乘数加密解密

最新推荐文章于 2021-03-04 20:36:01 发布

转载最新推荐文章于 2021-03-04 20:36:01 发布 · 457 阅读

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原文链接：https://my.oschina.net/u/1240964/blog/170904

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#c/c++ #python

2019独角兽企业重金招聘Python工程师标准>>>

//功能：乘数加密 K=3 5 7 9 11 15 17 19 21 23 25

#include <stdio.h>
int str_len(char *str)//求字符串的长度
{
int len = 0;
while(*(str++))
  len++;
return len;
}
int main(int argc, char *argv[])
{
char a[26] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
char b[26] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
char str[50];
int k;
printf("Please input the words（必须是小写可以用函数改变） :");
gets(str);
printf("Please input the following number[3][5][9][11][15][17][19][21][23]:");//可以求逆元的数
  scanf("%d",&k);
int len = str_len(str);
for(int i = 0;i<len;i++)
  for(int j = 0;j<26;j++)
  {
   if(str[i]==a[j])
    str[i] = b[(k*j)%26]//换
   else
    str[i] = str[i];//将空格等符号落下来
   }
  printf("%s\n",str);//打印
return 0;
}

//解密

#include <stdio.h>

求字符串长度
int str_len(char *str)
{
int len = 0;
while(*(str++))
len++;
return len;
}

//求逆元
int mulny(int k)
{
int t;
for(int i = 0;i<26;i++)
{
  t=k*i;
  if(t%26==1)
   return i;
}
}

int main(int argc, char *argv[])
{
char a[26] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
char b[26] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
char str[50];
int k;
printf("Please input the words :");
gets(str);
printf("Please input the following number[3][5][9][11][15][17][19][21][23]:");//26以内有逆元的数字
scanf("%d",&k);
int p = mulny(k);
int len = str_len(str);
for(int i = 0;i<len;i++)
  for(int j = 0;j<26;j++)
  {
   if(str[i]==a[j])
    str[i] = b[(p*j)%26];
   else
    str[i] = str[i];
  }
  printf("%s\n",str);
return 0;
}