Proteg is a software that allows users to secure their personal or notebook computers by preventing unauthorized access. It fortifies the existing Windows login mechanism by binding the user account to a ubiquitous hardware device: A portable USB storage device (USB Key, USB flash drive, thumbdrive). An additional hardware component becomes compulsory in order to login to the computer, instead of relying solely on the conventional username and password pair.

Offering greater security than passwords alone, this hardware based system (commonly known as a two-factor authentication system) creates a physical link between a user and his identity. In a two-factor authentication system like Proteg, the user is required to present the physical hardware (something the user has) and provide the correct password (something the user knows) that corresponds to the said hardware in order to gain legitimate access to the system.