class Aws::S3::EncryptionV2::IOEncrypter

def encrypt_to_tempfile(cipher, io)
  encrypted = Tempfile.new(self.object_id.to_s)
  encrypted.binmode
  while chunk = io.read(ONE_MEGABYTE, read_buffer ||= String.new)
    if cipher.method(:update).arity == 1
      encrypted.write(cipher.update(chunk))
    else
      encrypted.write(cipher.update(chunk, cipher_buffer ||= String.new))
    end
  end
  encrypted.write(cipher.final)
  encrypted.write(cipher.auth_tag)
  encrypted.rewind
  encrypted
end