Md5加密秘钥加密哈希加密

    public class EncryptClass
    {
        /// <summary>
        /// 返回MD5加密字符串
        /// </summary>
        /// <param name="EncString"></param>
        /// <returns></returns>
        public static string GetMd5String(string EncString)
        {
            return FormsAuthentication.HashPasswordForStoringInConfigFile(EncString + "Hello CSH", "md5");
        }

        // using System.Security.Cryptography;  
        public static string GetMd5Hash(String input)
        {
            if (input == null)
            {
                return null;
            }

            MD5 md5Hash = MD5.Create();

            // 将输入字符串转换为字节数组并计算哈希数据  
            byte[] data = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input));

            // 创建一个 Stringbuilder 来收集字节并创建字符串  
            StringBuilder sBuilder = new StringBuilder();

            // 循环遍历哈希数据的每一个字节并格式化为十六进制字符串  
            for (int i = 0; i < data.Length; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));
            }

            // 返回十六进制字符串  
            return sBuilder.ToString();
        }

        #region 密钥加密解密
        //方法 
        //加密方法 
        public static string Encrypt(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //把字符串放到byte数组中 
            //原来使用的UTF8编码，我改成Unicode编码了，不行 
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            //byte[] inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt); 

            //建立加密对象的密钥和偏移量 
            //原文使用ASCIIEncoding.ASCII方法的GetBytes方法 
            //使得输入密码必须输入英文文本 
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            //Write the byte array into the crypto stream 
            //(It will end up in the memory stream) 
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //Get the data back from the memory stream, and into a string 
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                //Format as hex 
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }

        //解密方法 
        public static string Decrypt(string pToDecrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            //Put the input string into the byte array 
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            //建立加密对象的密钥和偏移量，此值重要，不能修改 
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            //Flush the data through the crypto stream into the memory stream 
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();

            //Get the decrypted data back from the memory stream 
            //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象 
            StringBuilder ret = new StringBuilder();

            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }




        #endregion
    }

Encrypt和Decrypt  加密算法指定键的大小对于此算法无效：是因为key值必须是8位64个字节，因此在输入时给予控制，注意key为Encoding.UTF8  必须输入8位秘钥否则报错