Шифрация

#include <iostream>
#include <ctime>
using namespace std;
 
std::string encrypt( std::string str, const char key );
std::string decrypt( std::string str, const char key );
int getRandomNum( const int min, const int max );
 
std::string encrypt( std::string str, const char key )
{
    const int size = str.size();
 
    char* buff = new char[size + 1];
    buff[size] = '\0';
    strcpy_s( buff, size +1 , str.c_str() );
    for(int i = 0; i < size; ++i)
    {
        char temp = buff[i];
        buff[i] = temp ^ key;
    }
    
    str = buff;
    delete buff;
    return str;
}
std::string decrypt( std::string str, const char key )
{
    const int size = str.size();
 
    char* buff = new char[size + 1];
    buff[size] = '\0';
    strcpy_s( buff, size + 1, str.c_str( ) );
    for(int i = 0; i < size; ++i)
    {
        char temp = buff[i];
        buff[i] = temp ^ key;
    }
    
    str = buff;
    delete buff;
    return str;
}
int getRandomNum( const int min, const int max )
{
    return min + rand() % (max - min);
}
int main()
{
    srand( time( NULL ) );
 
    char key = getRandomNum( 127, 255 );
    std::string data( "privet kak dela" );
 
    cout << data.c_str () << endl;
    data = encrypt( data, key );
    cout << data.c_str( ) << endl;
    data = decrypt( data, key );
    cout << data.c_str( ) << endl;
}