DES加密/解密类。

using System.Security.Cryptography;   //用的类


     /// <summary>
    /// DES加密/解密类。
    /// </summary>
    public class DESEncrypt
    {
        public DESEncrypt()
        {            
        }

        #region ========加密======== 
 
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="Text"></param>
        /// <returns></returns>
        public static string Encrypt(string Text) 
        {
            return Encrypt(Text, "litianping");
        }
        /// <summary> 
        /// 加密数据 
        /// </summary> 
        /// <param name="Text"></param> 
        /// <param name="sKey"></param> 
        /// <returns></returns> 
        public static string Encrypt(string Text,string sKey) 
        { 
            DESCryptoServiceProvider des = new DESCryptoServiceProvider(); 
            byte[] inputByteArray; 
            inputByteArray=Encoding.Default.GetBytes(Text); 
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
            System.IO.MemoryStream ms=new System.IO.MemoryStream(); 
            CryptoStream cs=new CryptoStream(ms,des.CreateEncryptor(),CryptoStreamMode.Write); 
            cs.Write(inputByteArray,0,inputByteArray.Length); 
            cs.FlushFinalBlock(); 
            StringBuilder ret=new StringBuilder(); 
            foreach( byte b in ms.ToArray()) 
            { 
                ret.AppendFormat("{0:X2}",b); 
            } 
            return ret.ToString(); 
        } 

        #endregion
        
        #region ========解密======== 
   
 
        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="Text"></param>
        /// <returns></returns>
        public static string Decrypt(string Text) 
        {
            return Decrypt(Text, "litianping");
        }
        /// <summary> 
        /// 解密数据 
        /// </summary> 
        /// <param name="Text"></param> 
        /// <param name="sKey"></param> 
        /// <returns></returns> 
        public static string Decrypt(string Text,string sKey) 
        { 
            DESCryptoServiceProvider des = new DESCryptoServiceProvider(); 
            int len; 
            len=Text.Length/2; 
            byte[] inputByteArray = new byte[len]; 
            int x,i; 
            for(x=0;x<len;x++) 
            { 
                i = Convert.ToInt32(Text.Substring(x * 2, 2), 16); 
                inputByteArray[x]=(byte)i; 
            } 
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
            System.IO.MemoryStream ms=new System.IO.MemoryStream(); 
            CryptoStream cs=new CryptoStream(ms,des.CreateDecryptor(),CryptoStreamMode.Write); 
            cs.Write(inputByteArray,0,inputByteArray.Length); 
            cs.FlushFinalBlock(); 
            return Encoding.Default.GetString(ms.ToArray()); 
        } 
 
        #endregion 


    }