Random 32 hex-character string

generate_random_key.cpp

#include <iostream>
#include <chrono>
#include <fstream>
#include <array>
#include <random>
#include <cstddef>

void key_gen(std::ofstream& fout);

int main() {
    std::string key_file_name {"key.txt"};
    std::ofstream file{key_file_name};
    
    if (!file) {
        std::cerr << "Cannot open file <" << key_file_name << ">" << std::endl;
        
        return 1;
    }
	
    key_gen(file);
    std::cout << "Key is generated" << std::endl;
    
    return 0;
}

void key_gen(std::ofstream& fout) {
    std::random_device rd;
    std::mt19937 gen(rd());
    auto curr_clock = std::chrono::high_resolution_clock::now();
    std::seed_seq sseq {
        std::chrono::duration_cast<std::chrono::hours> (curr_clock.time_since_epoch()).count(), 
        std::chrono::duration_cast<std::chrono::seconds> (curr_clock.time_since_epoch()).count()
        };
    
    gen.seed(sseq);
    // generator for hex numbers from 0 to F
    std::uniform_int_distribution<int> dis(0x0, 0xF);
    constexpr int key_size = 32;
    
    fout << std::hex;
    for (std::size_t i = 0; i < key_size; ++i) {
	fout << dis(gen);
    }
}