个人收藏C#Des加解密类

C#Des加解密帮助类，实现了加密key的不固定，实现原理其实就是将key进行md5加密，然后在进行截取前八位，当成新的密钥，然后再进行Des加密

using System;
using System.Security.Cryptography;  
using System.Text;
namespace Common.DES
{
 /// <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, "xiaoxia");
  }
  /// <summary> 
  /// 加密数据 
  /// </summary> 
  /// <param name="Text">明文</param> 
  /// <param name="sKey">没有限定长度</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, "liyanling");
  }
  /// <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


 }
}