RSA encryption/decryption

rsa_enc_dec.rb

require 'base64'
require 'openssl'

def enc(der, msg)
  rsa = OpenSSL::PKey::RSA.new(der)
  rsa.private_encrypt(msg)
end

def dec(der, msg)
  rsa = OpenSSL::PKey::RSA.new(der)
  rsa.public_decrypt(msg)
end

OpenSSL::Random.seed(File.read("/dev/random", 16))

msg = 'hello world'

puts '## original'
puts msg

rsa = OpenSSL::PKey::RSA.generate(2048) # initialize                                                                                                          
der =  Base64.strict_encode64(rsa.to_der) # store this in DB                                                                                                  

puts '## public key'
puts rsa.public_key

puts '## public key (base64 encoded)'
puts Base64.strict_encode64(rsa.public_key.to_text)

decoded_der = Base64.strict_decode64(der)
enc_msg = Base64.strict_encode64(enc(decoded_der, msg))

puts '## encrypted'
puts enc_msg

decrypted = dec(decoded_der, Base64.strict_decode64(enc_msg))

puts '## decrypted'
puts decrypted