MD5加密解密帮助类

using System;
using System.Security.Cryptography;
using System.Text;
namespace Maticsoft.DBUtility
{
	/// <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 

	}
}