mirror of
https://gitlab.com/veilid/veilidchat.git
synced 2024-12-12 01:24:30 -05:00
75 lines
2.5 KiB
Dart
75 lines
2.5 KiB
Dart
import 'dart:convert';
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import 'dart:typed_data';
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import 'package:protobuf/protobuf.dart';
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import 'package:veilid_support/veilid_support.dart';
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import '../../../proto/proto.dart' as proto;
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class MessageIntegrity {
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MessageIntegrity._({
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required TypedKey author,
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required VeilidCryptoSystem crypto,
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}) : _author = author,
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_crypto = crypto;
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static Future<MessageIntegrity> create({required TypedKey author}) async {
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final crypto = await Veilid.instance.getCryptoSystem(author.kind);
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return MessageIntegrity._(author: author, crypto: crypto);
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}
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////////////////////////////////////////////////////////////////////////////
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// Public interface
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Future<Uint8List> generateMessageId(proto.Message? previous) async {
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if (previous == null) {
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// If there's no last sent message,
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// we start at a hash of the identity public key
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return _generateInitialId();
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} else {
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// If there is a last message, we generate the hash
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// of the last message's signature and use it as our next id
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return _hashSignature(previous.signature);
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}
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}
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Future<void> signMessage(
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proto.Message message,
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SecretKey authorSecret,
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) async {
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// Ensure this message is not already signed
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assert(!message.hasSignature(), 'should not sign message twice');
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// Generate data to sign
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final data = Uint8List.fromList(utf8.encode(message.writeToJson()));
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// Sign with our identity
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final signature = await _crypto.sign(_author.value, authorSecret, data);
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// Add to the message
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message.signature = signature.toProto();
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}
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Future<bool> verifyMessage(proto.Message message) async {
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// Ensure the message is signed
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assert(message.hasSignature(), 'should not verify unsigned message');
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final signature = message.signature.toVeilid();
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// Generate data to sign
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final messageNoSig = message.deepCopy()..clearSignature();
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final data = Uint8List.fromList(utf8.encode(messageNoSig.writeToJson()));
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// Verify signature
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return _crypto.verify(_author.value, data, signature);
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}
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////////////////////////////////////////////////////////////////////////////
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// Private implementation
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Future<Uint8List> _generateInitialId() async =>
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(await _crypto.generateHash(_author.decode())).decode();
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Future<Uint8List> _hashSignature(proto.Signature signature) async =>
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(await _crypto.generateHash(signature.toVeilid().decode())).decode();
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////////////////////////////////////////////////////////////////////////////
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final TypedKey _author;
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final VeilidCryptoSystem _crypto;
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}
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