MD5加密，解密

using System;
using System.Collections.Generic;
using System.Text;
using System.Globalization;
using System.Security.Cryptography;
using System.IO;
namespace WindowsApplication2
{
    class DES
    {
        // 创建Key
        public string GenerateKey()
        {
            DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();
            return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
        }
        ///MD5加密
        public string MD5Encrypt(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            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);
            cs.Write(inputByteArray, , inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();

        }

        ///MD5解密
        public string MD5Decrypt(string pToDecrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            byte[] inputByteArray = new byte[pToDecrypt.Length / ];
            for (int x = ; x < pToDecrypt.Length / ; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * , ), ));
                inputByteArray[x] = (byte)i;
            }

            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);
            cs.Write(inputByteArray, , inputByteArray.Length);
            cs.FlushFinalBlock();

            StringBuilder ret = new StringBuilder();

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

    }
}