学步园

//名称空间  
using  System;  
using  System.Security.Cryptography;  
using  System.IO;  
using  System.Text;

    /**/
    /// <summary>
    ///  DES算法描述简介：
    ///  DES是Data Encryption Standard（数据加密标准）的缩写。它是由IBM公司研制的一种加密算法，
    /// 美国国家标准局于1977年公布把它作为非机要部门使用的数据加密标准；
    /// 它是一个分组加密算法，他以64位为分组对数据加密。
    /// 同时DES也是一个对称算法：加密和解密用的是同一个算法。
    /// 它的密匙长度是56位（因为每个第8 位都用作奇偶校验），
    /// 密匙可以是任意的56位的数，而且可以任意时候改变．
    /// </summary>
    //默认密钥向量
    private static byte[] Keys ={ 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

    /// <summary>   
    /// DES加密字符串   
    /// </summary>   
    /// <param name="encryptString">待加密的字符串</param>   
    /// <param name="encryptKey">加密密钥,要求为8位</param>   
    /// <returns>加密成功返回加密后的字符串，失败返回源串</returns> 
    public static string EncryptDES(string encryptString, string encryptKey)
    {
        try
        {
            byte[] Key = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] IV = Keys;
            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(Key, IV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }
        catch
        {
            return encryptString;
        }
    }

    /// <summary>   
    /// DES解密字符串   
    /// </summary>   
    /// <param name="decryptString">待解密的字符串</param>   
    /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>   
    /// <returns>解密成功返回解密后的字符串，失败返源串</returns>  
    public static string DescryptDES(string descryptString, string descryptKey)
    {
        try
        {
            byte[] Key = Encoding.UTF8.GetBytes(descryptKey.Substring(0,8));
            byte[] IV = Keys;
            byte[] inputByteArray = Convert.FromBase64String(descryptString);
            DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(Key, IV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Encoding.UTF8.GetString(mStream.ToArray());
        }
        catch
        {
            return descryptString;
        }
    }

实例

    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write("加密字符:hello world!,密钥为:hongkaihua@126.com");
        string str = EncryptDES("hello world!","hongkaihua@126.com");
        Response.Write("DES加密:" + str);
        Response.Write("DES解密:" + DescryptDES(str, "hongkaihua@126.com"));

      }