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.
54 lines
1.6 KiB
Dart
54 lines
1.6 KiB
Dart
/// Self-contained bech32 encode (BIP-173 checksum), enough for NIP-19
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/// `npub`/`nsec`. Written inline to avoid a dependency's version quirks; NIP-19
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/// is plain bech32 (checksum constant 1), not bech32m.
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const _charset = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l';
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int _polymod(List<int> values) {
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const gen = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3];
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var chk = 1;
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for (final v in values) {
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final top = chk >> 25;
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chk = ((chk & 0x1ffffff) << 5) ^ v;
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for (var i = 0; i < 5; i++) {
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if ((top >> i) & 1 == 1) chk ^= gen[i];
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}
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}
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return chk;
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}
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List<int> _hrpExpand(String hrp) => [
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...hrp.codeUnits.map((c) => c >> 5),
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0,
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...hrp.codeUnits.map((c) => c & 31),
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];
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List<int> _createChecksum(String hrp, List<int> data) {
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final values = [..._hrpExpand(hrp), ...data, 0, 0, 0, 0, 0, 0];
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final mod = _polymod(values) ^ 1;
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return List.generate(6, (i) => (mod >> (5 * (5 - i))) & 31);
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}
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/// Converts 8-bit bytes to 5-bit groups (bech32 payload), padding with zeros.
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List<int> _convertBits8to5(List<int> data) {
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var acc = 0;
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var bits = 0;
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final out = <int>[];
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for (final value in data) {
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acc = (acc << 8) | value;
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bits += 8;
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while (bits >= 5) {
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bits -= 5;
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out.add((acc >> bits) & 31);
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}
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}
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if (bits > 0) out.add((acc << (5 - bits)) & 31);
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return out;
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}
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/// bech32-encodes [data] (raw bytes) under [hrp] (e.g. `npub`).
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String bech32Encode(String hrp, List<int> data) {
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final five = _convertBits8to5(data);
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final checksum = _createChecksum(hrp, five);
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final combined = [...five, ...checksum];
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return '${hrp}1${combined.map((v) => _charset[v]).join()}';
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}
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