Secure paths for
shared history
Proofs are only as reachable as the network that carries them. Astrea gives validators authenticated sessions, separate traffic lanes, replay protection, and explicit resource limits — the network moves proposals and evidence, while consensus alone decides what becomes authoritative.
A session begins with identity
A validator connection works like a secure workroom with a checked guest list. Both sides establish who they are, which network epoch they belong to, and which keys protect the session before protocol traffic enters.
A validator identity is admitted under the current committee and epoch rules. The handshake binds that identity to the negotiated session, derives fresh traffic keys, and records the limits both peers must follow. A packet from an authenticated connection still has to pass frame, replay, epoch, and protocol validation.
Astrea carries a classical and a post-quantum companion through each applicable network boundary, with different primitives doing different jobs. X25519 and ML-KEM-768 establish the two halves of a hybrid secret for validator sessions, PRISM onion hops, and Dandelion# stem layers. Each side of a validator handshake authenticates its transcript-bound message with secp256k1 Schnorr and ML-DSA-65. PRISM frames instead use secp256k1 ECDSA and ML-DSA-65 over the same canonical frame bytes. Both companions are mandatory and are combined or verified as appropriate; the post-quantum side is not an optional fallback. In Dandelion#, the hybrid secret protects the forwarding layer; the canonical transaction is meant to become public when diffusion broadens.
For validator sessions, those fresh combined secrets produce directional traffic keys. Retiring old session keys provides forward secrecy across sessions: a later key compromise does not automatically unlock earlier captured traffic. An attacker controlling an endpoint can still see the data and keys available during that compromise, so endpoint security remains its own boundary.
Establish the secret X25519 + ML-KEM-768
X25519 supplies the classical key-agreement half; ML-KEM-768 supplies the post-quantum half. Astrea binds both into validator-session, PRISM onion-hop, and Dandelion# stem-layer secrets.
Authenticate the message Schnorr / ECDSA + ML-DSA-65
Validator handshakes pair secp256k1 Schnorr with ML-DSA-65 on a transcript-bound message. PRISM frames pair secp256k1 ECDSA with ML-DSA-65 on the same canonical frame bytes. A missing or invalid required companion rejects the applicable handshake message/session or PRISM frame.
Admit
Check the peer identity and its authority for the current epoch.
Combine
Require both signature companions over each transcript-bound handshake message.
Derive
Create fresh directional keys for authenticated encryption.
Separate
Move traffic through lanes with their own budgets and rules.
Astrea is engineered for 160-bit post-quantum security in its primary profile, and no supported profile falls below an absolute 128-bit post-quantum floor. That posture is conditional on the declared constructions, parameters, assumptions, implementation, and deployment boundary. Network metadata, endpoint security, and surrounding software remain separately scoped.
Urgent work keeps a clear path
Votes and repair requests use queues separate from large transfers. Astrea divides traffic by purpose, then applies limits where contention actually occurs.
Time-sensitive proposals, votes, and commit evidence use the validator path with the strictest admission policy.
Missing parents and bounded catch-up data can be requested without turning repair into authority.
Larger authenticated bodies and proof material travel outside the consensus hot path under separate limits.
A full bounded queue slows or rejects new work before it can consume every buffer.
Backpressure means a receiver slows or rejects new work when a bounded queue is full. Per-peer, per-lane, and per-frame limits keep one source from consuming every buffer. These controls contain resource pressure and make overload behavior predictable. A public node can still face a flood; admission and backpressure bound the work it accepts.
The private edge has lanes of its own. PRISM carries an agent's privacy-sensitive traffic on a route separate from the authenticated validator and core lanes, and that route does not depend on which chain the traffic concerns: a shielded deposit bound for the bridge, an action bound for an Ethereum venue, and a withdrawal bound for Zcash travel the same shaped lanes, with cover traffic, size classes, and release jitter applied to each. The privacy page states what that route reduces and what it leaves visible.
Every object earns acceptance
Authentication identifies who sent the bytes. Consensus validation determines whether those bytes may affect authoritative history. Astrea gives each decision its own boundary.
Open the authenticated frame
The receiver checks the session, traffic direction, sequence state, size, and authentication tag.
Decode one canonical object
Canonical encoding prevents two byte representations from quietly meaning the same protocol object.
Apply protocol validation
The node checks epoch, authorship, parents, signatures, and the rules for that object type.
Accept or stage
A valid object is durably accepted when its requirements are present. An object with a missing parent can wait in a bounded staging path while repair runs.
A compromised courier can deliver a forged document. Official status still comes from the authority check. Astrea treats the network as the courier and the consensus rules as that check.
Repair returns a node to the decided history
A recovering node uses bounded retry, deduplication, missing-parent repair, and checkpoint-based catch-up to retrieve the evidence it needs after a disconnect or restart. Replaying a valid object cannot give it a second vote, and repairing an old parent cannot rewrite the committed prefix.
Notice a parent is missing
The object waits in bounded staging instead of entering accepted history.
Ask through repair
A dedicated lane retrieves the named dependency under its own budget.
Check the returned object
Authentication and protocol rules still decide whether the parent is accepted.
Resume from known history
The node advances from its checkpoint without rewriting the committed prefix.
Operators can observe queue pressure, rejected frames, reconnects, and repair demand without placing those measurements inside consensus. This keeps operational insight useful and keeps monitoring systems from becoming a source of truth.
Encrypted transport protects content on the connection. Peers and network observers can still learn facts from endpoints, timing, size, and traffic shape. The privacy guide explains those metadata boundaries and the separate routing layer.