C#設計模式之Strategy策略模式解決007大破密碼危機問題示例

更新時間：2017年09月13日 11:07:17 作者：GhostRider

這篇文章主要介紹了C#設計模式之Strategy策略模式解決007大破密碼危機問題,簡單描述了策略模式的定義并結合加密解密算法實例分析了C#策略模式的具體使用方法,需要的朋友可以參考下

本文實例講述了C#設計模式之Strategy策略模式解決007大破密碼危機問題。分享給大家供大家參考，具體如下：

一、理論定義

策略模式定義了多套算法，這些算法在客戶端可以任意切換。

二、應用舉例

需求描述：話說007在皇家賭場賭牌，突然接到M夫人的急電，要求立刻去非洲尋找一個DES對稱算法密鑰，以破解敵人的軍*情*機*密

1、(英*國*軍*情*六*局)MI6=Military Intelligence 6 截獲了一個非*洲戰(zhàn)*區(qū)軍*事*機*密文件，采用 MD5，RAS，加密，解密，都無法破解
后來發(fā)現(xiàn)，這文件被DES加密，必須找回對稱密鑰，才可以破解
2、邦德火速趕往非洲，目標只有一個：找到密鑰。

三、具體編碼

1.定義安全算法接口，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加密函數(shù)
    /// </summary>
    /// <param name="xmlPublicKey">說明:KEY必須是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 "敵人密碼太難破解，已經(jīng)超過了RSA算法的承受能力，要采取分段加密"; }
    }
    /// <summary>
    /// RSA解密函數(shù)
    /// </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 "敵人密碼太難破解，已經(jīng)超過了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 的摘要說明
/// </summary>
namespace Com.Design.Gof.Strategy
{
  public class DES:ISecurity
  {
    private static byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF }; //密鑰向量
    //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">加密密鑰</param>
    /// <returns>加密成功返回加密后的字符串,失敗返回源串</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,失敗返源串</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*國*軍*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*國*軍*情*六*局)MI6=Military Intelligence 6
  /// </summary>
  public class MilitaryIntelligence6
  {/// <summary>
    /// 安全策略
    /// </summary>
    private ISecurity Security { get; set; }
    /// <summary>
    /// 被加密的軍*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.主函數(shù)

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 設計模式測試項目是一起的，想測試誰，就調(diào)用誰
    /// </summary>
    /// <param name="args"></param>
    static void Main(string[] args)
    {
      MilitaryIntelligence6 MI6= new MilitaryIntelligence6
      {
        //默認密碼策略 MD5
         Security = new MD5(),
        //被加密的 軍*情*信*息
        ClassifiedInfomation = @"+30/SxY2HZ0UtqUVNGMsad0zfajsHQmja1NVC+639zC6y0dE/8XDZJefMl0NwBJ+sUA8LC8k/IPEeTtFqW6OWaaZH9A+TNWzrJ6MSV2qiM3px6wFAyDkJsMKex0mJNe5",
      };
      //用 MD5 破解
      string result_md5 = MI6.Encrypt();
      Console.WriteLine("用MD5破解敵*人機密文件：" + result_md5);
      Console.WriteLine("MD5加密后，還是一團亂麻，機密文件無法破解");
      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，拿到了密鑰
      MI6.Security = new DES { SymmetricKey = symmetricKey };
      //解密后的內(nèi)容應該是：軍-情-機-密-信-息:我軍將要攻打 非*洲，戰(zhàn)區(qū)指揮官：隆美爾，坦克：500輛，飛機：2000架
      Console.WriteLine();
      Console.WriteLine("007獲取到了DES解密密碼，打開了 軍-事-機-密文件，內(nèi)容如下：" + MI6.Decrypt(MI6.ClassifiedInfomation));
      Console.ReadKey();
    }
  }
}

7.運行結果