How to digitally sign Open Office XML document in client-server paradigm with ASP .NET webservices?

I want to create a web application that can access a smart card with a digital certificate, and then digitally sign an open office XML document on the server. I know a couple of open source frameworks that do this in Java, but the client requires me to do it in .NET C#:

The SignServer Dot Org

The belgian eID Applet

Anyone has some guidelines or recommendations how to implement this .NET C#?

Has the PackageDigitalSignatureManager from Sys开发者_运维技巧tem.IO.Packaging has some use?

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You can use system.io.packaging (see the related question about this) and you can use our OfficeBlackbox components.