ls projects/

1@Service
2public class CryptoQRService {
3
4    @Autowired
5    private CryptographicEngine cryptoEngine;
6
7    public SecureQRCode generateSecureQRCode(VehicleData vehicle) {
8        // Multi-layer encryption
9        String encrypted = cryptoEngine.encryptAES256(
10            vehicle.toString(),
11            generateUniqueKey()
12        );
13
14        // Digital signature with government private key
15        String signature = cryptoEngine.signWithRSA(
16            encrypted,
17            getGovernmentPrivateKey()
18        );
19
20        // Generate unfalsifiable QR code
21        QRCodeData qrData = new QRCodeData()
22            .setEncryptedData(encrypted)
23            .setSignature(signature)
24            .setTimestamp(Instant.now())
25            .setVehicleId(vehicle.getId());
26
27        return qrCodeGenerator.create(qrData, QRErrorLevel.HIGH);
28    }
29
30    public boolean validateQRCode(String qrContent) {
31        return cryptoEngine.verifySignature(
32            qrContent,
33            getGovernmentPublicKey()
34        );
35    }
36}

1@Service
2@RequiredArgsConstructor
3public class ProductCacheService {
4
5    private final RedissonClient redissonClient;
6    private final Cache<Long, ProductDTO> caffeineCache;
7
8    @Cacheable(value = "products", key = "#id")
9    public ProductDTO getProductById(Long id) {
10        // L1: Check Caffeine (1-5ms)
11        ProductDTO cached = caffeineCache.getIfPresent(id);
12        if (cached != null) return cached;
13
14        // L2: Check Redis with distributed lock
15        RLock lock = redissonClient.getLock("lock:product:" + id);
16        try {
17            if (lock.tryLock(5, 10, TimeUnit.SECONDS)) {
18                // Only 1 thread queries DB (prevents stampede)
19                ProductDTO product = fetchFromDatabase(id);
20                caffeineCache.put(id, product);
21                return product;
22            }
23        } finally {
24            lock.unlock();
25        }
26        return fetchFromDatabase(id);
27    }
28}