1. Privacy-preserving, user-centric VoIP CAPTCHA challenges: An integrated solution in the SIP environment. (14th March 2016) Authors: Tasidou, Aimilia; Efraimidis, Pavlos S.; Soupionis, Yannis; Mitrou, Lilian; Katos, Vasilios Journal: Information and computer security Issue: Volume 24:Number 1(2016) Page Start: 2 Record Type: Journal Article View Content: Available online (eLD content is only available in our Reading Rooms) ↗