Cryptography for ASP.NET application

Hi,


i am in process of re writing the my application from ASP.NET 1.1 TO ASP.NET 3.5/4.0.
i want to use cryptography extensively. can any one sugger good way of achiving it in a most better,roboust manner


even i am looking to buy any good thirdparty api/components in effortable price.


Thank You

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