👀 Views: 69 💬 Answers: 1 📅 Created: 2025-09-06

C++ security randomness OpenSSL API

I'm trying to implement I've been banging my head against this for hours. I've been banging my head against this for hours. Building an application that requires secure API authentication has led me to explore token generation techniques in C++. While researching, I came across various methods to generate random tokens using the standard library. However, I’m unsure about the best practices for ensuring the randomness and security of these tokens. I initially tried using `std::random_device` to seed a `std::mt19937` generator, but I’m concerned about potential predictability. Here’s the code I implemented: ```cpp #include <random> #include <string> #include <iostream> std::string generate_token(size_t length) { std::random_device rd; std::mt19937 gen(rd()); std::uniform_int_distribution<> dis(0, 255); std::string token; for (size_t i = 0; i < length; ++i) { token += static_cast<char>(dis(gen)); } return token; } int main() { std::string token = generate_token(32); std::cout << "Generated Token: " << token << std::endl; return 0; } ``` The output seems okay, but I worry about the strength of the randomness. I've read that using `std::random_device` might not be secure on all platforms. For comparison, I also experimented with OpenSSL’s RAND_bytes function: ```cpp #include <openssl/rand.h> #include <iostream> #include <string> std::string generate_secure_token(size_t length) { unsigned char buffer[length]; if (RAND_bytes(buffer, length) != 1) { throw std::runtime_error("Error generating secure random bytes"); } return std::string(reinterpret_cast<char*>(buffer), length); } int main() { try { std::string token = generate_secure_token(32); std::cout << "Secure Token: " << token << std::endl; } catch (const std::runtime_error& e) { std::cerr << e.what() << std::endl; } return 0; } ``` This approach seems more robust, but it adds an external dependency. Can anyone share insights on whether it's better to stick with the standard library or leverage OpenSSL for secure token generation? Additionally, are there any potential pitfalls with using OpenSSL in terms of configuration or performance for a full-stack application? Your experience and advice would be greatly appreciated. For context: I'm using C++ on Ubuntu. Is there a better approach? This is part of a larger service I'm building. Am I missing something obvious? I'm using C++ latest in this project. What's the correct way to implement this?