An algorithm for automatically choosing distractors for recognition based authentication using minimal image types

<p>When a user logs on to a recognition based authentication system, he or she is presented with a number of images, one of which is their pass image and the others are distractors. The user must recognise and select their own image to enter the system. If any of the distractors is too similar to the target, the user is likely to become confused and may well choose a distractor by mistake.</p> <p>It is simple for humans to rule on image similarity but such a labour intensive approach hinders the wider uptake of these mechanisms. Automating image similarity detection is a challenging problem but somewhat easier when the images being used are minimal image types such as hand drawn doodles and Mikons constructed using a computer tool.</p> <p>We have developed an algorithm, which has been reported earlier, to automatically detect if two doodle images are similar. This paper reports a new experiment to discover the amount of similarity in collections of doodles and Mikons, from a human perspective. This information is used to improve the algorithm and confirm that it also works well with Mikons.</p&gt

Measuring the revised guessability of graphical passwords

There is no widely accepted way of measuringthe level of security of a recognition-based graphical password against guessing attacks. We aim to address this by examining the influence of predictability of user choice on the guessability and proposing a new measure of guessability. Davis et al. showed that these biases exist for schemes using faces and stories, we support this result and show these biases exist in other recognition-based schemes. In addition, we construct an attack exploiting predictability, which we term “Semantic Ordered Guessing Attack” (SOGA). We then apply this attack to two schemes (the Doodles scheme and a standard recognition-based scheme using photographic images) and report the results. The results show that predictability when users select graphical passwords influence the level of security to a varying degree (dependent on the distractor selection algorithm). The standard passimages scheme show an increase on guessability of up to 18 times more likely than the usual reported guessability, with a similar set up of nine images per screen and four screens, the doodles scheme shows a successful guessing attack is 3.3 times more likely than a random guess. Finally, we present a method of calculating a more accurate guessability value, which we call the revised guessability of a recognition-based scheme. Our conclusion is that to maximise the security of a recognition-based graphical password scheme, we recommend disallowing user choice of images

Comparing the usability of doodle and Mikon images to be used as authenticators in graphical authentication systems

Recognition-based graphical authentication systems rely on the recognition of authenticator images by legitimate users for authentication. This paper presents the results of a study that compared doodle images and Mikon images as authenticators in recognition based graphical authentication systems taking various usability dimensions into account. The results of the usability evaluation, with 20 participants, demonstrated that users preferred Mikon to doodle images as authenticators in recognition based graphical authentication mechanisms. Furthermore, participants found it difficult to recognize doodle images during authentication as well as associate them with something meaningful. Our findings also show the need to consider the security offered by the images, especially their predictability

Empirical approach towards investigating usability, guessability and social factors affecting graphical based passwords security

This thesis investigates the usability and security of recognition-based graphical authentication schemes in which users provide simple images. These images can either be drawn on paper and scanned into the computer, or alternatively, they can be created with a computer paint program. In our first study, looked at how culture and gender might affect the types of images drawn. A large number of simple drawings were provided by Libyan, Scottish and Nigerian participants and then divided into categories. Our research found that many doodles (perhaps as many as 20%) contained clues about the participants’ own culture or gender. This figure could be reduced by providing simple guidelines on the types of drawings which should be avoided. Our second study continued this theme and asked the participants to try to guess the culture of the person who provided the image. This provided examples of easily guessable and harder to guess images. Our third study we built a system to automatically register simple images provided by users. This involved creating a website where the users could register their images and which they could later login to. Image analysis software was also written which corrected any mistakes the user might make when scanning in their images or using the Paint program. This research showed that it was possible to build an automatic registration system, and that users preferred using a paint tool rather than drawing on paper and then scanning in the drawing. This study also exposed poor security in some user habits, since many users kept their drawings or image files. This research represents one of the first studies of interference effects where users have to choose two different graphical passwords. Around half of the users provided very similar set of drawings. The last study conducted an experiment to find the best way of avoiding ‘shoulder surfing’ attacks to security when selecting simple images during the login stage. Pairs of participants played the parts of the observer and the user logging in. The most secure approaches were selecting using a single keystroke and selecting rows and columns with two key strokes

Exploring the memorability of multiple recognition-based graphical passwords and their resistance to guessability attacks

