C#设计模式之Strategy策略模式解决007大破密码危机问题示例

2020-01-24 00:28:27

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本文实例讲述了C#设计模式之Strategy策略模式解决007大破密码危机问题。分享给大家供大家参考，具体如下：

一、理论定义

策略模式定义了多套算法，这些算法在客户端可以任意切换。

二、应用举例

需求描述：话说007在皇家赌场赌牌，突然接到M夫人的急电，要求立刻去非洲寻找一个DES对称算法密钥，以破解敌人的军*情*机*密

1、(英*国*军*情*六*局)MI6=Military Intelligence 6 截获了一个非*洲战*区军*事*机*密文件，采用 MD5，RAS，加密，解密，都无法破解
后来发现，这文件被DES加密，必须找回对称密钥，才可以破解
2、邦德火速赶往非洲，目标只有一个：找到密钥。

三、具体编码

1.定义安全算法接口，里面有加密和解密方法

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Com.Design.Gof.Strategy{  public interface ISecurity  {    /// <summary>    /// 加密    /// </summary>    /// <param name="EncryptString">要加密字符串</param>    /// <returns></returns>    string Encrypt(string EncryptString);    /// <summary>    /// 解密    /// </summary>    /// <param name="EncryptString">要解密字符串</param>    /// <returns></returns>    string Decrypt(string EncryptString);  }}

2.MD5加密

using System;using System.Collections.Generic;using System.Text;using System.IO;using System.Security.Cryptography;namespace Com.Design.Gof.Strategy{  public class MD5 : ISecurity  {    /// <summary>    /// 用MD5加密    /// </summary>    /// <param name="s"></param>    /// <returns></returns>    public string Encrypt(string s)    {      byte[] b = Encoding.Default.GetBytes(s);      b = new MD5CryptoServiceProvider().ComputeHash(b);      string output = "";      for (int i = 0; i < b.Length; i++)        output += b[i].ToString("x").PadLeft(2, '0');      return output;    }    /// <summary>    /// MD5不提供解密    /// </summary>    /// <param name="EncryptString"></param>    /// <returns></returns>    public virtual string Decrypt(string EncryptString) { return string.Empty; }  }}

3.RSA加密

using System;using System.Text;using System.IO;using System.Security.Cryptography;using System.Security.Cryptography.X509Certificates;namespace Com.Design.Gof.Strategy{  public class RSA:ISecurity  {    private static readonly string key=new RSACryptoServiceProvider().ToXmlString(true);    /// <summary>    /// RSA加密函数    /// </summary>    /// <param name="xmlPublicKey">说明:KEY必须是XML的行式,返回的是字符串</param>    /// <param name="EncryptString"></param>    /// <returns></returns>    public string Encrypt(string s)    {      try      {        byte[] PlainTextBArray;        byte[] CypherTextBArray;        string Result;        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();        rsa.FromXmlString(key);        PlainTextBArray = (new UnicodeEncoding()).GetBytes(s);        CypherTextBArray = rsa.Encrypt(PlainTextBArray, false);        Result = Convert.ToBase64String(CypherTextBArray);        return Result;      }      catch { return "敌人密码太难破解，已经超过了RSA算法的承受能力，要采取分段加密"; }    }    /// <summary>    /// RSA解密函数    /// </summary>    /// <param name="xmlPrivateKey"></param>    /// <param name="DecryptString"></param>    /// <returns></returns>    public string Decrypt(string s)    {       try      {      byte[] PlainTextBArray;      byte[] DypherTextBArray;      string Result;      RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();      rsa.FromXmlString(key);      PlainTextBArray = Convert.FromBase64String(s);      DypherTextBArray = rsa.Decrypt(PlainTextBArray, false);      Result = (new UnicodeEncoding()).GetString(DypherTextBArray);      return Result;      }       catch { return "敌人密码太难破解，已经超过了RSA算法的承受能力，要采取分段解密"; }    }  }}

