MD5加密的两种方法，一个是类似ASP中用的MD5加密方法，一个是类似JS中用的hex_md5加密方法

 需要引用using System.Security.Cryptography;

方法一：类似ASP中的MD5加密方法

        /// <summary>
        /// 获取MD5加密后的字符串
        /// </summary>
        /// <param name="SourceString">需要加密的字符串</param>
        /// <param name="EncLen">加密数据长度，16位或者32位</param>
        /// <returns></returns>
        public static string MD5(string SourceString, int EncLen)
        {
            MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
            byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(SourceString));
            StringBuilder sBuilder = new StringBuilder();
            int i = 0;
            if (EncLen == 16)
            {
                for (i = 4; i <= 11; i++)
                {
                    sBuilder.Append(data[i].ToString("x2"));
                }
            }
            else
            {
                for (i = 0; i <= 15; i++)
                {
                    sBuilder.Append(data[i].ToString("x2"));
                }
            }
            return sBuilder.ToString();
        }

方法二：类似JS中的hex_md5加密方法

        //JavaScript的hex_md5一样
        public static string CalculateMD5Hash(string input)
        {
            // step 1, calculate MD5 hash from input
            MD5 md5 = System.Security.Cryptography.MD5.Create();
            byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
            byte[] hash = md5.ComputeHash(inputBytes);

            // step 2, convert byte array to hex string
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < hash.Length; i++)
            {
                sb.Append(hash[i].ToString("X2"));
            }
            return sb.ToString();
        }