Sharepoint: How to add audience filter to custom control?

In MOSS 2007 I want to add a custom control to the global link section of a master page and have it only visible to a particular audience.

The audienc开发者_开发百科e are the members of an active directory group who have logged in via SSL and need to be given a link which will log them out.

How can I filter a custom control so that only these users will see it? Is there an API or something like Sharepoint:SPSecurityTrimmedControl which might help?

Yes there is an API for audiences. Here are some links from MSDN to get you started:

• Audiences Overview
• Audience Object Model Overview
• Targeting Content Using Audiences (several how-tos and code samples)

I haven't come across a security trimmed control for audiences but it should be fairly easy to write one.