Ruby AES Cryptography

cryptomancer.rb

require 'openssl'
require 'stringio'
require 'base64'

class Cryptomancer
  def initialize(alg: nil, key: nil)
    @alg = alg || "AES-256-CBC"
    @key = key || "1234567890123456ASDFasdfASDFasdf"  # 32 byte key for 256-bit AES (16 bytes for 128-bit...)
  end

  def encrypt(str)
    aes = OpenSSL::Cipher.new(@alg)
    aes.encrypt
    aes.key = @key
    aes.random_iv
    enc = ""
    f = StringIO.new(str)
    loop do
      r = f.read(4096)
      break unless r
      cipher = aes.update(r)
      enc += cipher
    end
    enc += aes.final
    return Base64.encode64(enc)
  end

  def decrypt(data)
    bytes = Base64.decode64(data)
    aes = OpenSSL::Cipher.new(@alg)
    aes.decrypt
    aes.key = @key
    aes.update(bytes)
  end
end