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