diff --git a/requirements.txt b/requirements.txt
index e30c06f..44295ac 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
-cryptography>=42.0.0
+# 零依赖:纯 stdlib。签名需 AES,构建环境 pip 装 cryptography 会卡(疑 PyPI 不通),
+# 故设为可选——签名不可用时提交走 token-only。确认需签名后再解决 crypto。