// 实验：维吉尼亚密码算法
// 姓名： JJCCX
// 学号：
//
#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;
}
