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Typed SLSA Provenance predicates for PHP, both the current v1 and the legacy v0.2 that most real-world bundles still carry. Built on in-toto attestations.

SLSA Provenance describes how an artifact was built — the build definition (inputs) and the run details (who built it, when, and what came out). This package models that predicate as typed value objects and plugs it straight into an in-toto Statement, ready to sign with k2gl/dsse.

Install

composer require k2gl/slsa-provenance

Requires PHP 8.1+. Pulls in k2gl/in-toto-attestation and k2gl/dsse.

Usage

use K2gl\Slsa\Provenance;
use K2gl\Slsa\BuildDefinition;
use K2gl\Slsa\RunDetails;
use K2gl\Slsa\Builder;
use K2gl\Slsa\BuildMetadata;
use K2gl\InToto\ResourceDescriptor;

$provenance = new Provenance(
    new BuildDefinition(
        buildType: 'https://example.com/buildtypes/v1',
        externalParameters: ['repository' => 'https://github.com/k2gl/dsse', 'ref' => 'refs/tags/1.0.0'],
        resolvedDependencies: [
            new ResourceDescriptor(uri: 'git+https://github.com/k2gl/dsse', digest: ['gitCommit' => '…']),
        ],
    ),
    new RunDetails(
        builder: new Builder(id: 'https://github.com/actions/runner', version: ['runner' => '2.x']),
        metadata: new BuildMetadata(invocationId: 'run-42', startedOn: '2026-05-30T00:00:00Z'),
    ),
);

// Wrap as an in-toto Statement over the built artifacts, then sign with k2gl/dsse:
$statement = $provenance->toStatement([
    new ResourceDescriptor(name: 'app.phar', digest: ['sha256' => '…']),
]);
$envelope = $statement->sign($signer);   // K2gl\Dsse\Envelope

Parsing back (after verifying the envelope's signatures):

use K2gl\InToto\Statement;
use K2gl\Slsa\Provenance;

$statement  = Statement::fromEnvelope($envelope);
$provenance = Provenance::fromStatement($statement);   // checks predicateType

$provenance->buildDefinition->buildType;          // 'https://example.com/buildtypes/v1'
$provenance->runDetails->builder->id;             // 'https://github.com/actions/runner'
$provenance->runDetails->metadata?->invocationId; // 'run-42'

SLSA Provenance v0.2

Most provenance found in real Sigstore bundles is the older v0.2 predicate (https://slsa.dev/provenance/v0.2), which has a different shape from v1. It lives under K2gl\Slsa\V02 with its own typed value objects:

use K2gl\InToto\Statement;
use K2gl\Slsa\V02\Provenance;

$statement  = Statement::fromEnvelope($envelope);   // verify signatures first
$provenance = Provenance::fromStatement($statement);

$provenance->builder->id;                              // 'https://github.com/…'
$provenance->buildType;                                // 'https://…/generic@v1'
$provenance->invocation?->configSource?->uri;          // 'git+https://github.com/…'
$provenance->metadata?->completeness?->parameters;     // true
$provenance->materials[0]->digest;                     // ['sha1' => '…']

Building one wraps it in an in-toto Statement v0.1 by default — the version real-world v0.2 provenance is paired with. The two versions are orthogonal, so the Statement version can be overridden:

use K2gl\InToto\StatementVersion;
use K2gl\Slsa\V02\Builder;
use K2gl\Slsa\V02\Provenance;

$provenance = new Provenance(
    builder: new Builder(id: 'https://github.com/actions/runner'),
    buildType: 'https://github.com/slsa-framework/slsa-github-generator/generic@v1',
);

$statement = $provenance->toStatement([$subject]);                       // in-toto Statement v0.1
$statement = $provenance->toStatement([$subject], StatementVersion::V1); // …or v1

Verification Summary (VSA)

Where provenance says how an artifact was built, a Verification Summary Attestation (https://slsa.dev/verification_summary/v1) records that a verifier checked it against a policy — which SLSA levels it reached and whether it passed. This is the attestation a verifier emits, carried by an in-toto Statement v1:

use K2gl\InToto\ResourceDescriptor;
use K2gl\Slsa\VerificationResult;
use K2gl\Slsa\VerificationSummary;
use K2gl\Slsa\Verifier;

$vsa = new VerificationSummary(
    verifier: new Verifier(id: 'https://github.com/slsa-framework/slsa-verifier', version: ['slsa-verifier' => 'v2.4.1']),
    timeVerified: '2026-07-11T12:00:00Z',
    resourceUri: 'pkg:composer/k2gl/dsse@1.3.0',
    policy: new ResourceDescriptor(uri: 'https://example.com/policy.yaml', digest: ['sha256' => '…']),
    verificationResult: VerificationResult::Passed,
    verifiedLevels: ['SLSA_BUILD_LEVEL_3'],
    slsaVersion: '1.0',
    dependencyLevels: ['SLSA_BUILD_LEVEL_3' => 5],   // optional
);

$statement = $vsa->toStatement([
    new ResourceDescriptor(name: 'dsse.zip', digest: ['sha256' => '…']),
]);
$envelope = $statement->sign($signer);

Parsing back (after verifying the envelope's signatures):

use K2gl\InToto\Statement;
use K2gl\Slsa\VerificationResult;
use K2gl\Slsa\VerificationSummary;

$statement = Statement::fromEnvelope($envelope);
$vsa       = VerificationSummary::fromStatement($statement);   // checks predicateType

$vsa->verificationResult === VerificationResult::Passed;  // true
$vsa->verifiedLevels;                                     // ['SLSA_BUILD_LEVEL_3']
$vsa->policy->digestFor('sha256');                        // '…'

Predicate registry

use K2gl\InToto\Statement;
use K2gl\Slsa\Predicates;
use K2gl\Slsa\Provenance;

Predicates::register();                  // registers v1, v0.2 and VSA in the shared registry

$statement = Statement::fromEnvelope($envelope);
$predicate = $statement->predicate();    // a K2gl\Slsa\Provenance (or V02\Provenance), else the raw array

if ($predicate instanceof Provenance) {
    echo $predicate->buildDefinition->buildType;
}

License

MIT — see LICENSE. Independent, clean-room implementation of the SLSA Provenance specification.

k2gl / slsa-provenance

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