密码学实验之凯撒密码和维吉尼亚密码的加解密

1.凯撒密码的加解密
源代码：
#include<stdafx.h>
#include <stdio.h>
#include <string.h>
int main()
{
char s[100],c;
int i,p,d,e;
printf("请选择: A.加密B.解密Q.退出\n"); scanf("%c",&c);
if(c=='a'||c=='A')
{
printf("输入明文:");
scanf("%s",&s);
p=strlen(s);
printf("请设置偏移量:");
scanf("%d",&d);
for(i=0;i<p;i++)
{
if(s[i]>='a' && s[i]<='z')
s[i]=(s[i]-'a'+d)%26+'a';
else if(s[i]>='A' && s[i]<='Z')
s[i]=(s[i]-'A'+d)%26+'A';
else s[i]=s[i]+d;
}
printf("%s",s);
printf("\n\n\n");
}
if(c=='b'||c=='B')
{
printf("请输入密文:");
scanf("%s",&s);
p=strlen(s);
printf("请输入加密的偏移变量:");
scanf("%d",&d);
for(i=0;i<p;i++)
{
if(s[i]>='a' && s[i]<='z')
{
e=s[i]-'a'-d;
if(e<=0)
s[i]=(e+26)%26+'a';
else s[i]=e%26+'a';
}
else if(s[i]>='A' && s[i]<='Z')
{
e=s[i]-'A'-d;
if(e<0)
s[i]=(e+26)%26+'A';
else s[i]=e%26+'A';
}
else s[i]=s[i]-d;
}
printf("%s",s);
printf("\n\n");
}
if(c=='q'||c=='Q')
return 0;
return 0;
}
运行结果是：
2.维吉尼亚密码的加解密
源代码：
#include "stdafx.h"
#include<iostream>
using namespace std;
#define MINCHAR 32
#define CHARSUM 94
char table[CHARSUM][CHARSUM];
bool Init();
bool Encode(char* key, char* source, char* dest);
bool Dncode(char* key, char* source, char* dest);
int main()
{
if(!Init())
{
cout << "初始化错误！" << endl;
return 1;
}
char key[256];
char str1[256];
char str2[256];
int operation;
while(1)
{
do
{
cout << "请选择一个操作：1. 加密；2. 解密；-1. 退出\n"; cin >> operation;
}while(operation != -1 && operation != 1 && operation != 2);
if(operation == -1)
return 0;
else if(operation == 1)//加密
{
cout << "请输入密钥：";
cin >> key;
cout << "请输入待加密字符串：";
cin >> str1;
Encode(key, str1, str2);
cout << "加密后的字符串：" << str2 << endl;
}
else if(operation == 2)//解密
{
cout << "请输入密钥：";
cin >> key;
cout << "请输入待解密字符串：";
cin >> str1;
Dncode(key, str1, str2);
cout << "解密后的字符串：" << str2 << endl;
}
cout << endl;
}
return 0;
}
// 初始化维吉尼亚方阵
bool Init()
{
int i, j;
for(i = 0; i < CHARSUM; i++)
{
for(j = 0; j < CHARSUM; j++)
{
table[i][j] = MINCHAR + (i + j) % CHARSUM;
}
}
return true;
}
// 加密
// key：密钥
// source：待加密的字符串
// dest：经过加密后的字符串
bool Encode(char* key, char* source, char* dest)
{
char* tempSource = source;
char* tempKey = key;
char* tempDest = dest;
do
{
*tempDest = table[(*tempKey) - MINCHAR][(*tempSource) - MINCHAR]; tempDest++;
if(!(*(++tempKey)))
tempKey = key;
}while(*tempSource++);
dest[strlen(source)] = 0;
return true;
}
// 解密
// key：密钥
// source：待解密的字符串
// dest：经过解密后的字符串
bool Dncode(char* key, char* source, char* dest)
{
char* tempSource = source;
char* tempKey = key;
char* tempDest = dest;
char offset;
do
{
offset = (*tempSource) - (*tempKey);
offset = offset >= 0 ? offset : offset + CHARSUM; *tempDest = MINCHAR + offset;
tempDest++;
if(!(*(++tempKey)))
tempKey = key;
}while(*++tempSource);
dest[strlen(source)] = 0;
return true;
}
运行结果如下：。