一個加密算法 -- 每次生成不重複的密文

一個加密算法

聽說此加密算法每次加密的結果都不一樣，但解密的結果相同

using System;

namespace test001
{
 /**
   對sSource，進行加密、解密操做。
   @param sSource String ：操做的字符串
   @param iFlag int :操做類型 1-加密  2-解密
   @return String :加密或解密後的字符串
    **/
 public class password
 {
  public password()
  {
  }
  public static string pWord(string sSource,int iFlag)
  {
   if(sSource==null)
    return null;
   if(sSource.Equals(""))
    return "";
   int li_len,i,li_asc,li_rand,li_head;
            string ls_i,ls_code="";
   if(iFlag ==1)
   {
    li_len=sSource.Length;
    Random rdm1 = new Random(~unchecked((int)DateTime.Now.Ticks)); 
    li_head=(int)(rdm1.NextDouble()*10);
    if(li_head ==0)
     li_head =1;
    for(i=0; i<li_len; i++)
    {
     Random rdm2 = new Random(~unchecked((int)DateTime.Now.Ticks)); 
     int rand2 =(int)(rdm2.NextDouble() *94);
     if(rand2 ==0)
      rand2 =1;
     li_rand=rand2+32;
     li_asc=Convert.ToInt32(sSource.ToCharArray(i,1)[0]);
     ls_i=((char)(li_asc -i)).ToString();

     if(li_asc+i+li_head>126)
     {
      if(li_rand%2 ==1)
       li_rand=li_rand+1;
      ls_i=((char)(li_rand)).ToString()+((char)(li_asc -i -li_head)).ToString();
     }
     else
     {
      if(li_rand%2 ==0) 
       li_rand=li_rand+1;
      ls_i=((char)(li_rand)).ToString()+((char)(li_asc +i +li_head)).ToString();
     }
     ls_code=ls_code+ls_i;
    }
    Random rdm3 = new Random(~unchecked((int)DateTime.Now.Ticks)); 
    int rand1 =(int)(rdm3.NextDouble()*9);
    if(rand1 ==0)
     rand1 =1;
    ls_code=((char)(rand1*10+li_head+40)).ToString()+ls_code;
   }
   else
   {
    int li_ret;
    li_len=sSource.Length;
    ls_code="";
    li_ret=Convert.ToInt32(sSource.ToCharArray(0,1)[0]) %10;
    for( i=2;i <li_len; i=i+2)
    {
     li_asc=Convert.ToInt32(sSource.ToCharArray(i,1)[0]);
     if(Convert.ToInt32(sSource.ToCharArray(i - 1,1)[0]) %2 ==0)
     {
      ls_i=((char)(li_asc + (i - 1)/2 + li_ret)).ToString();
     }
     else
     {
      ls_i=((char)(li_asc - (i - 1)/2 - li_ret)).ToString();
     }
     ls_code=ls_code+ls_i;
    }
   }
   return ls_code;
  }
 }
}

 

出處：http://www.cnblogs.com/tuyile006/archive/2006/07/19/454867.html

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我根據上面的代碼作了註釋的形式，以下代碼：

        /// <summary>
        /// 對sSource，進行加密、解密操做。
        /// </summary>
        /// <param name="sSource">須要加密或解密的字符串</param>
        /// <param name="iFlag">操做類型 1-加密  2-解密</param>
        /// <returns>加密或解密後的字符串</returns>
        public static string pWord(string sSource, int iFlag)
        {
            if (sSource == null)
                return null;
            if (sSource.Equals(""))
                return "";
            int li_len, i, li_asc, li_rand, li_head;
            string ls_i, ls_code = "";
            if (iFlag == 1)//加密操做
            {
                li_len = sSource.Length;
                Random rdm1 = new Random(~unchecked((int)DateTime.Now.Ticks));
                li_head = (int)(rdm1.NextDouble() * 10);//產生0-9的隨機數
                if (li_head == 0)
                    li_head = 1;
                for (i = 0; i < li_len; i++)
                {
                    //ASCII可顯示字符是從32-126，因此從新構建一個這個之間的數

                    Random rdm2 = new Random(~unchecked((int)DateTime.Now.Ticks));//能夠嘗試: Random rdm2 = new Random(~unchecked(rdm1.Next()));
                    int rand2 = (int)(rdm2.NextDouble() * 94);//產生0-93之間的隨機數，
                    if (rand2 == 0)
                        rand2 = 1;
                    li_rand = rand2 + 32;//這個數就是32-126之間的數
                    li_asc = Convert.ToInt32(sSource.ToCharArray(i, 1)[0]);
                    ls_i = ((char)(li_asc - i)).ToString();

                    if (li_asc + i + li_head > 126)
                    {
                        if (li_rand % 2 == 1)
                            li_rand = li_rand + 1;//設置爲偶數
                        ls_i = ((char)(li_rand)).ToString() + ((char)(li_asc - i - li_head)).ToString();//加密算法生成兩個字符，第一關字符是隨機生成的偶數可顯示ASCII字符，第二個是真正的字符
                    }
                    else
                    {
                        if (li_rand % 2 == 0)
                            li_rand = li_rand + 1;//設置爲奇數
                        ls_i = ((char)(li_rand)).ToString() + ((char)(li_asc + i + li_head)).ToString();//加密算法生成兩個字符，第一關字符是隨機生成的奇數可顯示ASCII字符，第二個是真正的字符
                    }
                    ls_code = ls_code + ls_i;
                }
                Random rdm3 = new Random(~unchecked((int)DateTime.Now.Ticks));
                int rand1 = (int)(rdm3.NextDouble() * 9);
                if (rand1 == 0)
                    rand1 = 1;
                ls_code = ((char)(rand1 * 10 + li_head + 40)).ToString() + ls_code;//每次參與運算的li_head通過加密後放到密文的第一個字符，而且是可顯字符
            }
            else //解密操做
            {
                int li_ret;
                li_len = sSource.Length;
                ls_code = "";
                li_ret = Convert.ToInt32(sSource.ToCharArray(0, 1)[0]) % 10;
                for (i = 2; i < li_len; i = i + 2)
                {
                    li_asc = Convert.ToInt32(sSource.ToCharArray(i, 1)[0]);//獲取參與解密的數字
                    if (Convert.ToInt32(sSource.ToCharArray(i - 1, 1)[0]) % 2 == 0)//判斷偶數或奇數解密算法
                    {
                        ls_i = ((char)(li_asc + (i - 1) / 2 + li_ret)).ToString();//由於sSource中的第一位保存了密鑰，從第三位開始全部奇數位纔是真正須要解密的數據
                    }
                    else
                    {
                        ls_i = ((char)(li_asc - (i - 1) / 2 - li_ret)).ToString();
                    }
                    ls_code = ls_code + ls_i;
                }
            }
            return ls_code;
        }
    

上面的就不用我說明了，註釋都寫清楚了，只是加密後的密文要比明文多一倍+1個字符