diff --git a/docs/source/advanced/security/certs.rst b/docs/source/advanced/security/certs.rst
index f23fe1a83..ee6e98b01 100644
--- a/docs/source/advanced/security/certs.rst
+++ b/docs/source/advanced/security/certs.rst
@@ -10,47 +10,47 @@ The xCAT daemon on the management node and service node listens on a SSL socket
 
 xCAT creates 1 CA certificate and 2 credentials (private key and certificate pairs):
 
-   1. xCAT CA certificate(ca.pem): 
+   1. xCAT CA certificate(ca.pem):
 
       * a self-signed certificate used as Certificate Authority in xcatd SSL communication;
-      * generated by ``/opt/xcat/share/xcat/scripts/setup-xcat-ca.sh`` script on xCAT installation; 
+      * generated by ``/opt/xcat/share/xcat/scripts/setup-xcat-ca.sh`` script on xCAT installation;
       * will be generated (or updated) on xCAT management node when:
-         * install or update xCAT when "/etc/xcat/ca" directory does not exist 
-         * or run ``xcatconfig -f|--force`` 
+         * install or update xCAT when "/etc/xcat/ca" directory does not exist
+         * or run ``xcatconfig -f|--force``
          * or run ``xcatconfig -c|--credentials``
-      * files on management node: 
+      * files on management node:
          * ``/etc/xcat/ca/ca-cert.pem``
          * ``/etc/xcat/cert/ca.pem`` ,copied by ``/opt/xcat/share/xcat/scripts/setup-server-cert.sh``
          * ``/root/.xcat/ca.pem`` ,copied by ``/opt/xcat/share/xcat/scripts/setup-local-client.sh``
       * file on service node: ``/root/.xcat/ca.pem``
-      * distribution path: 
+      * distribution path:
         **/etc/xcat/cert/ca.pem (MN)** ===(run ``xcatconfig`` command)===> **/install/postscripts/_xcat/ca.pem (MN)** ===(node provision/updatenode)==> **/xcatpost/_xcat/ca.pem (SN and CN)** ==(run "servicenode" postscript)==> **/root/.xcat/ca.pem (SN)**
 
-   2. xCAT server credential(server-cred.pem): 
+   2. xCAT server credential(server-cred.pem):
 
       * a concatenation of server private key and certificate(signed with xCAT CA certificate)
       * generated by ``/opt/xcat/share/xcat/scripts/setup-server-cert.sh`` on xCAT installation;
       * will be generated (or updated) on xCAT management node when:
-         * install or update xCAT when ``/etc/xcat/cert`` directory does not exist 
-         * or run ``xcatconfig -f|--force`` 
+         * install or update xCAT when ``/etc/xcat/cert`` directory does not exist
+         * or run ``xcatconfig -f|--force``
          * or run ``xcatconfig -c|--credentials``
       * file on management node: ``/etc/xcat/cert/server-cred.pem``
-      * file on service node: ``/etc/xcat/cert/server-cred.pem`` 
-      * distribution path: 
+      * file on service node: ``/etc/xcat/cert/server-cred.pem``
+      * distribution path:
         **/etc/xcat/cert/server-cred.pem (MN)** ==(run ``xcatserver`` script called by ``servicenode`` postscript)===> **/etc/xcat/cert/server-cred.pem(SN)**
 
    3. xCAT client credential(client-cred.pem):
 
       * a concatenation of client private key and certificate (signed with xCAT CA certificate)
       * generated by ``/opt/xcat/share/xcat/scripts/setup-local-client.sh`` on xCAT installation
-      * will be generated (or updated) on xCAT management node when: 
-         * install or update xCAT when ``/root/.xcat/client-key.pem``  does not exist; 
-         * or run ``xcatconfig -f|--force`` 
+      * will be generated (or updated) on xCAT management node when:
+         * install or update xCAT when ``/root/.xcat/client-key.pem``  does not exist;
+         * or run ``xcatconfig -f|--force``
          * or run ``xcatconfig -c|--credentials``
       * file on management node: ``/root/.xcat/client-cred.pem``
-      * file on service node: ``/root/.xcat/client-cred.pem`` 
-      * distribution path: 
-        **/root/.xcat/client-cred.pem (MN)** ===(run ``xcatclient`` script called by ``servicenode`` postscript")===> **/root/.xcat/client-cred.pem(SN)** 
+      * file on service node: ``/root/.xcat/client-cred.pem``
+      * distribution path:
+        **/root/.xcat/client-cred.pem (MN)** ===(run ``xcatclient`` script called by ``servicenode`` postscript")===> **/root/.xcat/client-cred.pem(SN)**
 
 The usage of the credentials in the xCAT SSL communication is: