dateKeys-dart/test/encrypt3_test.dart

// The writer of capsules beyond the vectors of Go: what reaches the sink and
// when, the errors of the sink, of the sources and of the hooks with their
// codes, the strings that Go cannot hold, and the result. The seeded source
// keeps them on Node.js too.

import 'dart:async';
import 'dart:convert';
import 'dart:typed_data';

import 'package:datekeys/datekeys.dart';
import 'package:test/test.dart';

import 'capsule_writer_support.dart';
import 'vectors/capsule_writer.g.dart';

final Json doc = jsonDecode(capsuleWriterJson) as Json;

Json caseNamed(String name) =>
    listOf(doc['cases'])
        .firstWhere((c) => (c['recipe']! as Json)['name'] == name);

EncryptOptions small({
  RandomSource? random,
  AccessPolicy policy = AccessPolicy.timeOnly,
  bool portable = false,
  AuthorSigner? authorKey,
  CmsSigner? cmsSigner,
  Sealer? sealer,
  String comment = '',
}) => EncryptOptions(
  profile: quicknet(),
  unlockAt: roundTime(quicknet(), 1000),
  now: () => genesis,
  policy: policy,
  newPortableKey: portable,
  authorKey: authorKey,
  cmsSigner: cmsSigner,
  sealer: sealer,
  comment: comment,
  testVectors: true,
  testAreaLen: 512,
  random: random ?? seeded('encrypt3 test'),
);

/// A sink that fails at its add number [failAt], or at close.
final class FailingSink implements ByteSink {
  FailingSink({this.failAt, this.failClose = false});

  final int? failAt;
  final bool failClose;
  int adds = 0;
  Object? aborted;
  bool closed = false;

  @override
  void add(Uint8List bytes) {
    if (++adds == failAt) throw const TextError('disk full');
  }

  @override
  void close() {
    if (failClose) throw const TextError('cannot rename');
    closed = true;
  }

  @override
  void abort(Object reason) => aborted = reason;
}

/// The author key of the case of alg 1, which records whether anything of
/// the capsule had reached the sink when it was asked to sign.
final class WatchingKey implements AuthorSigner {
  WatchingKey(this.hooks, this.sink);

  final Json hooks;
  final CapsuleSink sink;
  int? addsWhenSigning;

  @override
  Uint8List get publicKey => hexOf(hooks['author_public']);

  @override
  Future<Uint8List> sign(Uint8List message) async {
    addsWhenSigning = sink.adds;
    expect(toHex(message), hooks['author_message']);
    return hexOf(hooks['author_signature']);
  }
}

final class ThrowingSigner implements CmsSigner, Sealer {
  ThrowingSigner(this.error);

  final Object error;

  @override
  List<Uint8List> get signers => [Uint8List(32)];

  @override
  Uint8List sign(Uint8List message) => throw error;

  @override
  Uint8List seal(Uint8List subject) => throw error;
}

void main() {
  test(
    'nothing reaches the sink before the signature, which is awaited',
    () async {
      final c = caseNamed('signed with alg 1, area of 512');
      final r = c['recipe']! as Json;
      final sink = CapsuleSink();
      final key = WatchingKey(c['hooks']! as Json, sink);
      final res = await encryptFiles(
        sink,
        sourcesOf(r),
        small(random: seeded(r['seed']! as String), authorKey: key),
      );
      expect(key.addsWhenSigning, 0);
      expect(sink.closed, isTrue);
      expect(toHex(sink.bytes), (c['written']! as Json)['dkc']);
      expect(res.head.files.single.path, 'nota.txt');
    },
  );

  test('the sink receives the prelude first, then the header and the rest, '
      'each buffer its own', () async {
    final sink = CapsuleSink();
    final parts = <Uint8List>[];
    final res = await encryptFiles(_Tee(sink, parts), [
      FileSource.bytes('a.txt', utf8.encode('a')),
    ], small());
    expect(parts.first.length, 16);
    expect(ascii.decode(parts.first.sublist(0, 4)), 'DKC1');
    // No two parts share a buffer.
    final buffers = {for (final p in parts) p.buffer};
    expect(buffers.length, parts.length);
    expect(sink.closed, isTrue);
    expect(res.head.files.single.size, 1);
  });

  test(
    'a sink that fails stops the writing, with its error, and is aborted',
    () async {
      for (final at in [1, 2, 3, 4, 5]) {
        final sink = FailingSink(failAt: at);
        await expectLater(
          encryptFiles(sink, [
            FileSource.bytes('a.txt', utf8.encode('a')),
          ], small()),
          throwsA(isA<TextError>()),
        );
        expect(sink.adds, at);
        expect(sink.aborted, isA<TextError>());
        expect(sink.closed, isFalse);
      }
    },
  );

  test('a sink that fails to close is not aborted', () async {
    final sink = FailingSink(failClose: true);
    await expectLater(
      encryptFiles(sink, [
        FileSource.bytes('a.txt', utf8.encode('a')),
      ], small()),
      throwsA(isA<TextError>()),
    );
    expect(sink.aborted, isNull);
  });

