Graphical Authentication Passcode Memorability: Context, Length, and Number

Authentication verifies users’ identities to protect against costly attacks. Graphical authentication schemes utilize pictures as passcodes rather than strings of characters, numbers, and symbols. Pictures are more memorable than alphanumeric passwords. Two studies investigated the memorability of graphical passcodes when users need to remember multiple passcodes or longer passcodes. Longer passcodes provide advantages to security by protecting against brute force attacks, and multiple passcodes need to be investigated as users need to authenticate for numerous accounts. It was found that participants have strong item retention for passcodes of up to eight images and for up to eight accounts. Also, these studies examined whether context can facilitate memorability. The impact of context was not found as assumed in the literature. Overall, memorability was still higher for all the number and length passcode conditions compared with alphanumeric passwords. These studies take steps toward understanding the readiness of graphical schemes as an authentication option.