aes_crypto.rb

  class AESCrypto
    # @!attribute cipher
    #   @return [OpenSSL::Cipher] the cipher object used to encrypt and decrypt
    # @!attribute iv
    #   @return [String] the initialization vector used for the cipher object
    # @!attribute key
    #   @return [String] the key used for the cipher object
    
    require 'openssl'
    require 'base64'

    def initialize(iv = '', key = '', length = '128', mode = :CBC)
      @cipher = OpenSSL::Cipher::AES.new(length, mode)
      @iv = iv != '' ? iv : @cipher.random_iv
      @key = key != '' ? hex_to_bin(key) : hex_to_bin(@cipher.random_key)
    end

    # @param data [String] the data to be encrypt
    # @return [Base64 String] the string in base64 encrypted
    def encrypt(data)
      @cipher.encrypt
      @cipher.iv = @iv
      @cipher.key = @key
      Base64.encode64(@iv + @cipher.update(data) + @cipher.final)
    end

    # @param data [Base64 String] the string in base64 that will be decrypt
    # @return [String] the string decrypted
    def decrypt(data)
      data = Base64.decode64(data)
      @iv = data[0...16]
      data = data[16...data.length]
      @cipher.decrypt
      @cipher.iv = @iv
      @cipher.key = @key
      @cipher.update(data) + @cipher.final
    end

    private

    # @param s [String] the data to be converted to binary
    # @return [String] the data converted to binary
    def hex_to_bin(s)
      s.scan(/../).map { |x| x.hex.chr }.join
    end

  end

end