维吉尼亚（Vigenere）密码为了提高密码的破译的难度

// 实验：维吉尼亚密码算法
// 姓名： 
// 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;
}