From cbe9a0bffd591e7e8a0f7ec2849e3a437b0d03c1 Mon Sep 17 00:00:00 2001
From: Flow Mind <noreply@flow-mind.store>
Date: Tue, 5 May 2026 11:03:06 +0300
Subject: [PATCH] sec: constant-time admin token compare

Direct == on admin token leaks length-bytes via timing channel.
Replace with subtle.ConstantTimeCompare. Pre-prod hardening for
multi-tenant deploy where admin token grants user-creation rights.
---
 handlers.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/handlers.go b/handlers.go
index 338e7fcd..a7771986 100644
--- a/handlers.go
+++ b/handlers.go
@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"context"
+	"crypto/subtle"
 	"database/sql"
 	"encoding/base64"
 	"encoding/json"
@@ -124,7 +125,8 @@ func (s *server) GetHealth() http.HandlerFunc {
 func (s *server) authadmin(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		token := r.Header.Get("Authorization")
-		if token != *adminToken {
+		// Constant-time compare to avoid timing-attack leak of admin token bytes.
+		if subtle.ConstantTimeCompare([]byte(token), []byte(*adminToken)) != 1 {
 			s.Respond(w, r, http.StatusUnauthorized, errors.New("unauthorized"))
 			return
 		}