CS1 — Investigative Media Provenance

Setting. A newsroom publishes sensitive images and articles that must retain provenance across syndication and archival.

Design

Embed the EP JSON as a C2PA assertion; anchor daily on ETH finalized and weekly on BTC archival; require KBA (domain) and a witness cosign by the editor-in-chief; transformation receipts for cropping/toning with invariants for EXIF timestamps.

Policy Profile

CFS‑Dual (θ=0.98); min_watchers=2; DAVS≥0.75; category=sensitive; PQ‑hybrid signatures for new EPs.

Workflow

Capture raw asset → generate EP (EL‑C14N‑v2, EL‑RM2) → Dual anchors → C2PA embedding → publish.
Syndication copies carry the same EP assertion; verifiers check EP offline and C2PA manifest in viewers.

Evidence & Verification

Verifiers recompute the authoritative digest; validate signatures and EP context; evaluate anchors and predicates; parse the transformation receipt to ensure semantics were preserved (coverage ≥ 0.85).

Cost & Operations

Batch-per-day anchoring amortizes fees; replicas at 3 institutions with 24‑month retention; catalog index for discovery.

Outcomes

Provenance remains intact offline; retractions use tombstones with replacements; third parties can audit timing without network.

Risks & Mitigations

Human error in labeling → mitigated by Safety Declarations and witness review; paraphrase attempts → VCE‑v2 thresholds; anchor censorship → watcher diversity.

KPIs

≥99.9% cryptographic acceptance; ≥95% assets with ETH+BTC anchors; DAVS median ≥0.8; zero unresolved tombstones.