diff --git a/in/public/security/openssl/index.rst b/in/public/security/openssl/index.rst
index dbf83d6..3591db5 100644
--- a/in/public/security/openssl/index.rst
+++ b/in/public/security/openssl/index.rst
@@ -232,3 +232,20 @@ Sign request
   -set_serial 0 \
   -days 730 \
   -out "certificate.crt" \
+
+----
+
+from CA key & certificate
+-------------------------
+
+.. code:: shell
+
+ openssl \
+ x509 \
+ -CA ca.crt \
+ -CAkey ca.key \
+ -req \
+ -in "client.csr" \
+ -days 365 \
+ -out "client.crt" \
+ -set_serial nn