nostr_tools

Description:

nostr tools

A Dart package that makes it easy to work with the nostr protocol and develop nostr clients.
Usage #
To use this package, add nostr_tools as a dependency in your pubspec.yaml file.
Generating a private key and a public key #
import 'package:nostr_tools/nostr_tools.dart';

void main() {
final keyGenerator = KeyApi();

final privateKey = keyGenerator.generatePrivateKey();
print('[+] privateKey: $privateKey');
// [+] privateKey: b2352adb186508e7f617105a6dc070df531f53b56cf8744816fdb838891dc9b7

final publicKey = keyGenerator.getPublicKey(privateKey);
print('[+] publicKey: $publicKey');
// [+] publicKey: 9d088c4377b9866fad945d949de8f626784b1639f93bf090c1cea6727f17dd51
}
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Creating, signing and verifying events #
import 'package:nostr_tools/nostr_tools.dart';

void main() {
final keyApi = KeyApi();
final eventApi = EventApi();

final privateKey = keyApi.generatePrivateKey();
final publicKey = keyApi.getPublicKey(privateKey);

final event = Event(
kind: 1,
tags: [],
content: 'content',
created_at: DateTime.now().millisecondsSinceEpoch ~/ 1000,
pubkey: publicKey,
);

event.id = eventApi.getEventHash(event);
event.sig = eventApi.signEvent(event, privateKey);

if (eventApi.verifySignature(event)) print('[+] sig is valid');
}
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Interacting with a relay #
void main() async {
final relay = RelayApi(relayUrl: 'wss://relay.damus.io');

final stream = await relay.connect();

relay.on((event) {
if (event == RelayEvent.connect) {
print('[+] connected to ${relay.relayUrl}');
} else if (event == RelayEvent.error) {
print('[!] failed to connect to ${relay.relayUrl}');
}
});

relay.sub([
Filter(
kinds: [1],
limit: 10,
since: DateTime.now().millisecondsSinceEpoch ~/ 1000,
)
]);

stream.listen((Message message) {
if (message.type == 'EVENT') {
Event event = message.message;
print('[+] Received event: ${event.content}');
} else if (message.type == 'OK') {
print('[+] Event Published: ${message.message}');
}
});

// let's publish a new event while simultaneously monitoring the relay for it
final privateKey =
'b2352adb186508e7f617105a6dc070df531f53b56cf8744816fdb838891dc9b7';

final event = EventApi().finishEvent(
Event(
kind: 1,
tags: [],
content: 'hello world',
created_at: DateTime.now().millisecondsSinceEpoch ~/ 1000,
),
privateKey,
);

relay.publish(event);
}
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Interacting with multiple relays #
void main() async {
final relaysList = [
'wss://relay.damus.io',
'wss://relay.nostr.info',
'wss://eden.nostr.land',
'wss://nostr-pub.wellorder.net',
'wss://nos.lol'
];
final relayPool = RelayPoolApi(relaysList: relaysList);

final stream = await relayPool.connect();

relayPool.on((event) {
if (event == RelayEvent.connect) {
print('[+] connected to: ${relayPool.connectedRelays}');
} else if (event == RelayEvent.error) {
print('[!] failed to connect to: ${relayPool.failedRelays}');
}
});

relayPool.sub([
Filter(
kinds: [1],
limit: 10,
since: DateTime.now().millisecondsSinceEpoch ~/ 1000,
)
]);

stream.listen((Message message) {
if (message.type == 'EVENT') {
Event event = message.message;
print('[+] Received event: ${event.content}');
}
});

final privateKey =
'ccbe92bd853e3661bace63df5b8338dcbaa2c766e2dbb0b90d45b2dd58efaae4';

final event = EventApi().finishEvent(
Event(
kind: 1,
tags: [],
content: 'hello world',
created_at: DateTime.now().millisecondsSinceEpoch ~/ 1000,
),
privateKey,
);

relayPool.publish(event);
}
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Querying profile data from a NIP-05 address #
void main() async {
var nip05 = Nip05();
var profile = await nip05.queryProfile('[email protected]');
print('[+] Pubkey: ${profile?.pubkey}');
// [+] Pubkey: c7c187ba76532d55723490af88e76dd570fe551a2461ca9ab542b503bbb25045

print('[+] Relays: ${profile?.relays}');
// [+] Relays: [wss://relay.damus.io, wss://nos.lol, wss://relay.snort.social]
}
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Encoding and decoding NIP-19 codes #
void main() {
final keyGenerator = KeyApi();
final nip19 = Nip19();

final sk = keyGenerator.generatePrivateKey();
final nsec = nip19.nsecEncode(sk);
final nsecDecoded = nip19.decode(nsec);
assert(nsecDecoded['type'] == 'nsec');
assert(nsecDecoded['data'] == sk);

final pk = keyGenerator.getPublicKey(sk);
final npub = nip19.npubEncode(pk);
final npubDecoded = nip19.decode(npub);
assert(npubDecoded['type'] == 'npub');
assert(npubDecoded['data'] == pk);

final relays = [
'wss://relay.nostr.example.mydomain.example.com',
'wss://nostr.banana.com'
];
final nprofile =
nip19.nprofileEncode(ProfilePointer(pubkey: pk, relays: relays));
final nprofileDecode = nip19.decode(nprofile);
assert(nprofileDecode['type'] == 'nprofile');
assert(nprofileDecode['data']['pubkey'] == pk);
assert(nprofileDecode['data']['relays'].length == 2);
}
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Encrypting and decrypting direct messages #
void main() {
final keyGenerator = KeyApi();
final nip04 = Nip04();

final aliceSK = keyGenerator.generatePrivateKey();
final alicePK = keyGenerator.getPublicKey(aliceSK);
final bobSK = keyGenerator.generatePrivateKey();
final bobPK = keyGenerator.getPublicKey(bobSK);

var aliceMessageToBob = 'Hello Bob!';
var cipherText = nip04.encrypt(aliceSK, bobPK, aliceMessageToBob);
print('[+] cipherText: $cipherText');

var bobDecodingMessage = nip04.decrypt(bobSK, alicePK, cipherText);
print('[+] plainText: $bobDecodingMessage');
}
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Take a look at the example project for developing a simple basic nostr client in flutter.
Reference #

nips