instance method encrypt

# File activesupport/lib/active_support/message_encryptor.rb, line 277
      def encrypt(data)
        cipher = new_cipher
        cipher.encrypt
        cipher.key = @secret

        # Rely on OpenSSL for the initialization vector
        iv = cipher.random_iv
        cipher.auth_data = "" if aead_mode?

        encrypted_data = cipher.update(data)
        encrypted_data << cipher.final

        parts = [encrypted_data, iv]
        parts << cipher.auth_tag(AUTH_TAG_LENGTH) if aead_mode?

        join_parts(parts)
      end