  test(
    'a hook or a source that throws a DateKeysException keeps its code',
    () async {
      final e = DateKeysException(ErrorCode.accessInvalid, 'hook');
      for (final (opts, want) in [
        (
          small(cmsSigner: ThrowingSigner(e)),
          'capsule: signing: hook: ERR_ACCESS_INVALID',
        ),
        (
          small(sealer: ThrowingSigner(e)),
          'capsule: sealing: hook: ERR_ACCESS_INVALID',
        ),
      ]) {
        final sink = CapsuleSink();
        await expectLater(
          encryptFiles(sink, [
            FileSource.bytes('a', const [1]),
          ], opts),
          throwsA(
            isA<DateKeysException>()
                .having((x) => x.message, 'message', want)
                .having((x) => x.code, 'code', ErrorCode.accessInvalid),
          ),
        );
        expect(sink.adds, 0);
        expect(sink.aborted, isNotNull);
      }
      final src = FileSource(path: 'a', size: 1, open: () => Stream.error(e));
      await expectLater(
        encryptFiles(CapsuleSink(), [src], small()),
        throwsA(
          isA<DateKeysException>().having(
            (x) => x.message,
            'message',
            'capsule: file "a": hook: ERR_ACCESS_INVALID',
          ),
        ),
      );
      // Anything else is a CapsuleWriteException with its text and its cause.
      final cause = StateError('broken');
      final src2 = FileSource(path: 'b', size: 1, open: () => throw cause);
      await expectLater(
        encryptFiles(CapsuleSink(), [src2], small()),
        throwsA(
          isA<CapsuleWriteException>()
              .having(
                (x) => x.message,
                'message',
                'capsule: file "b": Bad state: broken',
              )
              .having((x) => x.cause, 'cause', same(cause)),
        ),
      );
    },
  );

  test(
    'a path or a text that is not well-formed UTF-16 is not UTF-8 for Go',
    () async {
      Future<String> rejection(
        List<FileSource> files, {
        String comment = '',
      }) async {
        try {
          await encryptFiles(CapsuleSink(), files, small(comment: comment));
        } on ArgumentError catch (e) {
          return '${e.message}';
        }
        throw StateError('no error');
      }

      expect(
        await rejection([
          FileSource.bytes('a\uD800', const [1]),
        ]),
        r'capsule: path "a\xed\xa0\x80": R1: not valid UTF-8',
      );
      expect(
        await rejection([
          FileSource.bytes('a', const [1]),
        ], comment: 'x\uDC00'),
        'capsule: comment: not valid UTF-8',
      );
    },
  );

  test('a source is read in streaming: what it gives reaches the sink before '
      'it gives much more', () async {
    const chunk = 16 << 10;
    const chunks = 64;
    var given = 0;
    var maxAhead = 0;
    final sink = _SlowSink();
    Stream<List<int>> open() async* {
      for (var i = 0; i < chunks; i++) {
        given += chunk;
        final ahead = given - sink.received;
        if (ahead > maxAhead) maxAhead = ahead;
        yield Uint8List(chunk);
      }
    }

    final src = FileSource(
      path: 'big',
      size: chunk * chunks,
      open: () {
        given = 0;
        maxAhead = 0;
        return open();
      },
    );
    await encryptFiles(sink, [src], small());
    // The second reading: at most a STREAM chunk of 64 KiB is held, with
    // the bytes of the frame, the area and the head that precede the file,
    // and the piece being given.
    expect(maxAhead, lessThan((64 << 10) + 2 * chunk + 4096));
    expect(given, chunk * chunks);
  });

  test(
    'the result describes the capsule written, and its .dkk opens it',
    () async {
      final c = caseNamed('time_and_key, a portable key');
      final r = c['recipe']! as Json;
      final w = await writeRecipe(r, const {});
      final res = w.result!;
      expect(res.format, CapsuleFormat.format3);
      expect(res.dateKey.toString(), startsWith('dk1_'));
      expect(res.unlockAt, roundTime(quicknet(), 1000));
      expect(res.paddedLength, paddedLength(res.length, PaddingRule.reforzado));
      final k = res.portableKey!;
      expect(k.capsuleId, res.capsuleId);
      expect(k.verification!.capsuleDigest, sha256Of(w.dkc));
      expect(k.critical, isEmpty);
      expect(k.noncritical, isEmpty);
    },
  );

  test('the options keep their defaults', () {
    final o = EncryptOptions(
      profile: quicknet(),
      unlockAt: genesis,
      now: () => genesis,
    );
    expect(o.policy, AccessPolicy.timeOnly);
    expect(o.padding, isNull);
    expect(o.random, same(secureRandom));
    expect(o.testAreaLen, 0);
    expect(o.recipients, isEmpty);
    expect(o.words, isEmpty);
  });
}

final class _Tee implements ByteSink {
  _Tee(this.sink, this.parts);

  final CapsuleSink sink;
  final List<Uint8List> parts;

  @override
  void add(Uint8List bytes) {
    parts.add(bytes);
    sink.add(bytes);
  }

  @override
  void close() => sink.close();

  @override
  void abort(Object reason) => sink.abort(reason);
}

/// A sink that takes its time, and counts the bytes of PAYLOAD_AGE it
/// received, as plaintext: each chunk of the STREAM is 16 bytes more.
final class _SlowSink implements ByteSink {
  int received = 0;
  bool _payload = false;
  int _adds = 0;

  @override
  Future<void> add(Uint8List bytes) async {
    await Future<void>.delayed(Duration.zero);
    // The prelude, the header, SEALED_CONTROL, then the header and the
    // nonce of PAYLOAD_AGE, then its chunks.
    if (++_adds > 5) _payload = true;
    if (_payload) received += bytes.length - 16;
  }

  @override
  void close() {}

  @override
  void abort(Object reason) {}
}