisonBytes, 0);
      cipher.DoFinal(comparisonBytes, length); //Do the final block
      return comparisonBytes;
    }
  }

string result = BouncyCastleHelper.Encrypt("hello", "abc123");
Console.WriteLine("hello=" + result);
Console.WriteLine("plainText=" + BouncyCastleHelper.Decrypt(result, "abc123"));

结果

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