Tracking: Signing & Trust v1

[michael-herwig]

Goal

Secure defaults for OCX packages: publisher signs after push, consumer verifies by default, typosquat defeated.

1. Sign + verify via keyless Sigstore — real pipeline over the PR feat(cli,oci): OCI referrers sign + verify (slice 1) #87 scaffold (ocx package sign / ocx package verify; sigstore-rs, Rekor v1 + TUF-distributed trust root).
2. Registry capability handling — OCI 1.1 Referrers API detection, clean actionable error, no tag fallback.
3. Identity-pinned verify via [trust.policy] in ocx.toml — defeats typosquatting.
4. Offline / air-gapped trust-root story — trust-root cache, OCX_OFFLINE semantics, OCX_SIGSTORE_TUF_ROOT override.
5. Auto-verify on install / pull (policy-gated) — promotion from "command exists" to "default secure".
6. cosign v3 interop — cosign 3.x reads OCX signatures and vice versa.

Sub-issues

Dependency order (#195 runs parallel to the #194 spike):

• PR feat(cli,oci): OCI referrers sign + verify (slice 1) #87 — OCI referrers sign + verify (slice 1) — merge
• Acceptance harness: referrers-capable registry (registry:3 or zot) #195 — Test infra: referrers-capable registry (registry:3/zot; keep one registry:2 as permanent ReferrersUnsupported negative fixture)
• Implement sign/verify pipeline via sigstore-rs (slice 2) #194 — Implement sign/verify pipeline via sigstore-rs (slice 2) — critical path
• Wire referrers capability cache into sign/verify pipelines (clean error, no tag fallback) #106 — Wire referrers capability cache into sign/verify pipelines
• Identity-pinned verify: [trust.policy] in ocx.toml #98 — Identity-pinned verify ([trust.policy])
• Offline and air-gapped verify: trust-root cache + refresh #196 — Offline/air-gapped verify + trust-root cache
• Auto-verify on ocx install / ocx pull (policy-gated) #99 — Auto-verify on ocx install / ocx pull (policy-gated)
• Rekor v2 migration delta (gated on #194 spike) #107 — sigstore-rs Rekor v2 delta (gated on Implement sign/verify pipeline via sigstore-rs (slice 2) #194 spike outcome)
• cosign v3 interop suite #197 — cosign v3 interop suite (last)

External (pending, not milestone-gated):

• Mirror tool: re-sign + attest bundles #105 — Mirror re-sign + attest — closed, migrated to feat(pipeline): re-sign + attest mirrored bundles ([sign]/[provenance] spec block) ocx-mirror#7. This milestone unblocks ocx-mirror#7: the mirror is a downstream consumer of the Implement sign/verify pipeline via sigstore-rs (slice 2) #194 pipeline.

Threat coverage (post-milestone)

Threat	Defense	Issue
Compromised registry	OCI Referrers API + Sigstore verify	#194
Typosquatting	Identity pinning in [trust.policy]	#98
Mirror-bundle tampering	Mirror re-sign + attest (pending, external)	#105 (closed) → ocx-sh/ocx-mirror#7

SBOM, SLSA provenance, and OSV scanning moved to milestone B — tracker #199.

Non-goals (deferred)

• ocx package push --sign (sign-on-push) — v1 flow is sign after push as a separate step; a combined flag is explicitly deferred.
• cosign pre-3.0 consumer compat — dropped. Floor is cosign >= 3.0 (referrers-mode default, .sig tags deprecated upstream). OCX is referrers-only; never add a tag-schema fallback. Document the floor in the user guide / threat model.
• Notation parallel implementation (cosign-only in v1).
• PKCS#11 / YubiKey signing UX (keyless OIDC covers public OCX.sh; hardware keys are enterprise v2 concern).
• Private TUF trust root (use Sigstore's TUF-distributed root in v1; bring-your-own-TUF deferred).
• Reproducible-builds rebuilder integration.
• SLSA VSA (Verification Summary Attestation).

Test fixtures

All acceptance tests reuse the fake Fulcio + Rekor + OIDC stack from PR #87 (test/tests/fixtures/fake_sigstore.py). Fixture extensions kept minimal — reuse over duplication.

Done when

• All sub-issues closed; PR feat(cli,oci): OCI referrers sign + verify (slice 1) #87 merged.
• Auto-verify is default-on for policy-scoped packages.
• Website sign/verify cast recorded.
• task verify green.