Most users find it difficult to remember traditional text-based passwords. In order to cope with multiple passwords, users tend to adopt unsafe mechanisms like writing down the passwords or sharing them with others. Recognition-based graphical authentication systems (RBGSs) have been proposed as one potential solution to minimize the above problems. But, most prior works in the field of RBGSs make the unrealistic assumption of studying a single password. It is also an untested assumption that RBGS passwords are resistant to being written down or verbally communicated. The main aim of the research reported in this thesis is to examine the memorability of multiple image passwords and their guessability using written descriptions (provided by the respective account holders). In this context, the thesis presents four user studies. The first user study (US1) examined the usability of multiple RBGS passwords with four different image types: Mikon, doodle, art and everyday objects (e.g. images of food, buildings, sports etc.). The results obtained in US1 demonstrated that subjects found it difficult to remember four RBGS passwords (of the same image type) and the memorability of the passwords deteriorated over time. The results of another usability study (US2) conducted using the same four image types (as in US1) demonstrated that the memorability of the multiple RBGS passwords created by employing a mnemonic strategy do not improve even when compared to the existing multiple password studies and US1. In the context of the guessability, a user study (GS1) examined the guessability of RBGS passwords (created in US1), using the textual descriptions given by the respective account holders. Another study (GS2) examined the guessability of RBGS passwords (created in US2), using descriptions given by the respective account holders. The results obtained from both the studies showed that RBGS passwords can be guessed using the password descriptions in the experimental set-up used. Additionally, this thesis presents a novel Passhint authentication system (PHAS).The results of a usability study (US3) demonstrated that the memorability of multiple PHAS passwords is better than in existing Graphical authentication systems (GASs). Although the registration time is high, authentication time for the successful attempts is either equivalent to or less than the time reported for previous GASs. The guessability study (GS3) showed that the art passwords are the least guessable, followed by Mikon, doodle and objects in that order. This thesis offers these initial studies as a proof of principle to conduct large scale field studies in the future with PHAS. Based on the review of the existing literature, this thesis identifies the need for a general set of principles to design usability experiments that would allow systematic evaluation and comparison of different authentication systems. From the empirical studies (US1, US2 and US3) reported in this thesis, we found that multiple RBGS passwords are difficult to remember, and the memorability of such passwords can be increased using the novel PHAS. We also recommend using the art images as the passwords in PHAS, because they are found to be the least guessable using the written descriptions in the empirical studies (GS1, GS2 and GS3) reported in this thesis

An ecologically valid evaluation of an observation-resilient graphical authentication mechanism

Alphanumeric authentication, by means of a secret, is not only a powerful mechanism, in theory, but prevails over all its competitors in reality. Passwords, as they are more commonly known, have the potential to act as a fairly strong gateway. In practice, though, password usage is problematic. They are (1) easily shared, (2) trivial to observe and (3) maddeningly elusive when forgotten. Moreover, modern consumer devices only exacerbate the problems of passwords as users enter them in shared spaces, in plain view, on television screens, on smartphones and on tablets. Asterisks may obfuscate alphanumeric characters on entry but popular systems, e.g. Apple iPhone and Nintendo Wii, require the use of an on-screen keyboard for character input. A number of alternatives to passwords have been proposed but none, as yet, have been adopted widely. There seems to be a reluctance to switch from tried and tested passwords to novel alternatives, even if the most glaring flaws of passwords can be mitigated. One argument is that there has not been sufficient investigation into the feasibility of the password alternatives and thus no convincing evidence that they can indeed act as a viable alternative. Graphical authentication mechanisms, solutions that rely on images rather than characters, are a case in point. Pictures are more memorable than the words that name them, meaning that graphical authentication mitigates one of the major problems with passwords. This dissertation sets out to investigate the feasibility of one particular observation-resilient graphical authentication mechanism called Tetrad. The authentication mechanism attempted to address two of the core problems with passwords: improved memorability and resistance to observability (with on-screen entry). Tetrad was tested in a controlled lab study, that delivered promising results and was well received by the evaluators. It was then deployed in a realistic context and its viability tested in three separate field tests. The unfortunate conclusion was that Tetrad, while novel and viable in a lab setting, failed to deliver a usable and acceptable experience to the end users. This thorough testing of an alternative authentication mechanism is unusual in this research field and the outcome is disappointing. Nevertheless, it acts to inform inventors of other authentication mechanisms of the problems that can manifest when a seemingly viable authentication mechanism is tested in the wild

Security and usability in a hybrid property based graphical authentication system

