Simplified Webauthn

simplewebauthn.ts

interface SimpleCredential {
  id: string;
  publicKey: ArrayBuffer;
}

async function create(name: string) : Promise<SimpleCredential> {
  // NOTE: We don't care about the challenge because we don't check attestation
  const challenge = crypto.getRandomValues(new Uint8Array(16));
  let credential = await navigator.credentials.create({
    publicKey: {
      rp: { name: "Passkey", },
      user: {
        id: crypto.getRandomValues(new Uint8Array(16)),
        name,
        displayName: name,
      },
      challenge,
      pubKeyCredParams: [{ type: "public-key", alg: -7 }],
    },
  });
  if (!(credential instanceof PublicKeyCredential)) {
    throw new Error("Unexpected credential type");
  }
  const response = credential.response
  if (!(response instanceof AuthenticatorAttestationResponse)) {
    throw new Error("Unexpected response type");
  }
  const publicKey = response.getPublicKey()
  if (!publicKey) {
    throw new Error("No public key");
  }
  return {
    id: credential.id,
    publicKey,
  }
}

async function get(id: string, challenge: ArrayBuffer) : Promise<AuthenticatorAssertionResponse> {
  let credential = await navigator.credentials.get({
    publicKey: {
      challenge,
      allowCredentials: [{ type: "public-key", id }],
    },
  });
  if (!(credential instanceof PublicKeyCredential)) {
    throw new Error("Unexpected credential type");
  }
  const response = credential.response
  if (!(response instanceof AuthenticatorAssertionResponse)) {
    throw new Error("Unexpected response type");
  }
  return response
}