From 54449ee1359cc8534739c8f7819c43d74b4dcba7 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 15 Jul 2026 21:53:22 +0000
Subject: [PATCH] =?UTF-8?q?=F0=9F=9B=A1=EF=B8=8F=20Sentinel:=20[CRITICAL/H?=
 =?UTF-8?q?IGH]=20Fix=20timing=20attack=20vulnerability=20in=20auth=20toke?=
 =?UTF-8?q?n=20validation?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .jules/sentinel.md                         | 4 ++++
 src/cli/commands/serve.ts                  | 7 +++----
 tests/integration/prompt_templates.test.ts | 4 +++-
 3 files changed, 10 insertions(+), 5 deletions(-)
 create mode 100644 .jules/sentinel.md

diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 00000000..e5839898
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2025-02-23 - Timing attack vulnerability in Auth Token validation
+**Vulnerability:** The token length was compared before performing the comparison with `timingSafeEqual`, which leaks the secret token length via an early return timing difference.
+**Learning:** `timingSafeEqual` throws an error if buffer lengths are different, which leads to developers creating a short-circuit fast path that leaks the secret's length.
+**Prevention:** Instead of checking buffer lengths, always hash both the user input and the stored secret using SHA-256 (or another secure hash algorithm) before using `timingSafeEqual`. This ensures that both values are a fixed length, avoiding timing differences.
\ No newline at end of file
diff --git a/src/cli/commands/serve.ts b/src/cli/commands/serve.ts
index 2c37293e..891cf2e7 100644
--- a/src/cli/commands/serve.ts
+++ b/src/cli/commands/serve.ts
@@ -349,10 +349,9 @@ export async function handleServeCommand(_options: unknown, command: Command) {
             const tokenBuffer = Buffer.from(token);
             for (const authToken of authTokens) {
               const authTokenBuffer = Buffer.from(authToken);
-              if (
-                tokenBuffer.length === authTokenBuffer.length &&
-                crypto.timingSafeEqual(tokenBuffer, authTokenBuffer)
-              ) {
+              const hash1 = crypto.createHash('sha256').update(tokenBuffer).digest();
+              const hash2 = crypto.createHash('sha256').update(authTokenBuffer).digest();
+              if (crypto.timingSafeEqual(hash1, hash2)) {
                 isAuthenticated = true;
                 break;
               }
diff --git a/tests/integration/prompt_templates.test.ts b/tests/integration/prompt_templates.test.ts
index 21905259..f1360d78 100644
--- a/tests/integration/prompt_templates.test.ts
+++ b/tests/integration/prompt_templates.test.ts
@@ -36,7 +36,9 @@ describe('Prompt templates', () => {
 
     expect(planSystem).toContain('You are SalmonLoop.');
     expect(patchSystem).toContain('You are PATCH, a phase-native diff compiler.');
-    expect(autopilotSystem).toContain('You are a senior software engineer running in "autopilot" mode.');
+    expect(autopilotSystem).toContain(
+      'You are a senior software engineer running in "autopilot" mode.',
+    );
     expect(answerSystem).toContain('You are a coding assistant in "answer" mode.');
     expect(researchSystem).toContain('You are a research assistant.');
   });