The book Building Secure ASP.NET Applications (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/SecNetHT10.asp) contains a section titled How To: Create An Encryption Library that may be of help to you.

-Mike

>I've been playing around with this a bit, but can't figure out how to do something that would seem pretty simple.
>
>It's pretty simple to encrypt or decrypt a file (see MSKB#307010). However, I'd just like to do this with a string. I can't figure out how to do this without writing the string to a file, then use the techniques demonstrated in the KB article.
>
>Any suggestions?