Multi-touch technology interfaces are becoming omnipresent due to its user-friendly human-machine interaction. Medium to large size multi-touch interfaces are implemented using camera based systems, capacity, resistive or pressure sensing systems or LED system. This paper presents security and performance vulnerabilities of multi-touch systems implemented in a multi-user environment. The paper reviews the main related technologies and mechanisms such as authentication, auditing, non-repudiation and collision detection. The paper also proposes enhanced designs based on NFC tags and mobile readers.