vjrj
49b872b405
Throwaway research spike (spike/ branch, outside pub workspace, no prod deps touched). Validates the open Block 2 decisions before committing a funded round: 1. Deterministic one-way secp256k1 (Nostr) key derived from the Ğ1 root seed via HKDF — user still backs up ONE thing. Reproducible + signs (BIP340). 2. OfferTransport abstraction over Nostr NIP-99 (kind 30402); Offer stays inventory/location-agnostic, geohash coarsened on the wire (tested). 3. publish->discover-by-geohash proven end-to-end against an in-process hermetic mini-relay (~34ms round-trip). Findings + risks + recommendation in docs/design/spike-block2-findings.md. Block 1 suite untouched. 14 tests green, analyzer clean.
32 lines
1,011 B
Dart
32 lines
1,011 B
Dart
import 'dart:typed_data';
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import 'package:crypto/crypto.dart';
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/// Minimal, self-contained HKDF-SHA256 (RFC 5869), synchronous.
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///
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/// Spike-local so the derivation stays pure Dart and easy to reason about. In
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/// production this would reuse `commons_core`'s `Hkdf` (the `cryptography`
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/// package already ships one — see backup_box.dart), keyed by a domain string.
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Uint8List hkdfSha256({
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required List<int> ikm,
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required String info,
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List<int> salt = const [],
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int length = 32,
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}) {
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// Extract.
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final actualSalt = salt.isEmpty ? Uint8List(32) : salt; // HashLen zeros
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final prk = Hmac(sha256, actualSalt).convert(ikm).bytes;
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// Expand.
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final infoBytes = info.codeUnits;
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final out = <int>[];
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var previous = <int>[];
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var counter = 1;
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while (out.length < length) {
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final input = <int>[...previous, ...infoBytes, counter];
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previous = Hmac(sha256, prk).convert(input).bytes;
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out.addAll(previous);
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counter++;
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}
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return Uint8List.fromList(out.sublist(0, length));
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}
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