How can I fix the program so that the original message is equal to the decrypted one?

Question

Cryptography

#include <iostream>
#include <stdio.h>
#include <string>
#include <cstring>
using namespace std;

int main() {
  setlocale(LC_ALL, "rus");
  char msg[] = "Привет мир!";
  unsigned char key = 84;
  
  int N = strlen(msg);
  cout << N << endl;
  
  
  for (int i = 0; i < N; ++i) {
  
    msg[i] ^= key;
    msg[i] = ((msg[i] >> 2) | (msg[i] << 6));
}

  

  for (int i = 0; i < N; ++i) cout << msg[i];
  cout << endl;

  
  for (int i = 0; i < N; ++i) {
    msg[i] = ((msg[i] >> 6) | (msg[i] << 2));
    msg[i] ^= key;
}


  for (int i = 0; i < N; ++i) cout << msg[i];
  cout << endl;	
  
  
  return 0;
}

Answer 1

Convert character to unsigned char before shifting. The left shift of a signed variable is undefined behavior.