Closes the cryptographic-attestation gap in ADR-116 §2.2: every
witness event can now be signed by the Seed's Ed25519 key, with
verify available to any auditor holding the public key.
Module shape (`src/witness_signing.rs`, kept separate from
`witness::` so the hash chain stays usable without dalek linked
in — important for the wasm32 audit-verifier variant we'll ship
later):
* sign_event(event, &SigningKey) -> Signature
* verify_signature(event, &Signature, &VerifyingKey)
-> Result<(), SignatureVerifyError>
* signature_to_hex / signature_from_hex (128-char lowercase,
matches the witness hex convention)
* SignatureVerifyError::Invalid
* SignatureParseError::{Length, Hex}
Key design point: signature covers the SAME canonical bytes
witness::hash_event hashes. That means:
1. A signed event commits to the entire event content (kind,
payload, timestamp, seq, prev_hash) — no field can be
retroactively changed without invalidating both the hash AND
the signature.
2. The signature implicitly commits to the event's *chain
position* via prev_hash — splicing a signed event into a
different chain breaks verification.
Adds `ed25519-dalek = "2.1"` to cog-ha-matter (already in
workspace via ruv-neural, version kept aligned).
9 new tests:
* sign_and_verify_round_trip
* verify_rejects_signature_under_wrong_key
* verify_rejects_tampered_event (mutate payload after sign)
* verify_rejects_event_with_wrong_prev_hash (splice attack)
* signature_hex_round_trip
* signature_from_hex_rejects_wrong_length
* signature_from_hex_rejects_non_hex
* signature_is_deterministic_for_same_event_and_key
(locks Ed25519's determinism — catches future accidental
swap to a randomized scheme)
* different_events_produce_different_signatures
60/60 cog tests green (51 → 60). Key management is intentionally
out of scope here — the cog runtime reads the Seed's key from the
Cognitum control plane's secure store (separate concern).
ADR-116 P4 now ⁵⁄₆: ✅ mDNS record, ✅ chain, ✅ JSONL, ✅ file
persistence, ✅ Ed25519 signing; ⏳ responder + embedded broker.
Co-Authored-By: claude-flow <ruv@ruv.net>
Second P4 unit: an append-only SHA-256 hash chain for tamper-evident
audit logging. ADR-116 §2.2 promised this for healthcare /
education / shared-housing deployments — this lands the primitive
with no key dependency so the next iter can layer Ed25519 signing
on top without touching the chain itself.
Module shape:
* `WitnessHash([u8; 32])` newtype + `WitnessHash::GENESIS` sentinel
* `WitnessEvent { seq, prev_hash, ts, kind, payload, this_hash }`
— once committed, every field is immutable
* `WitnessChain` — `append`, `tip`, `verify`, `events`
* `canonical_bytes` — length-prefixed serialization that prevents
the classic concatenation forgery
(`abc|def` ≠ `ab|cdef`)
* `WitnessVerifyError` — auditor-friendly error with `at: usize`
on every variant (SeqGap, PrevHashMismatch, HashMismatch)
13 new tests covering both happy path and active tampering:
* genesis hash all-zeros
* empty chain tip is genesis
* canonical bytes length-prefixed (anti-forgery)
* canonical bytes start with prev_hash (wire-format lock)
* append links to prev_hash
* seq monotonic from 0
* verify passes on clean chain
* verify catches tampered payload (fires HashMismatch)
* verify catches broken prev_hash link
* verify catches seq gap
* hash hex is 64 lowercase chars
* first event prev_hash == GENESIS (auditor anchor)
* different payloads → different hashes
Hash-chain over Merkle is the right tradeoff for the cog's event
rate (a few/min steady, dozens during a fall) — linear scan is
fine and we save the Merkle complexity for a future tier when
chains span days.
34/34 cog tests green (21 → 34).
ADR-116 P4 row updated to enumerate the three P4 sub-units shipped /
pending: (a) mDNS record-builder ✅, (b) witness hash-chain ✅, (c)
responder + embedded broker + Ed25519 signing pending.
Co-Authored-By: claude-flow <ruv@ruv.net>
Opens P4 with the smallest extractable unit: a pure builder that
produces the wire-format `MdnsService` the responder will publish
next iter. Splitting the record-builder from the responder lets
us:
* lock the TXT-record surface with named unit tests so drift
between the cog and the HA-side YAML auto-discovery binding
fires a test instead of silently breaking deployments,
* swap the responder library (mdns-sd / zeroconf / pnet) without
touching content,
* include the advertisement in `--print-manifest` for Seed
integration tests that can't boot tokio.
TXT surface (sorted, RFC 6763):
| cog_id | "ha-matter" |
| cog_version | CARGO_PKG_VERSION |
| node_id | identity.node_id |
| mqtt_port | u16 stringified |
| privacy | "1" | "0" |
| proto | "ruview-ha/1" |
9 new tests:
* service_type locked to `_ruview-ha._tcp`
* instance_name carries node_id
* control_port advertises the *control plane*, not MQTT
* privacy flag is "1"/"0" (HA config flow reads it byte-stable)
* proto version locked to ruview-ha/1 (bump is deliberate)
* cog_id in TXT matches crate constant
* txt_records sorted for byte-stable mDNS responses
* **PII leak guard**: TXT must NOT carry hr_bpm, br_bpm, pose_*,
keypoint, ssid, lat, lon, mac, rssi — broadcasts in cleartext
so a future "let's add hr_bpm for convenience" patch fires
here, not in a privacy incident.
* required-keys lock — adding is fine, removing/renaming breaks
every deployed Seed.
21/21 cog tests green (12 → 21).
ADR-116 P4 flipped pending → in progress, with the responder /
embedded broker / witness chain enumerated as the remaining P4
sub-units.
Co-Authored-By: claude-flow <ruv@ruv.net>
Adds `runtime::build_publisher_inputs(host, port, privacy, identity)` —
the side-effect-free helper that turns the cog's CLI surface into the
`(MqttConfig, OwnedDiscoveryBuilder)` pair ADR-115's `publisher::spawn`
consumes. Keeps the tokio runtime wiring out of the pure unit so the
mDNS responder + Seed control plane (P4) can build the same inputs
from different sources without going through clap.
8 new tests lock the wire-format invariants:
* host/port round-trip into MqttConfig
* privacy_mode propagation (P1 dossier item 7, FDA Jan 2026)
* discovery_prefix defaults to "homeassistant"
* discovery carries node_id + sw_version + friendly_name
* via_device advertises COG_ID (ADR-101/102 device-registry shape)
* client_id includes node_id (lesson from ADR-115 iter 45-48 session
takeover post-mortem — two publishers sharing a client_id loop)
* tls defaults to Off for v1 LAN-only (lock against silent enablement)
* default_identity carries CARGO_PKG_VERSION + PID for uniqueness
Plus the existing 2 manifest tests → 10/10 green
(`cargo test -p cog-ha-matter --no-default-features --lib`).
Also lands the deep-researcher dossier (`docs/research/ADR-116-ha-...`)
that the ADR §3+§4 reference — it was produced last iter but only the
ADR was committed; this puts the source-of-truth into the tree so the
ADR's "8 sections, 30+ citations" claim is actually verifiable.
P3 status in the ADR phase table flipped from "pending" to "in progress"
with the helper named; next iter tokio::spawns publisher::run(...) in
main.rs and registers the mDNS responder.
Co-Authored-By: claude-flow <ruv@ruv.net>
ruv