How to get the Digital Signatures in Sharepoint 2010

See more:

SharePoint

Hi to all,

*This is siddiqali working on Sharepoint 2010.I use Designer Data Forms and & Visual webpart.

*I have come across to a point where,I need to Get the digital signatures for Users.Where when Users Download the documents,I need to collect the user name or his Users digital signatures.Can any one tell me how is it possible using workflows are visual webpart


Thanks,
Quality Communication Provides Quality Work.
Mohammad Siddiqali.