Peers are authenticated at the connection layer via libp2p TLS 1.3 (peerIdFromVerifiedCertificate): self-signed X.509 validity, libp2p extension OID in TBSCertificate [3] EXPLICIT Extensions, and SignedKey signature over libp2p-tls-handshake: || SPKI.

QuicOutboundDialOptions always verifies the server leaf after connect. Do not use peerIdFromCertificateUnverified on untrusted certificates.

Lean and Eth2 consensus use gossipsub StrictNoSign: Message publishes omit from, seqno, and signature. zig-libp2p:

• Derives message_id as truncated SHA-256 over (domain, topic, data) (see gossipsub/message_id.zig).
• Suppresses duplicates via duplicate_cache.
• Does not authenticate data at the gossipsub layer.

Application responsibility: after SSZ-decoding block/attestation payloads, run consensus state_transition / signature checks. Wire an optional GossipsubConfig.topic_validator to drop invalid blobs early.

TLS peer id ≠ message author under StrictNoSign; only the transport peer is cryptographically bound.

listen_addrs in Identify are hints. When signed_peer_record (RFC 0002) is present, identify.verifySignedPeerRecord / inbound handlers verify the envelope before invoking callbacks.

Unsigned listen addresses must not be dialed without independent validation.

See issues #119–#127 for the audit that introduced these policies.