178d2d00ab
- Flutter app (Android/iOS): home, explore, albums, search, player with equalizer, mini player, sign up/sign in with email codes, profile, encrypted offline downloads, About page - server/: one-command deploy of self-hosted Supabase behind HestiaCP/nginx (or Caddy), migrations, backups, email templates - supabase/migrations: schema, row-level security, profiles - tools/: song scanner and importer Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
54 lines
1.6 KiB
Dart
54 lines
1.6 KiB
Dart
import 'dart:math';
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import 'dart:typed_data';
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import 'package:pointycastle/export.dart';
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/// AES-256 in counter mode, so any byte range of a song can be decrypted on
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/// its own (seeking without reading the whole file). Encrypting and decrypting
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/// are the same operation.
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///
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/// File layout: 8-byte random nonce, then the encrypted song.
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class SongCipher {
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SongCipher(Uint8List key) : _aes = AESEngine()..init(true, KeyParameter(key));
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static const headerLength = 8;
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static const _block = 16;
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final AESEngine _aes;
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static Uint8List newNonce() {
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final r = Random.secure();
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return Uint8List.fromList(List.generate(headerLength, (_) => r.nextInt(256)));
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}
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static Uint8List newKey() {
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final r = Random.secure();
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return Uint8List.fromList(List.generate(32, (_) => r.nextInt(256)));
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}
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/// XORs [data] with the key stream for song position [offset] (bytes after the header), in place.
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void apply(Uint8List data, int offset, Uint8List nonce) {
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final counter = Uint8List(_block)..setRange(0, headerLength, nonce);
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final stream = Uint8List(_block);
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var blockIndex = -1;
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for (var i = 0; i < data.length; i++) {
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final pos = offset + i;
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final b = pos ~/ _block;
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if (b != blockIndex) {
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blockIndex = b;
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_writeCounter(counter, b);
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_aes.processBlock(counter, 0, stream, 0);
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}
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data[i] ^= stream[pos % _block];
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}
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}
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static void _writeCounter(Uint8List counter, int blockIndex) {
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var v = blockIndex;
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for (var i = _block - 1; i >= headerLength; i--) {
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counter[i] = v & 0xff;
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v >>= 8;
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}
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}
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}
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