dateKeys-dart/test/der_vectors_test.dart

// The DER elements of the security areas of security_cms.json, the
// signatures and the tokens, as the seeds of FuzzDERCheck of datekeys-go:
// check accepts each, split, content and parseTime read it element by
// element, and so for every mutation of them that check accepts.
@TestOn('vm')
library;

import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'dart:typed_data';

import 'package:datekeys/datekeys.dart' show fromHex;
import 'package:datekeys/src/der.dart' as der;
import 'package:test/test.dart';

import 'der_support.dart';

/// The outermost runs of bytes of [b] that are one DER SEQUENCE of more than
/// 127 bytes each, as derElements of der_test.go.
List<Uint8List> derElements(Uint8List b) {
  final out = <Uint8List>[];
  for (var i = 0; i + 2 < b.length; i++) {
    if (b[i] != 0x30 || b[i + 1] < 0x81 || b[i + 1] > 0x83) continue;
    final rest = Uint8List.sublistView(b, i);
    final Uint8List element;
    try {
      final content = der.content(rest);
      final headerLength = content.offsetInBytes - rest.offsetInBytes;
      element = Uint8List.sublistView(b, i, i + headerLength + content.length);
      der.check(element);
    } on der.DerException {
      continue;
    }
    out.add(element);
    i += element.length - 1;
  }
  return out;
}

void main() {
  final file = jsonDecode(
    File('testdata/vectors/security_cms.json').readAsStringSync(),
  ) as Map<String, Object?>;
  final areas = [
    for (final c in (file['cases']! as List).cast<Map<String, Object?>>())
      fromHex(c['security_cbor']! as String),
  ];
  final seeds = [for (final a in areas) ...derElements(a)];

  test('the signatures and tokens of security_cms.json are DER', () {
    expect(areas, isNotEmpty);
    // Some cases hold no DER on purpose: a signature that is not a CMS, a
    // seal that is not DER, SIGNERS out of order or empty.
    expect(seeds, isNotEmpty);
    seeds.forEach(walkAccepted);
  });

  test('what check accepts of their mutations, the readers read', () {
    final r = Random(8);
    var accepted = 0;
    for (var i = 0; i < 3000; i++) {
      final b = mutateDer(r, seeds[r.nextInt(seeds.length)]);
      try {
        der.check(b);
      } on der.DerException {
        continue;
      }
      accepted++;
      walkAccepted(b);
    }
    expect(accepted, greaterThan(0));
  });
}