0RTT
0-RTT, or zero round-trip time, is a technique used in TLS 1.3 and QUIC to reduce connection latency by allowing the client to send application data before the handshake completes. This is possible when the client has a previously established session with the same server and presents a pre-shared key or session resumption ticket. The server, using this material, can decrypt and process the early data without waiting for a full handshake to finish.
In TLS 1.3, 0-RTT data is optional and subject to security considerations. Early data is protected with
In QUIC, 0-RTT is integrated into the protocol so a client can send application data as part
Operational notes: Because of security risks, 0-RTT may be disabled by default on many servers or libraries;