From e937da62ebf3d842d26fc285e434de567fe9b67c Mon Sep 17 00:00:00 2001
From: Sertug17 <104278804+Sertug17@users.noreply.github.com>
Date: Fri, 7 Aug 2026 23:48:38 +0300
Subject: [PATCH] fix(gate): use timingSafeEqual to prevent timing attacks on
 password check

The previous comparison used !== which short-circuits on the first
mismatched character. An attacker measuring response latency across
many requests can converge on the correct password one character at
a time.

Replace with node:crypto timingSafeEqual, which always takes constant
time regardless of where the buffers differ. Length is checked first
(not timing-sensitive) since timingSafeEqual requires equal-length
buffers.
---
 app/api/gate/route.ts | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/app/api/gate/route.ts b/app/api/gate/route.ts
index 6cd1b78..7ab38f5 100644
--- a/app/api/gate/route.ts
+++ b/app/api/gate/route.ts
@@ -1,3 +1,5 @@
+import { timingSafeEqual } from 'node:crypto';
+
 import { NextResponse } from 'next/server';
 
 // Verifies the temporary site password (see middleware.ts) and, on success,
@@ -27,7 +29,22 @@ export async function POST(request: Request) {
     provided = '';
   }
 
-  if (provided !== password) {
+  // Use timingSafeEqual to prevent timing attacks: a naive string comparison
+  // (`provided !== password`) returns early on the first mismatched character,
+  // leaking information about how many leading characters are correct. An
+  // attacker can measure response latency across many requests and converge on
+  // the password one character at a time. timingSafeEqual always takes the same
+  // amount of time regardless of where the buffers differ.
+  //
+  // Buffers must be the same length for timingSafeEqual, so a length mismatch
+  // is checked first (and is itself not timing-sensitive).
+  const providedBuf = Buffer.from(provided);
+  const passwordBuf = Buffer.from(password);
+  const match =
+    providedBuf.length === passwordBuf.length &&
+    timingSafeEqual(providedBuf, passwordBuf);
+
+  if (!match) {
     return NextResponse.json({ ok: false }, { status: 401 });
   }