require 'rbnacl/libsodium'

require 'cryptor/symmetric_encryption/cipher'

module Cryptor
  class SymmetricEncryption
    module Ciphers
      # XSalsa20+Poly1305 authenticated stream cipher
      class XSalsa20Poly1305 < Cipher
        register :xsalsa20poly1305, key_bytes: RbNaCl::SecretBoxes::XSalsa20Poly1305.key_bytes

        def encrypt(key, plaintext)
          box(key).encrypt(plaintext)
        end

        def decrypt(key, ciphertext)
          box(key).decrypt(ciphertext)
        rescue RbNaCl::CryptoError => ex
          raise CorruptedMessageError, ex.to_s
        end

        private

        def box(key)
          RbNaCl::SimpleBox.new(RbNaCl::SecretBoxes::XSalsa20Poly1305.new(key))
        end
      end
    end
  end
end