基础才是重中之重~BouncyCastle实现的DES3加密~java通用

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。

加密过程

• 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

解密过程

• 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

原码

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

        /// <summary>
        /// 生成一个16位的key.
        /// </summary>
        /// <returns></returns>
        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);
        }

        /// <summary>
        /// 做一个16位的md5加密，防止被其它人解析.
        /// </summary>
        /// <param name="Source"></param>
        /// <returns></returns>
        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;
        }

        /// <summary>
        /// 使用DES3加密
        /// </summary>
        /// <param name="plainText">需要加密的字符串</param>
        /// <param name="keys">加密字符串的密钥</param>
        /// <returns>加密后的字符串</returns>
        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;
        }

        /// <summary>
        /// 使用DES3解密
        /// </summary>
        /// <param name="cipherText">需要加密的字符串</param>
        /// <param name="keys">加密字符串的密钥</param>
        /// <returns>解密后的字符串</returns>
        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;
        }
    }

调用

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

结果