TLS 1.3 0-RTT Replay Safety and Middlebox Interception Benchmarks

TLS 1.3 enables 0-RTT early data resumption using pre-shared keys (PSK), effectively reducing the connection handshake from two round trips down to zero additional trips for the application payload. On a 150ms transpacific link, this shaves 300ms off total request latency.

However, middlebox interference remains non-trivial. Across our synthetic probe network testing 42 global routes, 3.8% of paths experienced silent connection resets when the ClientHello contained early data extensions. We implemented a dynamic fallback policy: if a peer fails 0-RTT negotiation twice within 10 minutes, the client automatically downgrades to standard 1-RTT resumption for that target AS.