C++ file hash changer for macOS

main.cpp

#include <iostream>
#include <fstream>
#include <sys/stat.h>

using namespace std;

void gen_random(char *s, const int len) {
    srand(static_cast<unsigned int>(time(NULL) * time(NULL)));
    static const char letters[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    
    for (int i = 0; i < len; ++i) {
        s[i] = letters[rand() % (sizeof(letters) - 1)];
    }
    
    s[len] = 0;
}

int main(int argc, const char * argv[]) {
    char *new_name = new char[5];
    char *extra_byte = new char[5];
    gen_random(new_name, 5);
    gen_random(extra_byte, 1);

    ifstream src(argv[0], ios::binary);
    ofstream dst(new_name, ios::binary);
    chmod(new_name, S_IRWXU);
    
    dst << src.rdbuf();
    dst << extra_byte;
    
    dst.close();
    src.close();
    
    remove(argv[0]);
    
    cout << "Hello, World!\n";
    return 0;
}