Question: I would like to protect a pdf document using Adobe Digital Edition. I think that it is currently being used to protect the eBooks to prevent illegal circulation. 

Can any one throw some light on that. Is it possible to do it using C# or something ?

Answer: 
You may want to have a look at [Adobe Content Server](http://www.adobe.com/products/contentserver/) and the [Adobe Digital Publishing Technology Center](http://www.adobe.com/devnet/digitalpublishing/) websites for some direction.
Yes, you can use C#: [See SDK Info Doc](http://web.archive.org/web/20100604014756/http://www.adobe.com/devnet/digitalpublishing/pdfs/ADE_LauncherSDK_DevNet.pdf). You can use any server side processing language.