C#

#region ===========================DES算法===================================

private static string key = "key";
/// <summary>
/// 默认加密方法
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public static string DESEncrypt(string text)
{
return DESEncrypt(text, key);
}
/// <summary>
/// DES加密方法
/// </summary>
/// <param name="text">明文</param>
/// <param name="sKey">密钥</param>
/// <returns>加密后的密文</returns>
public static string DESEncrypt(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);
}
ms.Dispose();
cs.Dispose();
return ret.ToString();

}
/// <summary>
/// DES解密方法，默认方法
/// </summary>
/// <param name="text">待加密明文</param>
/// <returns>加密后的密文</returns>
public static string DESDecrypt(string text)
{
return DESDecrypt(text,key);
}
/// <summary>
/// DES解密方法
/// </summary>
/// <param name="text">密文</param>
/// <param name="sKey">密钥</param>
/// <returns>解密后的明文</returns>
public static string DESDecrypt(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;
}
try
{
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();
string estring = Encoding.Default.GetString(ms.ToArray());
ms.Dispose();
cs.Dispose();
return estring;
}
catch
{
return "";
}

}
#endregion

#region ==============================MD5算法==================================
/// <summary>
/// 使用MD5算法求Hash散列
/// </summary>
/// <param name="text">明文</param>
/// <returns>散列值</returns>
public static string MD5Encrypt(string text)
{
return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(text, "MD5");
}
#endregion============================================================

#region =============================SHA1==============================

/// <summary>
/// 使用SHA1算法求Hash散列
/// </summary>
/// <param name="text">明文</param>
/// <returns>散列值</returns>
public static string SHA1Encrypt(string text)
{
return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(text, "SHA1");
}
#endregion=============================================================

}

本文来自：http://www.cnblogs.com/LYshuqian/archive/2013/02/20/2919152.html