XAT

Agent infrastructure for AI. Identity, trust, signing, audit. Zero dependencies.

Based on the x-agent-trust extension registered in the OpenAPI Extensions Registry.

Install

npm install xat-agent

Agent side (sign outbound requests)

const xat = require('xat-agent');

const agent = xat.createAgent({
  provider: xat.providers.file('./agent.key'),  // dev only
  keyid: 'my-agent'
});

// fetch wrapper -- Agent-Signature header added automatically
const res = await agent.fetch('https://api.example.com/v1/pay', {
  method: 'POST',
  body: JSON.stringify({ amount: 500, currency: 'usd' })
});

API side (verify inbound requests)

const xat = require('xat-agent');

app.use('/api', xat.verify({
  resolveKey: async (keyid) => {
    // look up the agent's public key by keyid
    return agents[keyid].publicKeyPem;
  }
}));

app.post('/api/pay', (req, res) => {
  console.log('Verified agent:', req.agent.keyid);
  res.json({ ok: true });
});

JWKS endpoint

app.use(xat.jwks(() => [agentPublicKeyPem]));
// serves /.well-known/agent-trust-keys automatically

Key providers

Private keys never enter XAT memory in production. The signing operation happens inside the provider boundary.

// Dev only -- file on disk
xat.providers.file('./key.pem')

// Dev only -- environment variable
xat.providers.env('XAT_PRIVATE_KEY')

// Production -- AWS KMS (key never leaves HSM)
xat.providers.awsKms({ keyId: 'arn:aws:kms:...' })

// Production -- Google Cloud KMS
xat.providers.gcpKms({ keyName: 'projects/.../cryptoKeyVersions/1' })

// Production -- HashiCorp Vault Transit
xat.providers.vault({ addr: 'https://vault:8200', keyName: 'agent-key' })

// Bring your own
xat.providers.custom({
  sign: async (data) => { /* return base64 signature */ },
  getPublicKey: async () => { /* return PEM */ }
})

Generate keys

const { publicKey, privateKey } = xat.generateKeyPair();

Lint your OpenAPI spec

npm install spectral-x-agent-trust
npx @stoplight/spectral-cli lint openapi.yaml --ruleset node_modules/spectral-x-agent-trust/ruleset.js

Links

• OpenAPI Extensions Registry
• Integration guide
• Spectral ruleset
• OWASP MCP Security Cheat Sheet

Author

Raza Sharif, CyberSecAI Ltd

License

Apache-2.0