Nip44Encrypt

lib/src/nostr_signer_actor.dart

@@ -1,6 +1,7 @@
 import 'package:actors/actors.dart';
 import 'package:bip340/bip340.dart' as bip340;
 
+import 'nip44.dart';
 import 'nostr_event.dart';
 
 sealed class SignerMessage {
@@ -24,6 +25,20 @@ final class GetPublicKey extends SignerMessage {
   const GetPublicKey();
 }
 
+/// NIP-44 v2 encrypt-to-self: encrypts [plaintext] with this signer's own key
+/// (conversation key derived from its private key and public key).
+final class Nip44Encrypt extends SignerMessage {
+  final String plaintext;
+  const Nip44Encrypt(this.plaintext);
+}
+
+/// NIP-44 v2 decrypt-from-self: inverse of [Nip44Encrypt]. Throws on a version
+/// mismatch or HMAC failure (e.g. a payload sealed with a different key).
+final class Nip44Decrypt extends SignerMessage {
+  final String payload;
+  const Nip44Decrypt(this.payload);
+}
+
 sealed class SignerResult {
   const SignerResult();
 }
@@ -38,6 +53,12 @@ final class PublicKeyResult extends SignerResult {
   const PublicKeyResult(this.publicKey);
 }
 
+/// Result of a [Nip44Encrypt] (base64 payload) or [Nip44Decrypt] (plaintext).
+final class Nip44Text extends SignerResult {
+  final String value;
+  const Nip44Text(this.value);
+}
+
 class NostrSignerActor with Handler<SignerMessage, SignerResult> {
   final String _privateKey;
   final String _publicKey;
@@ -51,6 +72,12 @@ class NostrSignerActor with Handler<SignerMessage, SignerResult> {
         SignEvent(:final kind, :final tags, :final content, :final createdAt) =>
           Future.value(_signEvent(kind, tags, content, createdAt)),
         GetPublicKey() => Future.value(PublicKeyResult(_publicKey)),
+        Nip44Encrypt(:final plaintext) => Future.value(
+            Nip44Text(nip44Encrypt(plaintext, _privateKey, _publicKey)),
+          ),
+        Nip44Decrypt(:final payload) => Future.value(
+            Nip44Text(nip44Decrypt(payload, _privateKey, _publicKey)),
+          ),
       };
 
   EventSigned _signEvent(