Re: Wildcard certs; to use or not to use

[Sherry Callahan <scallahan () KUMC EDU>]

We use a wildcard cert on our main web server to cover www.kumc.edu<http://www.kumc.edu> and all the tertiary domains 
that the University seems to host as long as they are simple informational sites and none of the sites have anything to 
do with sensitive information.  We use UC certificates to secure our Exchange environment and a few other similar 
situations.  Otherwise, all servers have their own certs.

The hypothetical risk is that the wildcard cert could be compromised, hence compromising the encryption on any server 
using the wildcard cert.  We use Digicert so cost is not an issue - it’s free for us to request as many certs as we 
want.    Yes, we have to maintain the certs and replace them when they expire, but Digicert does a great job of 
tracking expiration dates for us as well.

Hope this helps,

Sherry Callahan
Information Security Office
University of Kansas Medical Center
(913) 588-0966 | scallahan () kumc edu<mailto:scallahan () kumc edu>



From: The EDUCAUSE Security Constituent Group Listserv [mailto:SECURITY () LISTSERV EDUCAUSE EDU] On Behalf Of Mike 
Wiseman
Sent: Tuesday, December 04, 2012 2:37 PM
To: SECURITY () LISTSERV EDUCAUSE EDU
Subject: Re: [SECURITY] Wildcard certs; to use or not to use




Has anyone used wildcard certs for their university domain? What are the pros and cons? We are in the process of moving 
our public pages to a hosting site and I've been asked if wildcard certs can be used. I assessed using wild card certs 
in the past (based on the way they wanted to use them) and deemed the risk was to great.

The environment they want to do this in now is with multiple domains on one IP address.

Any input would be appreciated.

Wildcard certs are issued  to a number of department administrators here. Our practice around using them is that they 
must be administered by one IT group only to maintain the security of the private key.  This is usually useful since 
many departments make use of a single domain level and, with a wildcard cert, they have only one cert/key to worry 
about renewing and replacing.

Mike



Mike Wiseman
Manager, Information Security
Information + Technology Services
University of Toronto