wshobson--agents/plugins/signed-audit-trails

signed-audit-trails

A teaching skill for setting up cryptographically signed audit trails on every Claude Code tool call. Cookbook-style walkthrough with runnable examples.

What this is

A skill (not a runtime hook): a set of instructions and examples that explain the pattern end-to-end. Use this when you are figuring out whether receipts are the right fit for your project. Once you know they are, install the protect-mcp plugin for the actual hooks.

When to use this plugin

• Learning the pattern before committing to infrastructure
• Evaluating whether signed audit trails fit your compliance need
• Teaching team members the three-invariant cryptographic model (JCS canonicalization + Ed25519 signatures + hash chains)
• Walking a client or auditor through a live demonstration of tamper detection

For production use, the protect-mcp plugin gives you the runtime hooks directly. This plugin is the skill file you invoke via Skill when you want the concept explained in-session.

What is inside

skills/signed-audit-trails-recipe/SKILL.md

A single skill file containing:

• Step-by-step setup (Cedar policy, hook configuration, first receipt)
• Live tamper detection walkthrough
• Receipt format explanation (three invariants)
• Cross-implementation interoperability table
• CI/CD integration snippet (GitHub Actions)
• Composition with SLSA provenance for agent-built software
• Common pitfalls and references

Standards

• Ed25519 (RFC 8032) for receipt signatures
• JCS (RFC 8785) for deterministic JSON canonicalization before signing
• Cedar (AWS) for policy evaluation
• IETF draft draft-farley-acta-signed-receipts

Related plugins in this marketplace

• protect-mcp — the runtime hook implementation
• review-agent-governance — require human approval before review-surface actions; composes with protect-mcp

License

MIT. Same as the adjacent governance-category plugins in this marketplace.