A comparative usability study of two-factor authentication


Event Usable Security Workshop (USEC), 2014


Emiliano De Cristofaro
Honglu Du
Julien Freudiger
Gregory Norcie
Technical Publications
February 23rd 2014
Two-factor authentication (2F) aims to enhance resilience of password-based authentication by requiring users to provide an additional authentication factor, e.g., a code generated by a security token. However, it also introduces non-negligible costs for service providers and requires users to carry out additional actions during the authentication process. In this paper, we present an exploratory comparative study of the usability of 2F technologies. First, we conduct a pre-study interview to identify popular technologies as well as contexts and motivations in which they are used. We then present the results of a quantitative study based on a survey completed by 219 Mechanical Turk users, aiming to measure the usability of three popular 2F solutions: codes generated by security tokens, one-time PINs received via email or SMS, and dedicated smartphone apps (e.g., Google Authenticator). We record contexts and motivations, and study their impact on perceived usability. We find that 2F technologies are overall perceived as usable, regardless of motivation and/or context of use. We also present an exploratory factor analysis, highlighting that three metrics ease-of-use, required cognitive efforts, and trustworthiness are enough to capture key factors affecting 2F usability.


De Cristofaro, E.; Du, H.; Freudiger, J.; Norcie, G. A comparative usability study of two-factor authentication. Usable Security Workshop (USEC), 2014.

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