feat(broker): invite signature verification + atomic one-time-use
Completes the v0.1.0 security model. Every /join is now gated by a
signed invite that the broker re-verifies against the mesh owner's
ed25519 pubkey, plus an atomic single-use counter.
schema (migrations/0001_demonic_karnak.sql):
- mesh.mesh.owner_pubkey: ed25519 hex of the invite signer
- mesh.invite.token_bytes: canonical signed bytes (for re-verification)
Both nullable; required for new meshes going forward.
canonical invite format (signed bytes):
`${v}|${mesh_id}|${mesh_slug}|${broker_url}|${expires_at}|
${mesh_root_key}|${role}|${owner_pubkey}`
wire format — invite payload in ic://join/<base64url(JSON)> now has:
owner_pubkey: "<64 hex>"
signature: "<128 hex>"
broker joinMesh() (apps/broker/src/broker.ts):
1. verify ed25519 signature over canonical bytes using payload's
owner_pubkey → else invite_bad_signature
2. load mesh, ensure mesh.owner_pubkey matches payload's owner_pubkey
→ else invite_owner_mismatch (prevents a malicious admin from
substituting their own owner key)
3. load invite row by token, verify mesh_id matches → else
invite_mesh_mismatch
4. expiry check → else invite_expired
5. revoked check → else invite_revoked
6. idempotency: if pubkey is already a member, return existing id
WITHOUT burning an invite use
7. atomic CAS: UPDATE used_count = used_count + 1 WHERE used_count <
max_uses → if 0 rows affected, return invite_exhausted
8. insert member with role from payload
cli side:
- apps/cli/src/invite/parse.ts: zod-validated owner_pubkey + signature
fields; client verifies signature immediately and rejects tampered
links (fail-fast before even touching the broker)
- buildSignedInvite() helper: owners sign invites client-side
- enrollWithBroker sends {invite_token, invite_payload, peer_pubkey,
display_name} (was: {mesh_id, peer_pubkey, display_name, role})
- parseInviteLink is now async (libsodium ready + verify)
seed-test-mesh.ts generates an owner keypair, sets mesh.owner_pubkey,
builds + signs an invite, stores the invite row, emits ownerPubkey +
ownerSecretKey + inviteToken + inviteLink in the output JSON.
tests — invite-signature.test.ts (9 new):
- valid signed invite → join succeeds
- tampered payload → invite_bad_signature
- signer not the mesh owner → invite_owner_mismatch
- expired invite → invite_expired
- revoked invite → invite_revoked
- exhausted (maxUses=2, 3rd join) → invite_exhausted
- idempotent re-join doesn't burn a use
- atomic single-use: 5 concurrent joins → exactly 1 success, 4 exhausted
- mesh_id payload vs DB row mismatch → invite_mesh_mismatch
verified live: tampered link blocked client-side with a clear error.
Unmodified link joins cleanly end-to-end (roundtrip.ts + join-roundtrip.ts
both pass). 64/64 tests green.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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