signing and encrypting using PKI certificate (not authenticode)

[one]

Hi everyone,

I have been looking around for info to do this:

http://www.contoso.com/question.aspx?name=microsoft
=> signing and encrypting using server and client certificate (public and
private key) => http://www.contoso.com/question.aspx?G+1VMWPD==BNTW
(And the server to do a request.querystring and decrypt/check signature...)

Could someone please point me to the right direction?

I am using Visual Studio 2005 and should I be using CyptoAPI and DPAPI?
Sample code will be a "Godsend".

Really appreciate your patience,
one

 

[one]

Sorry, just to correct the payload:
http://www.contoso.com/question.aspx?payload=G+1VMWPD==BNTW