Verify customer identity with a signed JWT

Prompt awareness

The assistant also sees the caller's number in per-turn context so it stops asking for it or guessing it. That context improves the conversation, but it is not how your backend receives the number.

Customer:
- WhatsApp number: +2348012345678 (verified by the channel)
- Name: Ada Okonkwo
Their number is already attached to every tool call automatically. Never ask
for it, and never put it in a tool argument unless a field explicitly asks
for a different person's number.

The token

When the caller phone number is known, every outbound custom HTTP action request includes one signed JWT header.

X-Drusy-Identity: eyJhbGciOiJFUzI1NiIsImtpZCI6ImsxIiwidHlwIjoiSldUIn0...

Getting your keys

Each business gets its own ECDSA P-256 keypair. Drusy holds the private key. Your server uses the public key through JWKS.

GET https://api.drusy.ai/public/signing-keys/:businessId/jwks.json

{
  "keys": [
    {
      "kty": "EC",
      "crv": "P-256",
      "x": "...",
      "y": "...",
      "kid": "k1",
      "alg": "ES256",
      "use": "sig"
    }
  ]
}

Verify the JWT

Reject the request unless signature verification passes. A decoded but unverified token is just attacker-controlled text.

import { createRemoteJWKSet, jwtVerify } from "jose";

const JWKS = createRemoteJWKSet(
  new URL("https://api.drusy.ai/public/signing-keys/<businessId>/jwks.json"),
);

async function verifyDrusyIdentity(req) {
  const { payload } = await jwtVerify(req.get("x-drusy-identity"), JWKS, {
    issuer: "https://drusy.ai",
    audience: "https://api.example.com",
    algorithms: ["ES256"],
  });

  return payload.sub;
}

app.post("/drusy/lookup-customer", async (req, res) => {
  let phone;
  try {
    phone = await verifyDrusyIdentity(req);
  } catch {
    return res.sendStatus(401);
  }

  // Look the customer up by phone.
});

Body hash

The optional bh claim is base64url SHA-256 of the raw request bytes. Compute it over bytes as received, not over re-serialized JSON.

import crypto from "node:crypto";

const bh = crypto
  .createHash("sha256")
  .update(req.rawBody)
  .digest("base64url");

if (payload.bh && payload.bh !== bh) {
  return res.sendStatus(401);
}

Am I actually verifying?

The action test sheet sends a normal request, then can send a second request with a structurally valid JWT whose signature has been corrupted.

Rotation

Rotate from the dashboard or API. Drusy retires the current key and mints a new one immediately. Retired keys stay in JWKS so in-flight tokens keep verifying.

Go-live and limits