4.DES加密

using System;using System.Text;using System.IO;using System.Security.Cryptography; /// <summary>///MethodResult 的摘要说明/// </summary>namespace Com.Design.Gof.Strategy{  public class DES:ISecurity  {    private static byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF }; //密钥向量    //加密解密key    public string SymmetricKey { get; set; }    /// <summary>    /// 加密    /// </summary>    /// <param name="EncryptString">待加密的字符串</param>    /// <param name="EncryptKey">加密密钥</param>    /// <returns>加密成功返回加密后的字符串,失败返回源串</returns>    public string Encrypt(string EncryptString)    {      byte[] byKey = null;      byKey = System.Text.Encoding.UTF8.GetBytes(SymmetricKey.Substring(0, 8));      DESCryptoServiceProvider des = new DESCryptoServiceProvider();      byte[] inputByteArray = System.Text.Encoding.UTF8.GetBytes(EncryptString);      MemoryStream ms = new MemoryStream();      CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(byKey, IV), CryptoStreamMode.Write);      cs.Write(inputByteArray, 0, inputByteArray.Length);      cs.FlushFinalBlock();      return Convert.ToBase64String(ms.ToArray());    }    /// <summary>    /// 解密    /// </summary>    /// <param name="EncryptString">待解密的字符串</param>    /// <returns>解密成功返回解密后的字符串,失败返源串</returns>    public string Decrypt(string EncryptString)    {      byte[] byKey = null;      byte[] inputByteArray = new Byte[EncryptString.Length];      try      {        byKey = System.Text.Encoding.UTF8.GetBytes(SymmetricKey.Substring(0, 8));        DESCryptoServiceProvider des = new DESCryptoServiceProvider();        inputByteArray = Convert.FromBase64String(EncryptString);        MemoryStream ms = new MemoryStream();        CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write);        cs.Write(inputByteArray, 0, inputByteArray.Length);        cs.FlushFinalBlock();        System.Text.Encoding encoding = new System.Text.UTF8Encoding();        return encoding.GetString(ms.ToArray());      }      catch      {        return "";      }    }  }}

5.(英*国*军*情*六*局)MI6=Military Intelligence 6

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Com.Design.Gof.Strategy{  /// <summary>  /// (英*国*军*情*六*局)MI6=Military Intelligence 6  /// </summary>  public class MilitaryIntelligence6  {/// <summary>    /// 安全策略    /// </summary>    private ISecurity Security { get; set; }    /// <summary>    /// 被加密的军*情*信*息    /// </summary>    public string ClassifiedInfomation { get; set; }    /// <summary>    /// 加密    /// </summary>    /// <param name="s"></param>    /// <returns></returns>    public string Encrypt() {      return Security.Encrypt(ClassifiedInfomation);    }    /// <summary>    /// 解密    /// </summary>    /// <param name="s"></param>    /// <returns></returns>    public string Decrypt(string s) {      return Security.Decrypt(s);    }  }}

6.主函数

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Com.Design.Gof.Strategy;namespace Com.Design.Gof.Test{  class Program  {    /// <summary>    /// 往期 设计模式测试项目是一起的，想测试谁，就调用谁    /// </summary>    /// <param name="args"></param>    static void Main(string[] args)    {      MilitaryIntelligence6 MI6= new MilitaryIntelligence6      {        //默认密码策略 MD5         Security = new MD5(),        //被加密的 军*情*信*息        ClassifiedInfomation = @"+30/SxY2HZ0UtqUVNGMsad0zfajsHQmja1NVC+639zC6y0dE/8XDZJefMl0NwBJ+sUA8LC8k/IPEeTtFqW6OWaaZH9A+TNWzrJ6MSV2qiM3px6wFAyDkJsMKex0mJNe5",      };      //用 MD5 破解      string result_md5 = MI6.Encrypt();      Console.WriteLine("用MD5破解敌*人机密文件：" + result_md5);      Console.WriteLine("MD5加密后，还是一团乱麻，机密文件无法破解");      Console.WriteLine();      //用 RSA 破解      MI6.Security = new RSA();      string Result_RSA = MI6.Encrypt();      Console.WriteLine(Result_RSA);      //用 DES 破解      string symmetricKey = "AfricaArea";//007完成使命，拿到了密钥      MI6.Security = new DES { SymmetricKey = symmetricKey };      //解密后的内容应该是：军-情-机-密-信-息:我军将要攻打 非*洲，战区指挥官：隆美尔，坦克：500辆，飞机：2000架      Console.WriteLine();      Console.WriteLine("007获取到了DES解密密码，打开了 军-事-机-密文件，内容如下：" + MI6.Decrypt(MI6.ClassifiedInfomation));      Console.ReadKey();    }  }}

7.运行结果