halkyon/packages/halkyon_app/test/privacy/sodium_content_cipher_test.dart

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

import 'package:flutter_test/flutter_test.dart';
import 'package:halkyon_app/halkyon_app.dart';

/// Content sealed with a data key (ADR 0019), with libsodium as its build
/// hook compiles it.
void main() {
  final crypto = SodiumAccountCrypto();
  late UnlockedAccountKeys alice;
  late UnlockedAccountKeys bob;
  late SodiumContentCipher device;

  final context = utf8.encode('card_revision/0192/payload');
  final plain = Uint8List.fromList(utf8.encode('{"front":"火"}'));

  setUpAll(() async {
    alice = await crypto.newDeviceKeys();
    bob = await crypto.newDeviceKeys();
  });

  setUp(() async {
    device = SodiumContentCipher();
    await device.unlock(alice);
  });

  tearDown(() => device.dispose());

  test("a key made on one device opens on another of the account's, and "
      'what it seals opens there', () async {
    final sealedKey = device.newKey('studyset-1');
    final sealed = device.seal(plain, keyId: 'studyset-1', context: context);

    final other = SodiumContentCipher();
    await other.unlock(alice);
    addTearDown(other.dispose);
    expect(other.has('studyset-1'), isFalse);
    expect(other.openKey('studyset-1', sealedKey), isTrue);

    expect(other.has('studyset-1'), isTrue);
    expect(other.unseal(sealed, context: context), plain);
    expect(sealed.keyId, 'studyset-1');
    expect(String.fromCharCodes(sealed.payload), isNot(contains('front')));
  });

  test("another account's device opens neither the key nor what it "
      'sealed', () async {
    final sealedKey = device.newKey('studyset-1');
    final sealed = device.seal(plain, keyId: 'studyset-1', context: context);

    final bobs = SodiumContentCipher();
    await bobs.unlock(bob);
    addTearDown(bobs.dispose);

    expect(bobs.openKey('studyset-1', sealedKey), isFalse);
    expect(bobs.unseal(sealed, context: context), isNull);
  });

  test('a key opens only under the ID it was sealed with, and only once '
      'the account is unlocked', () async {
    final sealedKey = device.newKey('studyset-1');
    final other = SodiumContentCipher();
    addTearDown(other.dispose);

    expect(() => other.openKey('studyset-1', sealedKey), throwsStateError);
    await other.unlock(alice);
    expect(other.openKey('studyset-2', sealedKey), isFalse);
    expect(other.openKey('studyset-1', sealedKey), isTrue);
  });

  test('a payload moved to another row, or changed, opens no more', () {
    device.newKey('studyset-1');
    final sealed = device.seal(plain, keyId: 'studyset-1', context: context);
    final changed = Uint8List.fromList(sealed.payload)..last ^= 1;

    expect(
      device.unseal(sealed, context: utf8.encode('card_revision/0193/payload')),
      isNull,
    );
    expect(
      device.unseal(
        SealedPayload(
          keyId: sealed.keyId,
          nonce: sealed.nonce,
          payload: changed,
        ),
        context: context,
      ),
      isNull,
    );
    expect(device.unseal(sealed, context: context), plain);
  });

  test('without its key nothing opens, nor is sealed', () {
    final sealed = SealedPayload(
      keyId: 'unknown',
      nonce: Uint8List(24),
      payload: Uint8List(100),
    );

    expect(device.unseal(sealed, context: context), isNull);
    expect(
      () => device.seal(plain, keyId: 'unknown', context: context),
      throwsStateError,
    );
  });
}