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Wovyr

ADR-0009: Wovyr-Native Keyless Signing (Sigstore-Shaped, Offline-Verifiable)

Status: Accepted Date: 2026-07-03 Deciders: Platform Security Team Supersedes: — (complements the ed25519 TrustStore mode, which remains)

Context

Section titled “Context”

Plugin packages are signed with long-lived publisher ed25519 keys verified against a TrustStore (wovyr-plugin/src/verify.rs). Long-lived keys are the supply chain’s weakest link: they leak, they outlive the people who held them, and revocation is manual. The v0.3 security track calls for keyless (identity-based) signing in the Sigstore style: a certificate authority (Fulcio’s role) binds an OIDC identity to a short-lived certificate over an ephemeral key; a transparency log (Rekor’s role) publicly witnesses each signing event; verifiers trust a pinned root, not per-publisher keys.

Adopting the real Sigstore stack wholesale conflicts with this codebase’s constraints:

  • Determinism ([coding-standards §7]): core logic takes no ambient clock or network. Sigstore verification libraries fetch TUF roots and check X.509 validity against wall clock.
  • Offline-first development: the public fulcio/rekor.sigstore.dev are not reachable from CI or the dev environment reliably; X.509/Fulcio parsing pulls a heavy dependency tree.
  • The platform already has the primitives the design needs: ed25519 sign/verify (ring), a hash-chained tamper-evident audit log (wovyr-audit), and the capability-gated live-test pattern for real infrastructure.

Decision

Section titled “Decision”

Implement Wovyr-native keyless signing in wovyr-plugin/src/keyless.rs: the Sigstore architecture (ephemeral key → short-lived identity certificate → transparency-log witness → pinned-root verification) with Wovyr-native encodings (canonical delimiter-separated byte strings signed by ed25519, JSON on the wire) instead of X.509/DER.

  1. Ports, not services. CertificateAuthority and TransparencyLog are traits. InMemoryCa/InMemoryTransparencyLog are the deterministic in-process implementations (tests, single-operator dev). A Rekor-backed log (rekor.rs, rekor cargo feature) appends rekord entries to a real Rekor server; deployment/rekor/ runs one locally (pinned release images, no source builds), live-tested behind WOVYR_REKOR_URL (tests/rekor_live.rs).
  2. Verification is fully offline and clock-free. A KeylessBundle (certificate + manifest signature + log entry) is self-contained; verifiers hold a pinned KeylessRoot (CA + optional log public keys). The certificate-validity check anchors on the log’s integrated_time, never a local clock, so verify_keyless is deterministic over its inputs. Certificates are backdated by a 60 s skew allowance (Rekor timestamps are whole seconds).
  3. Identity → namespace binding, fail-closed. An IdentityPolicy maps identities (issuer exact, subject prefix-wildcard) to the publisher namespaces they may sign for, checked against the manifest’s declared publisher — an allowed identity cannot sign for someone else’s namespace. Empty policy admits nobody. A transparency-log entry is required unless the operator opts out (require_transparency: false, the registry-witnessed mode).
  4. Bundles ride in the .wovyrpkg envelope (optional keyless field), and Package::verify_keyless(root, policy) is the counterpart to the existing Package::verify(trust). Both trust modes coexist; consumers choose per policy.

Consequences

Section titled “Consequences”
  • (+) Verification needs zero network and no new dependencies; the full matrix (tamper, unpinned CA, policy denial, expired window, forged SET, missing entry) is unit-tested offline; the Rekor path is proven live against real infrastructure.
  • (+) Publishers need no long-lived signing secret; compromise windows shrink to the certificate TTL (default 10 min).
  • (−) Not wire-compatible with Sigstore tooling (cosign cannot verify an Wovyr bundle). Acceptable: the trust root is operator-pinned either way, and the architecture leaves room to swap encodings later.
  • (+) Rekor’s signed entry timestamp is verified offline: the bundle carries Rekor’s canonicalized entry body, the verifier reproduces the RFC 8785 SET payload ({body, integratedTime, logID, logIndex}), and pinned log keys are accepted as raw/SPKI ed25519 or ECDSA P-256 (Rekor’s memory signer) — proven live against a real Rekor (forged coordinates are rejected).
  • (−) No real OIDC yet: the CA attests whatever identity the operator of the signing environment asserts. Fine for the dev CA; a Fulcio-compatible or OIDC-validating CA is additive behind the same trait.

Consumers (landed after the core)

Section titled “Consumers (landed after the core)”

Keyless is a policy-selectable trust mode at both supply-chain choke points, with identical no-downgrade semantics (a present bundle is verified keylessly or rejected — never falls back to the publisher-key path):

  • Registry publish — Registry::with_keyless(root, policy) (wovyr-marketplace); a keyless-only package flows publish → discover → download → install → enable with no publisher key anywhere (tests/keyless_supply_chain.rs).

  • Engine install — PluginEngine::with_keyless(root, policy) (wovyr-plugin).

  • Server — both are configured from one operator file, ~/.wovyr/plugins/keyless.json ({"root": …, "policy": …}); absent ⇒ keyless disabled.

  • CLI tooling — wovyr plugin keyless-init (dev CA + pinned trust config, shared with the server) and wovyr plugin keyless-sign (ephemeral key never touches disk; --rekor <url> witnesses the signing, behind the CLI’s keyless-rekor feature). plugin.keyless.json beside a manifest rides into packages via pack/install/publish, and plugin.sig becomes optional for keyless-only packages.

Deferred

Section titled “Deferred”
  • Merkle inclusion-proof checks against the log’s signed tree head.
  • X.509/Fulcio certificate compatibility; OIDC token validation in the CA (a non-goal while the trust root is operator-pinned — revisit if cosign interop is ever required).
  • Audit-log recording of keyless publish events.