Add generateAssertionCredentials

4 files changed, 39 insertions, 2 deletions

diff --git a/package-lock.json b/package-lock.json
index 675ebc9..d009b2c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1057,6 +1057,11 @@
         }
       }
     },
+    "base64url": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/base64url/-/base64url-3.0.1.tgz",
+      "integrity": "sha512-ir1UPr3dkwexU7FdV8qBBbNDRUhMmIekYMFZfi+C/sLNnRESKPl23nB9b2pltqfOQNnGzsDdId90AEtG5tCx4A=="
+    },
     "bcrypt-pbkdf": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/bcrypt-pbkdf/-/bcrypt-pbkdf-1.0.2.tgz",
diff --git a/package.json b/package.json
index 7adcb55..370ed08 100644
--- a/package.json
+++ b/package.json
@@ -21,5 +21,8 @@
   },
   "keywords": [
     "webauthn"
-  ]
+  ],
+  "dependencies": {
+    "base64url": "^3.0.1"
+  }
 }
diff --git a/src/assertion/generateAssertionCredentials.ts b/src/assertion/generateAssertionCredentials.ts
new file mode 100644
index 0000000..fc43097
--- /dev/null
+++ b/src/assertion/generateAssertionCredentials.ts
@@ -0,0 +1,27 @@
+import base64url from 'base64url';
+
+/**
+ * Prepare credentials for user registration via navigator.credentials.get(...)
+ *
+ * @param challenge Random string the authenticator needs to sign and pass back
+ * @param credentialIDs Array of base64-encoded authenticator IDs registered by the user for
+ * assertion
+ * @param timeout How long (in ms) the user can take to complete attestation
+ */
+export default function generateAssertionCredentials(
+  challenge: string,
+  credentialIDs: string[],
+  timeout: number = 60000,
+) {
+  return {
+    publicKey: {
+      challenge: Uint8Array.from(challenge, c => c.charCodeAt(0)),
+      allowCredentials: credentialIDs.map(id => ({
+        id: base64url.toBuffer(id),
+        type: 'public-key',
+        transports: ['usb', 'ble', 'nfc'],
+      })),
+      timeout,
+    },
+  };
+}
diff --git a/src/index.ts b/src/index.ts
index bbe3ec4..d20824a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,7 @@
-import generateAttestationCredentials from "./attestation/generateAttestationCredentials";
+import generateAttestationCredentials from './attestation/generateAttestationCredentials';
+import generateAssertionCredentials from './assertion/generateAssertionCredentials';
 
 export {
   generateAttestationCredentials,
+  generateAssertionCredentials,
 };