JACS for Node.js

Cryptographic identity, signing, and verification for AI agents from Node.js.

npm install @hai.ai/jacs

Prebuilt native bindings are included. A normal install does not require compiling Rust.

Full documentation | Quick Start

Quick start

const jacs = require('@hai.ai/jacs/simple');

await jacs.quickstart({ name: 'my-agent', domain: 'agent.example.com' });
const signed = await jacs.signMessage({ action: 'approve', amount: 100 });
const result = await jacs.verify(signed.raw);
console.log(`Valid: ${result.valid}, Signer: ${result.signerId}`);

All operations are async by default. Sync variants are available with a Sync suffix, for example signMessageSync.

Core operations

| Function | Description | |----------|-------------| | quickstart(options) | Create or load a persistent agent | | load(configPath) | Load an agent from config | | signMessage(data) | Sign JSON data | | signFile(path, embed) | Sign a file | | verify(doc) | Verify a signed document | | verifyStandalone(doc, opts) | Verify without loading an agent | | audit() | Run a security audit |

Text and image provenance

Node exposes the same inline text and image signing surface as the CLI:

import * as jacs from '@hai.ai/jacs/simple';

await jacs.load('./jacs.config.json');

// Markdown/text: append and verify an inline signature block.
await jacs.signText('README.md');
const text = await jacs.verifyText('README.md');
console.log(text.status);  // 'signed' | 'missing_signature' | 'malformed'

try {
  await jacs.verifyText('README.md', { strict: true });
} catch (err) {
  if (/MissingSignature/.test(err.message)) {
    console.log('not signed');
  } else {
    throw err;
  }
}

await jacs.verifyText('README.md', { keyDir: './trusted-keys/' });

// Images: embed and verify a signature in PNG, JPEG, or WebP metadata.
await jacs.signImage('photo.png', 'signed.png');
const image = await jacs.verifyImage('signed.png');
console.log(image.status);  // 'valid'

const payload = await jacs.extractMediaSignature('signed.png');

The same methods are available on the instance-based JacsClient for multi-agent processes. These signatures prove that an agent signed specific canonical bytes at its claimed time; they do not prove first creation or legal ownership.

Verify without an agent

import { verifyStandalone } from '@hai.ai/jacs/simple';

const result = verifyStandalone(signedJson, { keyDirectory: './keys/' });

Cross-language interop is tested on every commit. Documents signed in Rust or Python verify in Node.js, and Node-signed documents verify in the other bindings.

Framework adapters

Adapters for Vercel AI SDK, Express, Koa, LangChain.js, and MCP are available. Framework dependencies are optional peer dependencies.

Instance-based API

For multiple agents in one process:

import { JacsClient } from '@hai.ai/jacs/client';

const client = await JacsClient.quickstart({ name: 'my-agent', domain: 'example.com' });
const signed = await client.signMessage({ action: 'approve' });

See DEVELOPMENT.md for the full API reference, advanced usage, framework adapter examples, and testing utilities.

Links

• JACS Documentation
• Verification Guide
• Source
• Examples