33 / Users can sign up and log in with WebAuthn (#39)

* Installs @vercel/postgres

* Installs @simplewebauthn/server

* Installs @simplewebauthn/browser

* Git-ignores all files starting with .env

* Reorganises folders in API

* Defines User type

* Defines Subscription type

* Defines Authenticator type

* Sets up table definition file

* Can get user from database

* Can add user to database

* Can get user's current challenge

* Can set user's current challenge

* Can get user's authenticators from database

* Can get authenticator by ID from database

* Can add user authenticator to database

* Can update authenticator in database

* Defines Relying Party information

* Can generate registration options

* Can verify registration response

* Defines registration API endpoint

* Defines user API endpoint

* Reorganises API functions on frontend

* Can access authentication API functions on frontend

* Can generate authentication options

* Can verify authentication response

* Documents the registration flow

* Fix dev_csso

* Form styling

* WIP adds sign up page

1 files changed, 47 insertions, 0 deletions

diff --git a/api/auth/_generateAuthenticationOptions.ts b/api/auth/_generateAuthenticationOptions.ts
new file mode 100644
index 0000000..562c50a
--- /dev/null
+++ b/api/auth/_generateAuthenticationOptions.ts
@@ -0,0 +1,47 @@
+import RELYING_PARTY from './_relyingParty';
+import simplewebauthn from '@simplewebauthn/server';
+import getUser from '../db/_getUser';
+import getAuthenticators from '../db/_getAuthenticators';
+import setCurrentChallenge from '../db/_setCurrentChallenge';
+
+/**
+ * Generates options for a user with an existing account on the website to
+ * authenticate using an authenticator which is already associated with their
+ * account in the database.
+ * 
+ * If a user doesn't currently have an account, they have to create one first,
+ * get their account ID and register an authenticator.
+ * 
+ * The result should be consumed by \@simplewebauthn/browser's
+ * `startAuthentication()` method.
+ */
+export default async function generateAuthenticationOptions(userId: string) {
+  const user = await getUser(userId);
+  if (!user) {
+    return Promise.reject(`
+      Failed to generate authentication options because user with ID ${userId}
+      did not exist.
+    `);
+  }
+
+  const userAuthenticators = await getAuthenticators(userId, ['id', 'transports', 'type']);
+  const textEncoder = new TextEncoder();
+
+  const options = await simplewebauthn.generateAuthenticationOptions({
+    rpID: RELYING_PARTY.id,
+
+    // Users must use one of the authenticators they've already registered
+    allowCredentials: userAuthenticators.map((authenticator) => {
+      return {
+        ...authenticator,
+        id: textEncoder.encode(authenticator.id),
+      };
+    }),
+
+    userVerification: 'preferred',
+  });
+
+  setCurrentChallenge(userId, options.challenge);
+
+  return options;
+}