Just use ruby rabin_encryption.rb to get started.
You can see usage with ruby rabin_signing.rb.
To see how it behaves on corrupted or modified files, you can use corrupter.rb to corrupt your dummy file and try to verify. Usage same as rabin_encryption.rb.
PS: Beware, corrupter.rb has issues with Ruby version 2.2
This project uses Ruby's OpenSSL,Digest, Prime and SecureRandom libraries.
Only tested on Linux(Arch Linux and Solus Linux) Ruby Version 2.4.1.