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?

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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