Alphanumeric text and PINs continue to be the dominant authentication methods in spite of the numerous concerns by security researchers of their inability to properly address usability and security flaws and to effectively combine usability and security. These flaws have, however, contributed to the growing research interest in the development and use of graphical authentication systems as alternatives to text based systems. Graphical passwords or graphical authentication systems are password systems that use images rather than characters or numbersin user authentication. The picture superiority effect, a belief that humans are better able to memorise images than text, has very much influenced the proliferation of and support for graphical authentication systems. In spite of their growing acceptance, however, empirical studies have shown that graphical authentication systems have also inherited some of the flaws of text based passwords. Theseflaws include predictability, vulnerability to observational attacks and the inability of systems to efficiently combine security with usability. Hence there is a continued quest among usable security researchers to find that hypothetical system that has both strong usability and strong security. In this research, a novel concept for hybrid graphical authentication systems is developed. This consists of a class of systems that are called ‘property based authentication systems’ which adopt the use of image properties for user authentication, rather than specific images as used in existing systems. Image properties are specified contents of images which gives the image a set of characteristics. Several implementations of these systems have been developed and evaluated. Significant empirical performance studies have been conducted to evaluate these systems in terms of usability and security. The usability evaluations conducted evaluate thesystems in terms effectiveness, efficiency and user satisfaction, while security evaluations measure their susceptibility to common attacks. The results from these studies suggests that property based systems have better usability and security when compared to commonly known and well researched graphical authentication systems

A STUDY OF GRAPHICAL ALTERNATIVES FOR USER AUTHENTICATION

Merged with duplicate record 10026.1/1124 on 27.02.2017 by CS (TIS)Merged with duplicate record 10026.1/1124 Submitted by Collection Services ([email protected]) on 2012-08-07T10:49:43Z No. of bitstreams: 1 JALI MZ_2011.pdf: 7019966 bytes, checksum: e2aca7edf5e11df083ec430aedac512f (MD5) Approved for entry into archive by Collection Services([email protected]) on 2012-08-07T10:50:20Z (GMT) No. of bitstreams: 1 JALI MZ_2011.pdf: 7019966 bytes, checksum: e2aca7edf5e11df083ec430aedac512f (MD5) Made available in DSpace on 2012-08-07T10:50:20Z (GMT). No. of bitstreams: 1 JALI MZ_2011.pdf: 7019966 bytes, checksum: e2aca7edf5e11df083ec430aedac512f (MD5) Previous issue date: 2011Authenticating users by means of passwords is still the dominant form of authentication despite its recognised weaknesses. To solve this, authenticating users with images or pictures (i.e. graphical passwords) is proposed as one possible alternative as it is claimed that pictures are easy to remember, easy to use and has considerable security. Reviewing literature from the last twenty years found that few graphical password schemes have successfully been applied as the primary user authentication mechanism, with many studies reporting that their proposed scheme was better than their predecessors and they normally compared their scheme with the traditional password-based. In addition, opportunities for further research in areas such as image selection, image storage and retrieval, memorability (i.e. the user’s ability to remember passwords), predictability, applicability to multiple platforms, as well as users’ familiarity are still widely possible. Motivated by the above findings and hoping to reduce the aforementioned issues, this thesis reports upon a series of graphical password studies by comparing existing methods, developing a novel alternative scheme, and introducing guidance for users before they start selecting their password. Specifically, two studies comparing graphical password methods were conducted with the specific aims to evaluate users’ familiarity and perception towards graphical methods and to examine the performance of graphical methods in the web environment. To investigate the feasibility of combining two graphical methods, a novel graphical method known as EGAS (Enhanced Graphical Authentication System) was developed and tested in terms of its ease of use, ideal secret combination, ideal login strategies, effect of using smaller tolerances (i.e. areas where the click is still accepted) as well as users’ familiarity. In addition, graphical password guidelines (GPG) were introduced and deployed within the EGAS prototype, in order to evaluate their potential to assist users in creating appropriate password choices. From these studies, the thesis provides an alternative classification for graphical password methods by looking at the users’ tasks when authenticating into the system; namely click-based, choice-based, draw-based and hybrid. Findings from comparative studies revealed that although a number of participants stated that they were aware of the existence of graphical passwords, they actually had little understanding of the methods involved. Moreover, the methods of selecting a series of images (i.e. choice-based) and clicking on the image (i.e. click-based) are actually possible to be used for web-based authentication due to both of them reporting complementary results. With respect to EGAS, the studies have shown that combining two graphical methods is possible and does not introduce negative effects upon the resulting usability. User familiarity with the EGAS software prototype was also improved as they used the software for periods of time, with improvement shown in login time, accuracy and login failures. With the above findings, the research proposes that users’ familiarity is one of the key elements in deploying any graphical method, and appropriate HCI guidelines should be considered and employed during development of the scheme. Additionally, employing the guidelines within the graphical method and not treating them as a separate entity in user authentication is also recommended. Other than that, elements such as reducing predictability, testing with multiple usage scenarios and platforms, as well as flexibility with respect to tolerance should be the focus for future research