Authenticate a passkey

Similar to passkey registration, authentication is a three-step process:

1. Authorised in your backend
2. Authenticated in your frontend
3. Verified in your backend

Backend: authorise authentication

You don’t need a username here. Passkeys are discoverable, meaning the browser/device will prompt the user to select the passkey they want to sign in with:

backend/authenticate.ts

import { Passlock } from "@passlock/server";

// from your development tenancy settings
const passlock = new Passlock({
  tenancyId: "myTenancyId",
  apiKey: "myApiKey"
});

const result = await passlock.authorizePasskeyAuthentication({
  rpId: "example.com", // "localhost" for development
  discoverable: true, // allow the user to select their passkey
});

if (result.success) {
  return result.authenticationToken;
}

Frontend: authenticate the passkey

Pass the authenticationToken to authenticatePasskey:

frontend/authenticate.ts

import { Passlock } from "@passlock/browser";

const passlock = new Passlock({ tenancyId: "myTenancyId" });

loginButton.addEventListener("click", async () => {
  const authenticationToken = await fetchTokenFromBackend();

  const result = await passlock.authenticatePasskey({
    authenticationToken
  });

  if (result.success) {
    await submitTokenToBackend(result.value.code);
  }
});

Submit the code to your backend.

Backend: verify the passkey

After your backend exchanges the code with the Passlock API, use the userId or authenticatorId (passkeyId) to lookup the user and sign them in.

backend/authenticate.ts

import { Passlock } from "@passlock/server";

// from your development tenancy settings
const passlock = new Passlock({
  tenancyId: "myTenancyId",
  apiKey: "myApiKey"
});

const result = await passlock.exchangeCode({ code });

if (result.success) {
  const user = await lookupUserById(result.value.userId);
  // alternatively identify the user by their passkey id
  const user = await lookupUserByPasskeyId(principal.authenticatorId);
};

The response is an ExtendedPrincipal.