This is a C++20 project

The RSA implementation contains a few components

• SHA512 hash function
• Pseudo random number generator (uses SHA512)
• Prime number generator (uses boost::multiprecision::miller_rabin_test)
• RSA public-private key pair generator

using namespace cryptb

e is always 65537 and d is always positive. Couldn't be simpler!
This library aspires to keep only the bare minimum for a fully functioning secure general purpose cryptosystem.
In the future we will support symmetric encryption and older versions of C++.

Pitfalls

Since this is vanilla RSA with no fancy padding etc. there are only two ways to use this library securely.

• Choose a random number in the range [0, N) and encrypt it using cryptb::rsa::encrypt.
• Take the SHA512 hash of some unique binary information (such as a PDF file) and convert that into a number, and then sign it using cryptb::rsa::sign
  
  Don't
• Use RSA for anything but key exchange and digital signatures.
• Sign a message directly (always use the hash).
• Encrypt a short/unsecure number (with less than 512 bits).

rsa_cpp

Simple RSA Implementation
Uses boost::endian and boost::multiprecision::cpp_int and C++20 features.

Simplicity Is The First Step To Security

It doesn't have to be complicated.
A human is more likely to be compromized than a 1024 bit prime number. That's a fact.