변형 시저

#include <iostream>
#include <string.h>
#include <cstdlib>
#include <ctime>
using namespace std;

typedef int KEY;
typedef string CIPHER_TEXT;

class CEASAR{
public:
    string plaintext;
    string ciphertext;
    int secretKey_upper;
    int secretKey_lower;
public:
    CEASAR();   //[1]
    void INPUT_PLAINTEXT(); //[2]
    KEY SECRET_CEASAR_KEY_UPPER();    //[3]
    KEY SECRET_CEASAR_KEY_LOWER();    //[4]
    CIPHER_TEXT ENCRYPT_CEASAR(string, int, int);   //[5]

};
CEASAR::CEASAR() {  //[1]
    this->plaintext = " ";
    this->ciphertext = " ";
    this->secretKey_upper = 0;
    this->secretKey_lower = 0;
}
void CEASAR::INPUT_PLAINTEXT() {    //[2]
    cout << " [1] plaint text is ";
    getline(cin, this->plaintext);
}
KEY CEASAR::SECRET_CEASAR_KEY_UPPER() {   //[3]
    cout << " [2] secret_key_upper_return "<<endl;
    int temp_key = 0;
    temp_key = rand()%25 + 1; // key range: 1,2,3,4,5,...,25
    return temp_key;
}
KEY CEASAR::SECRET_CEASAR_KEY_LOWER() {   //[4]
    cout << " [3] secret_key_lower_return "<<endl;
    int temp_key = 0;
    temp_key = rand()%25 + 1; // key range: 1,2,3,4,5,...,25
    return temp_key;
}
CIPHER_TEXT CEASAR::ENCRYPT_CEASAR(string plaintext, int secret_key_u, int secret_key_l) {  //[5]
    cout << " [4] ciphter text is ";
    CIPHER_TEXT temp_cipher_text=" ";
    int increase_upper = 1;
    int increase_lower = 1;

    for(int index = 0; index<plaintext.length(); index++){
        if (isupper(plaintext[index])) {
            // case1: A, B, C, D, E, ..., Z
            temp_cipher_text += ((((plaintext[index] - 65) + secret_key_u + increase_upper) % 26) + 65);
            increase_upper++;
        }
        else if (islower(plaintext[index])) {
            // case2: a, b, c, d, e, ..., z
            temp_cipher_text += ((((plaintext[index] - 97) + secret_key_l + increase_lower) % 26) + 97);
            increase_lower++;
        }
        else {
            // case3:
            temp_cipher_text += plaintext[index];
        }
    }
    return temp_cipher_text;
}
int main(void)
{
    srand((unsigned int)time(NULL));
    cout<<"---------------------------------------"<<endl;
    cout<<"a b c d e ... z"<<endl;
    cout<<"int('a') is "<<int('a')<<endl;
    cout<<"..."<<endl;
    cout<<"int('z') is "<<int('z')<<endl;
    cout<<"---------------------------------------"<<endl;
    cout<<"A B C D E ... Z"<<endl;
    cout<<"int('A') is "<<int('A')<<endl;
    cout<<"..."<<endl;
    cout<<"int('Z') is "<<int('Z')<<endl;
    cout<<"---------------------------------------"<<endl;
    CEASAR cea;

    //[1] plainText
    cea.INPUT_PLAINTEXT();
    cout << "plaintext is "<<"[ "<<cea.plaintext<<" ]"<<endl;

    //[2] secretKey
    cea.secretKey_upper = cea.SECRET_CEASAR_KEY_UPPER();
    cout << "secretKey_upper is "<<"[ "<<cea.secretKey_upper<<" ]"<<endl;
    cea.secretKey_lower = cea.SECRET_CEASAR_KEY_LOWER();
    cout << "secretKey_lower is "<<"[ "<<cea.secretKey_lower<<" ]"<<endl;

    //[3] cipherText
    cea.ciphertext = cea.ENCRYPT_CEASAR(cea.plaintext, cea.secretKey_upper, cea.secretKey_lower);
    cout <<"[ "<<cea.ciphertext<<" ]"<<endl;
    return 0;
}