Could our behaviour be turned into a password?
30 May 2014 Last updated at 17:10 BST
From fingerprint and iris scanners to voice verification, biometric technology is becoming an increasingly widespread security tool.
But for some people, this technology can feel intrusive and they may be unwilling to cooperate.
BBC Click's David Reid reports on how security systems are now looking at how our unique behaviour - the way we walk, talk and use computers and tablets - to confirm our identity.