@ariada-org/haes

Hash-anchored Evidence Stream — a tamper-evident append-only ledger for AI-artifact transparency under EU Regulation 2024/1689 (the EU AI Act) Article 50.

Open source under EUPL-1.2. Zero runtime dependencies. Node 22 LTS or newer.

What this package does

Every AI artifact a regulated product emits — a chatbot reply, an AI-generated UI string, an AI-suggested code patch, an AI-rendered image — gets written as an entry that records the model id, the prompt template fingerprint, the input redaction profile, the output checksum, the deployer's decision (shipped / rewritten / blocked), an Ed25519 signature, and a SHA-256 link to the previous entry. Mutating any entry mechanically invalidates every subsequent entry's prev_hash, so tampering detection becomes deterministic rather than discretionary.

Daily Merkle roots over the chain can be published to a third-party public log so regulators and auditors can verify integrity without trusting the deployer's tooling.

Install

npm install @ariada-org/haes

Usage

import {
  HaesClient,
  buildMerkleRoot,
  generateEd25519Keypair,
  sha256Hex,
  verifyInclusionProof,
  buildInclusionProof,
} from "@ariada-org/haes";

const key = generateEd25519Keypair();
const client = new HaesClient({ signingKey: key });

await client.append({
  payload: {
    model_id: "anthropic:claude-3-7-sonnet",
    model_version: "20250203",
    prompt_template_fingerprint: sha256Hex("system prompt v1"),
    input_redaction_profile: "pii-strict-v2",
    output_checksum: sha256Hex("output bytes"),
    decision: "shipped",
    signing_key_id: key.keyId,
  },
});

// End-to-end chain verification.
const verdict = await client.verifyAll(() => key.publicKeyRaw);
console.log(verdict.valid);

// Daily Merkle root over all entries — anchor it to a public log of choice.
const entries = await client.snapshot();
const hashes = entries.map((e) => e.entry_hash);
const root = buildMerkleRoot(hashes);

// Inclusion proof for one entry against that root.
const proof = buildInclusionProof(hashes, 0);
verifyInclusionProof(proof, root ?? "");

API

| Export | Type | Description | | ------------------------ | -------- | --------------------------------------------------- | | HaesClient | class | Append + verify orchestrator over a storage backend | | buildEntry | function | Build a signed entry from an AppendInput | | computeEntryHash | function | Canonical SHA-256 over the JCS-encoded pre-image | | verifyEntry | function | Single-entry chain-link + signature verifier | | verifyChain | function | Sequential whole-chain verifier | | buildMerkleRoot | function | SHA-256 Merkle root over leaf hashes | | buildInclusionProof | function | Per-entry inclusion proof against the daily root | | verifyInclusionProof | function | Re-verify a leaf-to-root proof | | canonicalize | function | RFC 8785 JSON canonicalization (JCS) | | generateEd25519Keypair | function | Fresh Ed25519 signing keypair (Node crypto) | | InMemoryStorage | class | Reference HaesStorageBackend implementation |

Standards referenced

• RFC 8785 — JSON Canonicalization Scheme (JCS)
• RFC 8032 — Edwards-Curve Digital Signature Algorithm (Ed25519)
• FIPS 180-4 — SHA-256
• RFC 6962 §2.1 — Merkle hash trees
• Crockford base32 — ULID layout

License

EUPL-1.2 for code; CC-BY-SA-4.0 for prose; CC0-1.0 for build config. See LICENSE and NOTICE.