A Picture Memory.

Beginning around 1996, numerous graphical password schemes have been proposed, motivated by improving password usability and security, two key factors in password scheme evaluation. In this paper, we focus on the security aspects of existing graphical password schemes, which not only gives a simple introduction of attack methods but also intends to provide an in-depth analysis with specific schemes. The paper first categorizes existing graphical password schemes into four kinds according to the authentication style and provides a comprehensive introduction and analysis for each scheme, highlighting security aspects. Then we review the known attack methods, categorize them into two kinds, and summarize the security reported in some user studies of those schemes. Finally, some suggestions are given for future research.

A Survey on the Use of Graphical Passwords in Security

Secrets and lies.

We present a similarity metric for Android unlock patterns to quantify the effective password space of user-defined gestures. Our metric is the first of its kind to reflect that users choose patterns based on human intuition and interest in geometric properties of the resulting shapes. Applying our metric to a dataset of 506 user-defined patterns reveals very similar shapes that only differ by simple geometric transformations such as rotation. This shrinks the effective password space by 66% and allows informed guessing attacks. Consequently, we present an approach to subtly nudge users to create more diverse patterns by showing background images and animations during pattern creation. Results from a user study (n = 496) show that applying such countermeasures can significantly increase pattern diversity. We conclude with implications for pattern choices and the design of enrollment processes.

On quantifying the effective password space of grid-based unlock gestures

Graphical passwords (GPWs) are convenient for mobile equipments with touch screen. Topological graphic passwords (Topsnut-gpws) can be saved in computer by classical matrices and run quickly than the existing GPWs. We research Topsnut-gpws by the matching of view, since they have many advantages. We discuss: configuration matching partition, coloring/labelling matching partition, set matching partition, matching chain, etc. And, we introduce new graph labellings for enriching Topsnut-matchings and show that these labellings can be realized for trees or spanning trees of networks. In theoretical works we explore Graph Labelling Analysis, and show that every graph admits our extremal labellings and set-type labellings in graph theory. Many of the graph labellings mentioned are related with problems of set matching partitions to number theory, and yield new objects and new problems to graph theory.

Topological Graphic Passwords And Their Matchings Towards Cryptography.

Graphical passwords have been proposed as an alternative to alphanumeric passwords with their advantages in usability and security. However, most of these alternate schemes have their own disadvantages. For example, cued-recall graphical password schemes are vulnerable to shoulder-surfing and cannot prevent intersection analysis attack. A novel cued-recall graphical password scheme CBFG (Click Buttons according to Figures in Grids) is proposed in this paper. Inheriting the way of setting password in traditional cued-recall scheme, this scheme is also added the ideology of image identification. CBFG helps users tend to set their passwords more complex. Simultaneously, it has the capability against shoulder surfing attack and intersection analysis attack. Experiments illustrate that CBFG has better performance in usability, especially in security.

Licheng Ma

Papers

A Survey on the Use of Graphical Passwords in Security

A Novel Cued-recall Graphical Password Scheme