A lightweight electronic signature scheme using Twitter?

In many application contexts, qualified electronic signature are difficult to adopt due to cost and technological reasons. As the Euro- pean legislation admits the use of (non-qualified) electronic signatures in several cases, the design of new signature protocols with cheapness and usability features is a challenging issue. In this paper, we propose a new lightweight electronic signature protocol that does not require any public key infrastructure, cryptography and dedicated device, yet guaranteeing a good level of security. The protocol is conceived for closed domains of users, such as the case of documents exchanged between employees of a company. Signature and verification processes rely on the Twitter social network and do not require any changes of its features. A system proto- type has been also designed and implemented to show that the adoption of our solution is both realistic and effective.