Request Body의 필드마다 서명하지 않고, 데이터 전체에 대해 서명하도록 개선

src/lib/server/services/auth.ts

@@ -149,7 +149,7 @@ export const upgradeToken = async (
   const client = await getClient(challenge.clientId);
   if (!client) {
     error(500, "Invalid challenge answer");
-  } else if (!verifySignature(answer, sigAnswer, client.sigPubKey)) {
+  } else if (!verifySignature(Buffer.from(answer, "base64"), sigAnswer, client.sigPubKey)) {
     error(401, "Invalid challenge answer signature");
   }