Public-key encryption with Ruby.

rsa_decrypt.rb

require 'openssl'
require 'base64'

ciphertext  = Base64.decode64("CIPHERTEXT GOES HERE")
passphrase  = ENV['PRIVATE_KEY_PASSPHRASE'] # read in from environment
private_key = OpenSSL::PKey::RSA.new(File.read('path/to/private_key.pem'), passphrase)
plaintext   = private_key.private_decrypt(ciphertext, OpenSSL::PKey::RSA::PKCS1_PADDING)

puts "Plain text is: " + plaintext

rsa_encrypt.rb

require 'openssl'
require 'base64'

public_key = OpenSSL::PKey::RSA.new(File.read('path/to/public_key.pem'), '')
ciphertext = public_key.public_encrypt(plaintext, OpenSSL::PKey::RSA::PKCS1_PADDING)
ciphertext = Base64.encode64(ciphertext)

puts "Encrypted text is: " + ciphertext