1 files changed, 33 insertions, 0 deletions
diff --git a/api/auth/_generateRegistrationOptionsForNewUser.ts b/api/auth/_generateRegistrationOptionsForNewUser.ts
new file mode 100644
index 0000000..b9417e9
--- /dev/null
+++ b/api/auth/_generateRegistrationOptionsForNewUser.ts
@@ -0,0 +1,33 @@
+import RELYING_PARTY from './_relyingParty';
+import { generateRegistrationOptions } from '@simplewebauthn/server';
+
+/**
+ * Generates options for a user without an existing account on the website to
+ * register a new authenticator and remembers the generated challenge.
+ *
+ * This function assumes that no user already exists with the given ID.
+ * It's the responsibility of the caller to make sure this assumption is true.
+ *
+ * If the user already has an account, they can't yet add more authenticators.
+ * This feature might be added in a future version of the website if there is a
+ * demonstrable need for it (or if I just get bored one day).
+ */
+export default async function generateRegistrationOptionsForNewUser(userId: string, displayName: string) {
+  const options = await generateRegistrationOptions({
+    rpName: RELYING_PARTY.name,
+    rpID: RELYING_PARTY.id,
+
+    userID: userId,
+    userName: displayName,
+
+    // Don't prompt users for additional information about the authenticator
+    attestationType: 'none',
+
+    // Prevents users from re-registering existing authenticators. In our case,
+    // we only allow new users right now, so they don't have any existing
+    // authenticators.
+    excludeCredentials: []
+  });
+
+  return options;
+}