net cf HMAC MD5 加密

/// <summary>
        /// HMAC_MD5加密
        /// </summary>
        /// <param name="original">明文</param>
        /// <param name="key">密钥</param>
        /// <returns>返回加密的字符串</returns>
        public static string HMAC_MD5(string original, string key)
        {
            byte[] b_tmp;
            byte[] b_tmp1;
            if (key == null)
            {
                return null;
            }
            byte[] digest = new byte[512];
            byte[] k_ipad = new byte[64];
            byte[] k_opad = new byte[64];
            byte[] source = System.Text.ASCIIEncoding.ASCII.GetBytes(key);
            System.Security.Cryptography.MD5 shainner = new MD5CryptoServiceProvider();
            for (int i = 0; i < 64; i++)
            {
                k_ipad[i] = 0 ^ 0x36;
                k_opad[i] = 0 ^ 0x5c;
            }

            try
            {
                if (source.Length > 64)
                {
                    shainner = new MD5CryptoServiceProvider();
                    source = shainner.ComputeHash(source);
                }
                for (int i = 0; i < source.Length; i++)
                {
                    k_ipad[i] = (byte)(source[i] ^ 0x36);
                    k_opad[i] = (byte)(source[i] ^ 0x5c);
                }
                b_tmp1 = System.Text.ASCIIEncoding.ASCII.GetBytes(original);
                b_tmp = Adding(k_ipad, b_tmp1);
                shainner = new MD5CryptoServiceProvider();
                digest = shainner.ComputeHash(b_tmp);
                b_tmp = Adding(k_opad, digest);
                shainner = new MD5CryptoServiceProvider();
                digest = shainner.ComputeHash(b_tmp);
                return ByteToString(digest);
            }
            catch (Exception e)
            {
                throw e;
            }
        }

        /// <summary>
        /// 填充byte
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        private static byte[] Adding(byte[] a, byte[] b)
        {
            byte[] c = new byte[a.Length + b.Length];
            a.CopyTo(c, 0);
            b.CopyTo(c, a.Length);
            return c;
        }

        /// <summary>
        /// Byte To String
        /// </summary>
        /// <param name="buff"></param>
        /// <returns></returns>
        private static string ByteToString(byte[] buff)
        {
            string sbinary = "";

            for (int i = 0; i < buff.Length; i++)
            {
                sbinary += buff[i].ToString("X2"); // hex format
            }
            return (sbinary);
        }





//////////////////////  C# PC 只需要HMACMD5类就可以实现 ///////////////////////
        public byte[] EncodeString(byte[] key, byte[] source)
        {
            // Initialize the keyed hash object.
            HMACMD5 myhmacMD5 = new HMACMD5(key);
            // Compute the hash of the input file.
            return myhmacMD5.ComputeHash(source);
        }