In today's world, speed and safety are key priorities. That is why Google developed the QUIC (Quick UDP Internet Connections) protocol, which later formed the basis of HTTP/3. QUIC is designed to replace the outdated TCP, offering faster and more reliable data transmission.
Is QUIC the future of the Internet?
Fast connection establishment
TCP requires a three-step handshake (SYN, SYN-ACK, ACK), which increases latency. QUIC uses UDP and reduces this process to a single packet exchange by preserving the connection state (including cryptographic keys) between sessions.
Built-in encryption
Unlike TCP, where TLS is a separate layer, QUIC encrypts all data by default, including metadata. This makes attacks based on traffic analysis more difficult.
Packet loss tolerance
QUIC uses stream multiplexing: if one packet is lost, it does not block the entire transmission (as in TCP), but only affects a specific stream.
Migration of the connection without interruption
If you switch from Wi-Fi to mobile Internet, QUIC can continue the connection without shaking hands again, since the connection identifier is not linked to an IP address, but to a cryptographic token.
How does QUIC work from the inside?
QUIC runs on top of UDP (port 443 by default), but adds its own mechanisms.:
Connection ID is a unique session identifier that allows you to resume the connection when changing the network.
Packet Number – instead of sequential numbers, as in TCP, QUIC uses independent numbering to protect against attacks.
Frames – data is transmitted in the form of "frames" (STREAM, ACK, CRYPTO, etc.), which makes the protocol flexible. 0-RTT Handshake – the ability to send data in the first packet when reconnecting.
➡ QUIC vulnerabilities and issues
Attacks on 0-RTT
The 0-RTT (Zero Round-Trip Time) mode allows you to resume the session without shaking hands again, but this makes QUIC vulnerable to replay attacks. An attacker can intercept and resend an encrypted packet, which is especially dangerous for financial transactions.
Blocking QUIC with firewalls
Since QUIC runs on top of UDP, some corporate and government firewalls block it, considering it suspicious. This can lead to a denial of service.
Load balancing issues
Some load balancing systems don't work well with QUIC because they don't always handle the Connection ID correctly. This can lead to connection failures.
Risks of deanonymization
The Connection ID can be used to track users, even if the IP address is changing (for example, in a VPN).
DDoS attacks via UDP
UDP does not require connection confirmation, which makes QUIC a potential target for enhanced DDoS attacks.
