Adding Security for Custom WCF MessageHeaders in Silverlight platform

How can we add security for custom message headers of WCF Service in Silverlight service.

For example, I wa开发者_StackOverflownt to pass a important (authenticated) string value ( credentials) through WCF Message Headers.

Is there any possibility to pass the secured string data over message headers?

Temporarily We just passing the authenticated values as encrypted text.

Find more details at http://msdn.microsoft.com/en-us/library/system.security.cryptography.aes.aspx