This article explains what is a Digital Signature, why it is an important part of the
Digital Identity, and how it works. Then it describes the authenticity and social
problems related to the usage of the Digital Signature. It explains as well the two
authentication models, X.509 and OpenPGP, that can be used to solve these
authenticity problems. Finally it makes a comparison between these two authentication
models and their features and tries to explain why the OpenPGP model is better.