程序加密类SafeUtil

该类使用著名的加密算法DES来实现网站信息的加密与解密程序。DES属于一种私钥加密，也称为对称加密。所谓对称加密，就是使用一个密钥加密，也必须使用该密钥进行解密。

私钥加密算法的速度非常快，它特别适合用于对较大的数据流执行加密。

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Web;
  5 using System.Security.Cryptography;
  6 using System.Text;
  7 using System.IO;
  8 
  9 namespace ECExp
 10 {
 11     public class SafeUtil
 12     {
 13         private string iv = "12345678";//种子
 14         private string key = "12345678";//密钥
 15         private Encoding encoding = new UnicodeEncoding();
 16         private DES des = null;
 17 
 18         /// <summary>
 19         /// 构造函数
 20         /// </summary>
 21         public SafeUtil()
 22         {
 23             des = new DESCryptoServiceProvider();
 24         }
 25 
 26         /// <summary>
 27         /// 设置密钥
 28         /// </summary>
 29         public string EncryptKey
 30         {
 31             set
 32             {
 33                 this.key = value;
 34             }
 35         }
 36 
 37         /// <summary>
 38         /// 设置或获取密文编码格式（默认为UTF-8）
 39         /// </summary>
 40         public Encoding EncodingMode
 41         {
 42             get { return this.encoding; }
 43             set { this.encoding = value; }
 44         }
 45 
 46         /// <summary>
 47         /// 加密字符串并返回加密后的结果
 48         /// </summary>
 49         /// <param name="str">要加密的字符串</param>
 50         /// <returns></returns>
 51         public string EncryptString(string str)
 52         {
 53             byte[] ivb = Encoding.ASCII.GetBytes(this.iv);
 54             byte[] keyb = Encoding.ASCII.GetBytes(this.key);//得到加密密钥
 55             byte[] toEncrypt = this.EncodingMode.GetBytes(str);//得到要加密的内容
 56             byte[] encrypted;
 57 
 58             //DES加密工具类
 59             ICryptoTransform encryptor = des.CreateEncryptor(keyb, ivb);
 60             MemoryStream msEncrypt = new MemoryStream();
 61             CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
 62 
 63             csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
 64             csEncrypt.FlushFinalBlock();
 65             encrypted = msEncrypt.ToArray();
 66             csEncrypt.Close();
 67             msEncrypt.Close();
 68             return Convert.ToBase64String(encrypted);
 69         }
 70 
 71         /// <summary>
 72         /// 解密给定的字符串
 73         /// </summary>
 74         /// <param name="str">要解密的字符，Base64</param>
 75         /// <returns></returns>
 76         public string DecryptString(string str)
 77         {
 78             byte[] ivb = Encoding.ASCII.GetBytes(this.iv);
 79             byte[] keyb = Encoding.ASCII.GetBytes(this.key);
 80             byte[] toDecrypt = Convert.FromBase64String(str);
 81             byte[] deCrypted = new byte[toDecrypt.Length];
 82 
 83             ICryptoTransform deCryptor = des.CreateDecryptor(keyb, ivb);
 84             MemoryStream msDecrypt = new MemoryStream(toDecrypt);
 85             CryptoStream csDecrypt = new CryptoStream(msDecrypt, deCryptor, CryptoStreamMode.Read);
 86 
 87             try
 88             {
 89                 csDecrypt.Read(deCrypted, 0, deCrypted.Length);
 90             }
 91             catch (Exception err)
 92             {
 93 
 94                 throw new ApplicationException(err.Message);
 95             }
 96             finally
 97             {
 98                 try
 99                 {
100                     msDecrypt.Close();
101                     csDecrypt.Close();
102                 }
103                 catch (Exception)
104                 {
105                     
106                 }
107             }
108             return this.EncodingMode.GetString(deCrypted);
109         }
110     }
111 }

如何使用：

            SafeUtil safeutil = new SafeUtil();
            string str = safeutil.EncryptString("456123");
            lblText.Text = str;
            string str2 = safeutil.DecryptString(safeutil.EncryptString("456123"));
            Label1.Text = str2;