96 lines
4.1 KiB
Markdown
96 lines
4.1 KiB
Markdown
# Tick 22 — 2026-05-22 08:17 UTC
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**Thread:** ADR-107 (cross-installation federation with secure aggregation)
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**Verdict:** Closes the privacy + federation chain explicitly deferred from ADR-105 + ADR-106. The full chain R6 → R3 → R14 → R15 → ADR-105 → ADR-106 → ADR-107 now has a formal guarantee at every layer.
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## What shipped
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- `docs/adr/ADR-107-cross-installation-federation.md` — full ADR draft. Direct extension of ADR-105 + ADR-106.
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## Five-layer defence (extends ADR-106's three)
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| Layer | Mechanism | Defends against |
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|---|---|---|
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| 1–3 (ADR-106) | Primitive isolation + grad clipping + DP noise | Local member inference, biometric exfiltration |
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| **4 NEW** | Secure Aggregation (Bonawitz 2016) | Cross-installation aggregator sees only sum |
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| **5 NEW** | Per-installation embedding-space rotation key | Cross-installation re-identification (R3 binding) |
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## Counter-intuitive privacy win
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With N installations each at σ_local = 1.0:
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- Per-installation ε after 50 rounds: 2.5
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- **Cross-installation effective σ = √N · σ_local ≈ 3.16** (amplification by sampling)
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- **Cross-installation ε after 50 rounds: ~1.5** — STRONGER than per-installation alone
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**Cross-installation federation actually IMPROVES privacy** through the amplification effect, as long as the cryptographic protocol is implemented correctly.
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## Bandwidth
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Per round, 10 installations: ~2 MB/installation. Monthly cadence: 70-200 MB/month/installation total (within + cross-installation). <0.1% of home broadband.
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## Implementation budget
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Additive on prior ADRs:
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| ADR | LOC |
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|---|---:|
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| ADR-105 (federation) | 500 |
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| ADR-106 (DP-SGD + isolation) | +300 |
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| **ADR-107 (cross-installation)** | **+530** |
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| **Total `ruview-fed` budget** | **~1,330 LOC, ~6 weeks** |
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## Why this closes the chain
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The research loop has produced 7 layers, each with a formal guarantee:
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1. **R6 / R6.1** — physics forward model
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2. **R3** — embedding-space re-ID
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3. **R14** — ethical opt-in / on-device / override
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4. **R15** — biometric primitive catalogue
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5. **ADR-105** — within-installation federation
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6. **ADR-106** — DP-SGD + primitive isolation
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7. **ADR-107** — cross-installation + secure aggregation
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**No remaining unspecified privacy gap.** Cross-installation training can ship without violating any constraint surfaced by the loop.
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## Threat model (8 threats, 8 layers)
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Every threat row has a mitigation layer. Member inference (cross-installation) → Layer 3 + cross-installation DP composition. Cross-installation re-ID → Layer 5 rotation key. Sybil → Layer 4 dropout + Krum + N ≥ 5.
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Quantum-resistant DH = out-of-scope future ADR-108; Kyber substitution is mechanical.
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## Composes with everything
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- R3 + R15 enforcement now technical, not just policy
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- R7 mincut extends to cross-installation multi-installation adversarial detection
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- R12 PABS works at any installation in the local rotated embedding space
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- R10/R11 cogs benefit asymmetrically; `cog-wildlife` is high-value cross-installation, `cog-maritime-watch` is per-vessel
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## Honest scope
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- Cross-org PKI bootstrapping = operational, not architectural
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- Implementation cost real: 1,330 LOC + 6 weeks engineering
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- Krum + SA composition proof is non-trivial; reference implementations needed
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- √N amplification assumes installation independence (correlated installations need separate accounting)
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- Drop-out reconstruction has known attack surfaces; follow Bonawitz §4.3 carefully
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- Per-cog suitability varies; not all cogs benefit equally
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## Coordination
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`ticks/tick-22.md`. No PROGRESS.md edit. Branch `research/sota-adr107-cross-install-federation`.
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## Remaining work
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- **R6.2.3**: chest-centric / pose-trajectory zones
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- **R6.2.2.1**: 3D N-anchor coverage
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- **R12.1**: pose-PABS closed loop (highest-leverage implementation)
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- **R3.2**: embedding-level physics-informed env (R3.1's corrected sketch)
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- **ADR-108**: quantum-resistant DH substitution (Kyber)
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~3.6h to cron stop. **22 ticks landed.** The loop has covered:
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- 13 research threads (R1-R15)
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- 3 ADRs (105, 106, 107) closing the privacy + federation chain
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- 3 kinds of negative result (physics-floor, architecture-error, revisited-to-positive)
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- 7 deferred follow-ups closed
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