Participant Relationship Protocol

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K01-LP: Yes

Rationale

The previously unspecified end-to-end group now has an explicit versioned witness. Go 1.26.5 selects X25519MLKEM768 with both modern endpoints under the default preference list. Its pinned key schedule concatenates the ML-KEM shared secret followed by the X25519 secret and passes that result into the TLS 1.3 handshake-secret derivation; the client performs the matching decapsulation and concatenation. The official libp2p TLS identity component retains certificate-chain and expected-Peer-ID verification and disables session tickets. A local QUIC execution using that component negotiated group 4588 at both ends, authenticated both peer keys and exchanged 256 useful bytes in each direction without resumption. This is sufficient for the documented passive recorded-traffic confidentiality construction in K01, within the assumptions of X25519/ML-KEM and TLS 1.3.

Assessment method

Versioned configuration selection, source mapping and positive/negative execution

Source context

Pinned public libp2p/Go source plus local five-case QUIC/TLS component execution, 2026-10-22

Outstanding qualification

Configuration-specific Yes, not a claim about every libp2p build or peer. The control run with a classical-only server succeeded using X25519 (29), proving that defaults do permit classical fallback. A component configuration limiting CurvePreferences to group 4588 succeeded against the hybrid peer and failed against the classical peer; this custom TLS configuration is not presented as a stock libp2p host CLI option. A wrong expected Peer ID also failed. Execution covers loopback IPv4/UDP/QUIC and the official libp2p TLS identity component, not a complete libp2p host, Identify, ConnectionGater revocation, migration or independent interoperability. Native QUIC transport source uses the same Identity.ConfigForPeer path without overriding the TLS group list; applicability to that path is a source inference. The matrix explicitly selects the versioned hybrid negotiation case. Peer ID and certificate signatures remain classical: no post-quantum active-attacker authentication, independent cryptographic audit or deployment guarantee. No extension of the F25 byte witness to this execution is inferred.

Public sources

Editorial evidence references

The following identifiers refer to research records not included in this public package; they are not public links.