lammert - 2:23 pm on May 27, 2010 (gmt 0)

Adding digital signatures to documents is quite well documented. You could use digitally signed PDF documents for example. Linking that digital signature to the actual person will be the most difficult step. In the Netherlands people can obtain a legally valid personal digital signature from some specialized notary offices. Other certificates are most of the time not recognized. Especially not self-signed certificates because they are not issued by an independent authority who can check the identity of the person. But procedures may be different in other countries.