ngtcp2 — A second key update after the first is acknowledged

Pass

Decoded it and completed the request.

The client did what the clause requires.

What was measured

Client

ngtcp2 — ngtcp2 + nghttp3 (direct), 3c23148

Test

A second key update after the first is acknowledged — q-key-update-repeated

Clause

RFC 9001 §6.1, §6.5 (MUST)

Class

interoperability — Correctly decoded something valid but demanding.

Required behaviour

Follow both updates and carry on. §6.1 lets an endpoint update again once the previous phase has been acknowledged, so a long-lived connection changes keys repeatedly and a client has to track the phase rather than assume one change. Distinct from the single update on the neighbouring port. An implementation that hardcodes the first transition — treating key phase as a one-way flag rather than a bit that alternates — passes that test and fails here, which is precisely the bug worth finding.

Measured

2026-09-18

Reproduce it

The suite is the judge, so the reproduction is to point the same client at the same test and let the server report what it saw.

SESSION=$(curl -sX POST https://conformance.pqcrypta.com/session | jq -r .id)
# then drive ngtcp2 at the test URL and read the verdict:
curl -s https://conformance.pqcrypta.com/report/$SESSION.json | jq '.results["q-key-update-repeated"]'