slsa-provenance

slsa-provenance is a skill for Claude Code from sbom-tool/gh-guard. It costs 26 tokens per session (1,391 once invoked), scanned A, original, MIT.

A release workflow for Rust packages that publishes a crate and creates SLSA Level 3 provenance. Provenance is a signed record showing what source code was built and which builder produced it.

In plain words
What is it for?
Use it to test, package, hash, and publish Rust crates; create signed .intoto.jsonl provenance files; and attach that record to a GitHub release.
Why use it?
It helps users verify that a published package came from the expected source and build process. It also separates publishing, provenance creation, and release steps.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the gh-guard plugin — 14 skills, 5 commands shipped together

Good fit Use it to test, package, hash, and publish Rust crates; create signed .intoto.jsonl provenance files; and attach that record to a GitHub release.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sbom-tool/gh-guard/slsa-provenance
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add sbom-tool/gh-guard --skill slsa-provenance
Clone the repo
git clone --depth 1 https://github.com/sbom-tool/gh-guard

Made for: Claude Code.

Or install gh-guard, the plugin that ships this one along with the rest of its 14 skills, 5 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for slsa-provenance

README.md
[![agentmods](https://agentmods.dev/badge/skills/sbom-tool/gh-guard/slsa-provenance/github.svg)](https://agentmods.dev/skills/sbom-tool/gh-guard/slsa-provenance)
Your own site
<a href="https://agentmods.dev/skills/sbom-tool/gh-guard/slsa-provenance"><img src="https://agentmods.dev/badge/skills/sbom-tool/gh-guard/slsa-provenance/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for slsa-provenance

Your own site · 80×15
<a href="https://agentmods.dev/skills/sbom-tool/gh-guard/slsa-provenance"><img src="https://agentmods.dev/badge/skills/sbom-tool/gh-guard/slsa-provenance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,391 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00026 $0.01391
Opus 5 $0.00013 $0.00696
Sonnet 5 $0.00005 $0.00278
Haiku 4.5 $0.00003 $0.00139

Measured 10d ago against content hash aa85e40304fa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

slsa-provenance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/slsa-provenance/SKILL.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SLSA L3 Provenance for Rust Crates

SLSA (Supply-chain Levels for Software Artifacts) Level 3 provides verifiable build provenance — a signed attestation of what was built, from what source, by which builder. This skill covers the three-job pipeline architecture for Rust crates.

Architecture

The publish workflow uses three sequential jobs:

publish ──→ provenance ──→ release
  │              │              │
  ├─ Tests       ├─ SLSA L3     ├─ Download provenance
  ├─ Verify tag  │  generator   ├─ Create GitHub Release
  ├─ Package     │  (reusable)  └─ Attach .intoto.jsonl
  ├─ Hash .crate │
  ├─ Auth OIDC   │
  └─ Publish     │
                 │
          Generates signed
          .intoto.jsonl
          attestation

Job 1: publish

  • Checks out code with fetch-depth: 0 (needed for ancestry verification)
  • Verifies tag matches Cargo.toml version
  • Verifies tagged commit is ancestor of origin/main
  • Runs tests and cargo-deny
  • Packages the crate (cargo package --locked)
  • Generates SHA-256 hash of the .crate file
  • Authenticates via OIDC and publishes

Output: hashes — base64-encoded SHA-256 subject hashes

Job 2: provenance

  • Uses the SLSA GitHub generator reusable workflow
  • Takes the hash subjects from the publish job
  • Generates a signed .intoto.jsonl attestation (DSSE envelope)
  • Uploads as a workflow artifact

Critical constraints:

  • MUST use @tag reference (e.g., @v2.1.0), not SHA — the reusable workflow requires this
  • Uses upload-assets: false because we attach provenance to the release ourselves (needed for immutable releases)

Job 3: release

  • Downloads the provenance artifact from the previous job
  • Creates a GitHub Release with the .intoto.jsonl file attached
  • Uses --verify-tag to ensure the tag exists

Critical constraint for immutable releases: If your GitHub org has "immutable releases" enabled, you CANNOT upload assets after a release is created. The provenance file must be attached AT creation time, which is why this job downloads the artifact first, then creates the release with it in a single gh release create call.

Read the full file on GitHub · 145 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 145 lines · 26 tokens per session scan A aa85e40304fa

Subscribe to this mod's changes

slsa-provenance is a skill published in the GitHub repository sbom-tool/gh-guard (15 stars, last pushed 5mo ago), licensed MIT. It adds 26 tokens to every session and 1,391 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.