send and verify login challenge

src/controllers/account.js

@@ -38,7 +38,28 @@ const accountController = {
         console.error("Error during registration:", error);
         return res.status(500).json({ error: "Server error during registration" });
     }
-  }
+  },
+    loginGetChallenge: async (req, res) => {
+        let randomBuffer = crypto.randomBytes(16);
+        let randomNumber = randomBuffer.toString('hex');
+        req.session.randomNumber = randomNumber;
+        return res.status(200).json({
+            message: "Challenge generated successfully",
+            challenge: randomNumber
+        });
+    },
+    loginVerifyChallenge: async (req, res) => {
+        const { signature } = req.body;
+        const publicKeys = await database.getPublicKeys();
+        const msg = new TextEncoder().encode(req.session.randomNumber);
+        const sig = new TextEncoder().encode(signature);
+        let validKey = authentication.verifySignature(msg, sig, publicKeys);
+        if (validKey !== null) {
+            return res.status(200).json({ message: "Challenge solved successfully" });
+        } else {
+            return res.status(400).json({ error: "Challenge failed" });
+        }
+    }
 };
 
 module.exports = accountController;