To change the cipher for all the websites published through the Blue Coat reverse proxy, you have to individually change the cipher for all of the https-reverse-proxy services you’ve created.
The following example shows how to make the changes for a webserver that is using the (domain.com) https-reverse-proxy service:
(config proxy-services)# edit domain.com
(config domain.com)# attribute cipher-suite <choose the cipher required>
(config domain.com)# exit