//Virginia密码
/*理解算法最重要，最好自己动手实现试试看，可以使用MFC写一个简单的交互界面*/
#include<iostream> 
#include<cstring> 

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; 
}