Add startAttestation method to browser

1 files changed, 45 insertions, 0 deletions

diff --git a/packages/browser/src/methods/startAttestation.ts b/packages/browser/src/methods/startAttestation.ts
new file mode 100644
index 0000000..3b955cc
--- /dev/null
+++ b/packages/browser/src/methods/startAttestation.ts
@@ -0,0 +1,45 @@
+import {
+  PublicKeyCredentialCreationOptionsJSON,
+  EncodedAuthenticatorAttestationResponse,
+  AttestationCredential,
+} from '@webauthntine/typescript-types';
+
+import toUint8Array from '../helpers/toUint8Array';
+import toBase64String from '../helpers/toBase64String';
+import supportsWebauthn from '../helpers/supportsWebauthn';
+
+/**
+ *
+ */
+export default async function startAttestation(
+  creationOptionsJSON: PublicKeyCredentialCreationOptionsJSON
+): Promise<EncodedAuthenticatorAttestationResponse> {
+  if (!supportsWebauthn()) {
+    throw new Error('Webauthn is not supported in this browser');
+  }
+
+  // We need to convert some values to Uint8Arrays before passing the credentials to the navigator
+  const publicKey: PublicKeyCredentialCreationOptions = {
+    ...creationOptionsJSON.publicKey,
+    challenge: toUint8Array(creationOptionsJSON.publicKey.challenge),
+    user: {
+      ...creationOptionsJSON.publicKey.user,
+      id: toUint8Array(creationOptionsJSON.publicKey.user.id),
+    },
+  };
+
+  // Wait for the user to complete attestation
+  const credential = await navigator.credentials.create({ publicKey });
+
+  if (!credential) {
+    throw new Error('Attestation was not completed');
+  }
+
+  const { response } = (credential as AttestationCredential);
+
+  // Convert values to base64 to make it easier to send back to the server
+  return {
+    base64AttestationObject: toBase64String(response.attestationObject),
+    base64ClientDataJSON: toBase64String(response.clientDataJSON),
+  };
+}