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Server negotiates only the post-quantum hybrid X25519MLKEM768

Complete the handshake. A client whose first key share was classical must recover through HelloRetryRequest, which §4.1.4 requires it to answer with a second ClientHello carrying a share for the named group. A client that does not offer the group at all must abandon the attempt cleanly rather than stall — that is a correct outcome for a client without post-quantum support. A client that cannot negotiate the group at all never establishes a connection, so the server records no verdict and the result is `not run` rather than a pass or a failure. On this tier that reads as "no post-quantum key exchange", which is itself the finding: every other tier reaches `not run` only when the runner skipped something. curl/ngtcp2 1.11.0 lands here. This is the round trip that breaks first in a real migration, because it is the one that never happens until a server somewhere stops offering the classical group.

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⟨ QUANTUM ERROR PORTAL ⟩

Navigate the Error Dimensions

t-hybrid-only · RFC 8446 §4.1.4, draft-ietf-tls-hybrid-design · interoperability · layer tls · udp/4511 · MUST

Passing this means: Correctly decoded something valid but demanding.

Anomaly type: transport

How each client answered

ClientVersionVerdictWhat happened
curl ngtcp2/1.11.0 Not run Not attempted.
quinn noq fork Pass Decoded it and completed the request.
aioquic 1.3.0 Not run Not attempted.
chromium build 1223 Pass Decoded it and completed the request.
quic-go quic-go v0.61.0 Pass Decoded it and completed the request.
quiche 0.30.0 Pass Decoded it and completed the request.
neqo 0.31.1 Pass Decoded it and completed the request.

What the clause requires

Complete the handshake. A client whose first key share was classical must recover through HelloRetryRequest, which §4.1.4 requires it to answer with a second ClientHello carrying a share for the named group. A client that does not offer the group at all must abandon the attempt cleanly rather than stall — that is a correct outcome for a client without post-quantum support. A client that cannot negotiate the group at all never establishes a connection, so the server records no verdict and the result is `not run` rather than a pass or a failure. On this tier that reads as "no post-quantum key exchange", which is itself the finding: every other tier reaches `not run` only when the runner skipped something. curl/ngtcp2 1.11.0 lands here. This is the round trip that breaks first in a real migration, because it is the one that never happens until a server somewhere stops offering the classical group.

Judged against RFC 8446.

Run this one yourself

Every test is reachable from your own client. Nothing here needs an account.

curl -s https://conformance.pqcrypta.com/catalog.json \
  | jq '.tests[] | select(.id == "t-hybrid-only")'

What this suite is · The full grid · All clients · All tests · Findings