newSender method
Creates an HPKE sender context for multi-message encryption.
Returns the sender context and a 1120-byte encapsulated key that must be transmitted to the recipient for SecretKey.newReceiver.
Messages encrypted with the returned context must be decrypted in order by the corresponding receiver.
domain: Application-specific domain separator
Implementation
(Sender, Uint8List) newSender({required Uint8List domain}) {
final (sender, encapKey) = _inner.newSender(domain: domain);
return (Sender._(sender), encapKey);
}