# Etch

> Etch is a signed audit chain for AI agent decisions, offline-verifiable against pinned public keys. Every event is signed with a hybrid Ed25519 + FIPS 205 SLH-DSA-SHA2-128f envelope, Merkle-chained into an epoch, and epoch-anchored on Sigstore Rekor + Bitcoin OpenTimestamps.

> world-model-mcp is persistent memory plus a post-quantum-signed, offline-verifiable audit trail for AI coding agents (FIPS 205 hybrid Ed25519 + SLH-DSA), MIT-licensed and fully local.

Etch is a hosted platform + reference OSS verifier. Try it in 30 seconds without signing up: `curl -X POST https://etch.systems/v1/your-project`. The response returns a bearer token and an MCP endpoint. Point any MCP-compliant client at `https://etch.systems/mcp` with the token.

Etch is an independent evidence custodian for AI agents: it produces records an AI vendor can hand to its auditor, customer or insurer, verifiable without trusting the vendor or Etch.

## Key claims (each caveat travels in the same sentence as the number)

- 14 of 14 chain-tamper attacks in the current adversarial-benchmark corpus are caught by the offline verifier (scope claim, not completeness; new attack classes may be added later).
- Two projects use Etch today: our own world-model-mcp (dogfood) + saha (design partner). Pre-revenue; no paying-customer claim is made anywhere.
- Etch maps to the evidence requirements (R5, R6) of CSA's AARM specification. Etch does not intercept or decide actions, so it does not claim full AARM Core conformance. Etch did not author AARM.
- Try the OSS live-signed demo (no signup, no network): `pip install -U world-model-mcp && world-model demo`. Signs three decisions into a hybrid-signed epoch, verifies VALID, mutates one byte to prove tamper detection fires (INVALID), restores, drops a receipt.

## Product

- [Landing](https://etch.systems/): value proposition + who holds the record + comparison to hash-only logs + admissibility-grade primitives.
- [For AI vendors](https://etch.systems/for-ai-vendors): prove what your agents did to customers and auditors.
- [For auditors](https://etch.systems/for-auditors): verify agent records without trusting the vendor.
- [For insurers](https://etch.systems/for-insurers): evidence for underwriting and claims.
- [Evidence mapping](https://etch.systems/evidence-mapping): how Etch evidence maps to AIUC-1 E015, the EU Product Liability Directive, and the IETF agent evidence draft, including what Etch does not prove.
- [Pricing](https://etch.systems/pricing): free tier, Pilot, Enterprise, partner and assessor license.
- [Signup](https://etch.systems/signup): 30-second signup for a persistent project.
- [Docs](https://etch.systems/docs): entry point + endpoint catalog.

## Try it now (no signup)

- [Quickstart](https://etch.systems/docs/quickstart): 10-minute walkthrough + try-it-now curl.
- [MCP client integration](https://etch.systems/docs/mcp-clients): per-client config (Claude Code, Cursor, Continue, Cline, Codex).
- [FAQ](https://etch.systems/docs/faq): plain-language answers to the questions asked most often about signed audit chains for AI agents.

## Compare Etch to

- [Etch vs Sigstore Rekor](https://etch.systems/vs/sigstore-rekor): positioning against Sigstore's transparency log.
- [Etch vs C2PA](https://etch.systems/vs/c2pa): positioning against the Coalition for Content Provenance and Authenticity envelope standard.
- [Etch vs hash-only + plain-log](https://etch.systems/): landing comparison table.

## Framework alignment

- [AARM conformance](https://etch.systems/aarm): mapping to SR 11-7, EU AI Act Article 12, ISO 42001, NIST AI RMF, and SOC 2 CC7.
- [Evaluations](https://etch.systems/evals): the axes an auditor should judge a signed-audit-chain product on.
- [RFP response kit](https://etch.systems/rfp-kit): pre-answered RFP for enterprise procurement.

## Open source layer

- On the pre-registered SWE-bench Verified repeat-mistake benchmark, world-model-mcp memory improved the pass rate by +10.2 points as a single-trial upper bound (67.3% to 77.6% on 49 paired instances); the multi-seed mean effect is +0.24 per instance, 95% CI [0, 0.47]. This is a world-model-mcp memory claim, not an Etch evidence claim.
- [world-model-mcp on PyPI](https://pypi.org/project/world-model-mcp/): the OSS memory server Etch is built on.
- [world-model-mcp on GitHub](https://github.com/SaravananJaichandar/world-model-mcp): source repository, MIT licensed.

## Provenance and academic references

- [Zenodo DOI 10.5281/zenodo.20834508](https://doi.org/10.5281/zenodo.20834508): the provenance-graded-knowledge technical note.
- FIPS 205 SLH-DSA-SHA2-128f: post-quantum signature scheme used in the hybrid envelope.
- FIPS 186-5 Ed25519: classical signature scheme in the hybrid envelope.
- FIPS 180-4 SHA-256: Merkle-tree hash primitive.

## What Etch is NOT

- Not a media-provenance envelope (that lane is C2PA and SPIF). Etch signs decisions, not content.
- Not a transparency log (that lane is Sigstore Rekor). Etch is a per-project chain that anchors epochs on Rekor.
- Not a watermarking system. Etch records who reviewed an output and what they applied, not whether a specific model touched the text.