diff --git a/is-my-code-constant-time?.md b/is-my-code-constant-time?.md
index f1c564c..3c1d48e 100644
--- a/is-my-code-constant-time?.md
+++ b/is-my-code-constant-time?.md
@@ -110,3 +110,6 @@ type Curve interface {
 ```
 
 其实，sm2 key exchange和[SEC 1, Version 2.0](https://www.secg.org/sec1-v2.pdf), Section 3.4 Elliptic Curve MQV Primitive 描述的方法类似，只是最后取shared secret方法不同: ECMQV和DH一样，都只取X轴值。
+
+## 相关代码
+https://github.com/emmansun/gmsm/commit/8f7a7626baba61ba9c44371a71cd8bec0dbedc6f