encrypt method
Implementation
@override
Future<String?> encrypt(String msg, String destPubKey, {String? id}) async {
final npub = publicKey.startsWith('npub')
? publicKey
: Nip19.encodePubKey(publicKey);
Map<dynamic, dynamic> map = await amberFlutterDS.amber.nip04Encrypt(
plaintext: msg, currentUser: npub, pubKey: destPubKey, id: id);
return map['signature'];
}