vigenere.cpp

Vigenere加密解密

#include <iostream.h>
using namespace std;
#define MINCHAR 33
#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<<"Initialize error!"<< endl;
      return 1;
  }
  char key[256];
  char str1[256];
  char str2[256];
  int coption;
  while(1)
  {
      do
      {
        cout << "Please select an option\n1 = Encryption\n2 = Decryption\n0 = Exit\n\nOption : ";
        cin >> coption;
      }while(coption != -1 && coption != 1 && coption != 2);
      if(coption == 0)
        exit(0);
      else if(coption == 1) //Encryption
      {
        cout << "\nEnter key : ";
        cin >> key;
        cout << "String to encrypt (without spacing) : ";
        cin >> str1;
        Encode(key, str1, str2);
        cout << "String after encrypt : " << str2 << endl;
      }
      else if(coption == 2) //Decryption
      {
        cout << "\nEnter key ：";
        cin >> key;
        cout << "String to decrypt (without spacing): ";
        cin >> str1;
        Dncode(key, str1, str2);
        cout << "String after decrypt : " << str2 << endl;
      }
      cout << endl;
  }
  return 0;
}

//Initialize Vigenere array
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;
}



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;
}



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;
}