feat: NIP17

Author: ethicnology

README.md

@@ -22,6 +22,7 @@ flutter pub add nostr
 - [x] [NIP 10 Conventions for clients' use of e and p tags in text events](https://github.com/nostr-protocol/nips/blob/master/10.md)
 - [x] [NIP 13 Proof of Work](https://github.com/nostr-protocol/nips/blob/master/13.md)
 - [x] [NIP 15 End of Stored Events Notice](https://github.com/nostr-protocol/nips/blob/master/15.md)
+- [x] [NIP 17 Private Direct Messages (Partial)](https://github.com/nostr-protocol/nips/blob/master/17.md)
 - [x] [NIP 19 bech32-encoded entities](https://github.com/nostr-protocol/nips/blob/master/19.md)
 - [x] [NIP 20 Command Results](https://github.com/nostr-protocol/nips/blob/master/20.md)
 - [x] [NIP 21 nostr: URI scheme](https://github.com/nostr-protocol/nips/blob/master/21.md)

lib/nostr.dart

@@ -18,6 +18,7 @@ export 'src/nips/nip_005.dart';
 export 'src/nips/nip_009.dart';
 export 'src/nips/nip_010.dart';
 export 'src/nips/nip_013.dart';
+export 'src/nips/nip_017.dart';
 export 'src/nips/nip_019.dart';
 export 'src/nips/nip_020.dart';
 export 'src/nips/nip_021.dart';

lib/src/nips/nip_017.dart

@@ -0,0 +1,43 @@
+import 'package:nostr/nostr.dart';
+
+class Nip17 {
+  static Future<Event> encode({
+    required String message,
+    required String authorPrivkey,
+    required String receiverPubkey,
+  }) async {
+    final authorPubkey = Keychain(authorPrivkey).public;
+
+    final rumor = Event.partial(
+      pubkey: authorPubkey,
+      kind: 14,
+      content: message,
+    );
+    rumor.id = rumor.getEventId();
+    // Kind 14s MUST never be signed.
+    // If it is signed, the message might leak to relays and become fully public.
+    rumor.sig = '';
+
+    return await Nip59.wrap(
+      rumor: rumor,
+      authorPrivkey: authorPrivkey,
+      recipientPubkey: receiverPubkey,
+    );
+  }
+
+  static Future<Event> decode({
+    required Event giftWrap,
+    required String receiverPrivkey,
+  }) async {
+    final dm = await Nip59.unwrap(
+      giftWrap: giftWrap,
+      recipientPrivkey: receiverPrivkey,
+    );
+
+    if (dm.kind != 14) {
+      throw Exception('NIP-17 define private direct messages with kind=14');
+    }
+
+    return dm;
+  }
+}

test/nips/nip_017_test.dart

@@ -0,0 +1,46 @@
+import 'package:nostr/src/nips/nip_017.dart';
+import 'package:test/test.dart';
+import 'package:nostr/nostr.dart';
+
+void main() async {
+  final authorNsec =
+      'nsec1w8udu59ydjvedgs3yv5qccshcj8k05fh3l60k9x57asjrqdpa00qkmr89m';
+  final authorPrivkey = Nip19.decodePrivkey(authorNsec);
+  final author = Keychain(authorPrivkey);
+
+  final recipientNsec =
+      'nsec12ywtkplvyq5t6twdqwwygavp5lm4fhuang89c943nf2z92eez43szvn4dt';
+  final recipientPrivkey = Nip19.decodePrivkey(recipientNsec);
+  final recipient = Keychain(recipientPrivkey);
+
+  final message = 'Hola, que tal?';
+
+  final dm = await Nip17.encode(
+    authorPrivkey: author.private,
+    receiverPubkey: recipient.public,
+    message: message,
+  );
+
+  group('NIP-17 Direct Message', () {
+    test('encode a direct message', () async {
+      expect(dm.kind, 1059);
+      expect(dm.tags, [
+        [
+          "p",
+          "918e2da906df4ccd12c8ac672d8335add131a4cf9d27ce42b3bb3625755f0788"
+        ]
+      ]);
+    });
+
+    test('decode a direct message', () async {
+      final x = await Nip17.decode(
+        giftWrap: dm,
+        receiverPrivkey: recipient.private,
+      );
+
+      expect(x.kind, 14);
+      expect(x.pubkey, author.public);
+      expect(x.sig, isEmpty);
+    });
+  });
+}