feat: add converts for pub key

lib/src/utils.dart

@@ -1,6 +1,8 @@
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:convert/convert.dart';
+import 'package:dart_bech32/dart_bech32.dart';
 
 /// generates 32 random bytes converted in hex
 String generate64RandomHexChars() {
@@ -13,3 +15,34 @@ String generate64RandomHexChars() {
 int currentUnixTimestampSeconds() {
  return DateTime.now().millisecondsSinceEpoch ~/ 1000;
 }
+
+/// takes an npub key and converts it to hex key
+String? npubKeyToHex(String npub) {
+ try {
+ final decoded = bech32.decode(npub);
+ if (decoded.prefix == 'npub') {
+ final bytes = bech32.fromWords(decoded.words).sublist(0, 32);
+ final pubkey = hex.encode(bytes);
+ return pubkey;
+ }
+ return null;
+ } catch (e) {
+ return null;
+ }
+}
+
+/// takes an hex key and converts it to npub key
+String? hexKeyToNub(String hexkey) {
+ try {
+ final derivedNPub = bech32.encode(
+ Decoded(
+ prefix: 'npub',
+ words: bech32.toWords(Uint8List.fromList(hex.decode(hexkey))),
+ ),
+ );
+
+ return derivedNPub;
+ } catch (e) {
+ return null;
+ }
+}

pubspec.yaml

@@ -13,3 +13,4 @@ dependencies:
  bip340: ^0.0.4
  convert: ^3.1.1
  crypto: ^3.0.2
+ dart_bech32: ^2.0.0

test/utils_test.dart

@@ -0,0 +1,40 @@
+import 'package:nostr/nostr.dart';
+import 'package:test/test.dart';
+
+void main() {
+ const npubValid =
+ 'npub1eqmj85el4pkg7qdj2jcae24qykev5evnyz2s6pzdytzpkhga4u5sdmhexk';
+ const hexValid =
+ 'c83723d33fa86c8f01b254b1dcaaa025b2ca659320950d044d22c41b5d1daf29';
+
+ const npubInvalid =
+ 'nrub1eqmj85el4pkg7qdj2jcae24qykev5evnyz2s6pzdytzpkhga4u5sdmhexk';
+ const hexInvalid =
+ '_pub1eqmj85el4pkg7qdj2jcae24qykevdcaaa025b2ca6d22c41b5d1daf29';
+
+ group('Convert', () {
+ test('Npub to hex valid', () {
+ final hex = npubKeyToHex(npubValid);
+
+ expect(hex, hexValid);
+ });
+
+ test('Hex to npub valid', () {
+ final npub = hexKeyToNub(hexValid);
+
+ expect(npub, npub);
+ });
+
+ test('Npub to hex invalid', () {
+ final hex = npubKeyToHex(npubInvalid);
+
+ expect(hex, null);
+ });
+
+ test('Hex to npub invalid', () {
+ final npub = hexKeyToNub(hexInvalid);
+
+ expect(npub, null);
+ });
+ });
+}