def encrypt!
      bin_sk = fix_private_key(@private_key).scan(/../).map(&:hex).reverse.pack('C*')
      bin_pk = (public_key || @public_key).scan(/../).map(&:hex).pack('C*')
      @value = Nis::Util::Ed25519.encrypt(bin_sk, bin_pk, value)
      @type = TYPE_ENCRYPTED