bugcheck / TinyRSA

A 2048-bit RSA libary that is actually easy to implement

TinyRSA

An RSA libary that is actually easy to implement and use. After having great difficulty using OpenSSL... LibTomCrypt... various others... I decided to make my own instead, designed for simplicity and ease of use for the programmer. This libary does not include padding, ideal-prime-checking, or other advanced features for commercial applications, but should work well for smaller projects with limited audiences.

Current Features

• Generate keys
  • Generate a prime number
    • Generate a large number
    • Primality check (Miller-Rabin)
• Encrypt a number (given public key and n)
• Decrypt a number (given private key and n)

Upcoming Features

• Store keys/outputs as std::string so the user doesn't need to deal with GMP
• More header guards/standardized formatting
• More comments :-)
• Standalone compiling (without requiring GMP)

Requirements

TinyRSA uses the GNU Multiprecision (GMP) number library to store numbers -- this will need to be installed on the system

Example

#include <iostream>

#include "TinyRSA.h"
#include <gmpxx.h>

int main()
{
    TinyRSA rsa; // make a TinyRSA object to access its functions

    // keys, will be modifed by the generate_keys() function
    mpz_class public_key;
    mpz_class private_key;
    mpz_class n;
    
    rsa.generate_keys(public_key, private_key, n, 613); // generates the keys; 613 represents a 2048-bit encryption

    mpz_class testnum; // test number to encrypt
    testnum = "123"; // using 123 as an example

    mpz_class encrypted;
    encrypted = rsa.encrypt(testnum, public_key, n); // uses the public key and n to encrypt testnum

    std::cout << "Encrypted: " << encrypted << std::endl;

    mpz_class decrypted;
    decrypted = rsa.decrypt(encrypted, private_key, n); // uses the private key and n to decrypt the encrypted value

    std::cout << "Decrypted: " << decrypted << std::endl;
    return 0;
}