Required?: NO
The security profile lets you declare which digest algorithm you wish to use. If you are using the tcprofileregistration method then you can get a list of valid digest algorithms supported by the server from the tc profile in the tool-consumer-info section:
<security-profile> <digest-algorithms> <algorithm>MD5</algorithm> <algorithm>SHA</algorithm> </digest-algorithms> </security-profile>
The only supported algorithms are MD5 or SHA; MD5 is used by default.