# vsa attestor

Source: https://www.testifysec.com/docs/cilock/attestors/vsa

Typed decoder for pre-signed SLSA VSA predicates so downstream policies can consume external VSAs as first-class attestations — distinct from policyverify, which produces a VSA at verify time.

Typed decoder for pre-signed SLSA VSA predicates so downstream policies can consume external VSAs as first-class attestations — distinct from [`policyverify`](https://www.testifysec.com/docs/cilock/attestors/policyverify), which *produces* a VSA at verify time.

 

| Field | Value |
| --- | --- |
| Name | `vsa` |
| Predicate type | `https://slsa.dev/verification_summary/v1` |
| Lifecycle | `verify` |
| Default binary? | **No** — builder opt-in only |

 

## What it captures

 

The attestor wraps a `VerificationSummary` predicate that mirrors the SLSA VSA v1 shape. Its `MarshalJSON` emits the embedded predicate directly so Rego sees `input.verifier.id`, `input.verificationResult`, etc.

 

Fields on `VerificationSummary`:

 

- `verifier` — `{ id string }` identifying the party that ran verification.
 - `timeVerified` — wall-clock timestamp the source VSA was produced.
 - `policy` — `ResourceDescriptor` (`uri`, `digest`) referencing the policy that was evaluated.
 - `inputAttestations[]` — `ResourceDescriptor` entries (`uri`, `digest`) for each attestation considered.
 - `verificationResult` — `"PASSED"` or `"FAILED"` (the only two values defined in the package).

 

`ResourceDescriptor` shape: `{ uri string, digest cryptoutil.DigestSet }`.

 

## When to use

 

Build this attestor in when a downstream policy needs to read a VSA that was produced *outside* the current pipeline — for example, a deploy gate that ingests a release pipeline's signed VSA as an external attestation, then re-asserts policy on top of it. The factory is looked up via `FactoryByType` on the predicate URI and decodes the bare DSSE payload into the typed shape.

 

Contrast with [`policyverify`](https://www.testifysec.com/docs/cilock/attestors/policyverify): `policyverify` runs inside `cilock verify` and *emits* a fresh VSA recording the outcome of that verify run. `vsa` does the inverse — it has a no-op `Attest()` and exists purely so a pre-signed VSA predicate can be unmarshalled and exposed to Rego under canonical SLSA field names.

 

## Flags

 

None. The attestor has no flag surface; it is selected by predicate-type lookup, not by name on the CLI.

 

## Output shape

 

```json
{
  "verifier": { "id": "..." },
  "timeVerified": "2026-05-21T12:34:56Z",
  "policy": {
    "uri": "...",
    "digest": { "sha256": "..." }
  },
  "inputAttestations": [
    { "uri": "...", "digest": { "sha256": "..." } }
  ],
  "verificationResult": "PASSED"
}
```

 

## Gotchas

 

- **Verify-only.** `RunType` is `attestation.VerifyRunType`. The factory is not selectable inside `cilock run` and `Attest()` is a no-op — it never produces an attestation by itself.
 - **Decoder, not emitter.** To emit a VSA from a verify run, use [`policyverify`](https://www.testifysec.com/docs/cilock/attestors/policyverify). The `vsa` package exists so external VSAs can flow into downstream policies as typed input.
 - **PredicateType is the only routing key.** Registration uses the SLSA VSA v1 URI; bare-predicate DSSEs with any other type will not be routed to this factory.
 - **Field names match the SLSA spec, not the wrapper.** Custom `MarshalJSON`/`UnmarshalJSON` flatten the embedded `Predicate` field out of the JSON, so policies should reference `verifier`, `verificationResult`, etc. directly — not `predicate.verifier`.

 

## CLI example

 

See the constraint summary + reproduction recipe at [https://github.com/aflock-ai/attestor-compliance-examples/tree/main/42-vsa](https://github.com/aflock-ai/attestor-compliance-examples/tree/main/42-vsa). This attestor is currently blocked or doc-only — the linked example explains why and shows the recipe to validate once the constraint is removed.

 

## See also

 

- [Catalog row](https://www.testifysec.com/docs/cilock/reference/attestor-catalog)
 - [Build from source](https://www.testifysec.com/docs/cilock/getting-started/installation#build-from-source)
 - [`policyverify`](https://www.testifysec.com/docs/cilock/attestors/policyverify) — the verify-time VSA emitter
 - [SLSA VSA spec](https://slsa.dev/spec/v1.0/verification_summary)

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