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Palabras clave: Incertidumbre y variabilidad, Gestión del Riesgo, Control integrado de plazos y programación 1. Resumen Ampliando el trabajo de investigación que los autores desarrollan sobre la incertidumbre en los proyectos, en este artículo analizaremos como influye la presencia de un riesgo estacional sobre la programación del Proyecto, en func...
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... There are a number of strategies that have been developed to resist the Shoulder-Surfing attack such as in (Chalkias et al. 2006;Gao et al. 2008Gao et al. , 2010Brostoff et al. 2010;Zakaria et al. 2011;Chiang and Chiasson et al. 2013). However, most of these strategies have faced the challenge of accomplishing a secure and usable strategy. ...
... The draw a secret scheme (DAS) is extended by Chalkias et al. (2006) in order to reduce the effect of the password centering by using a multi-grid construction. Therefore, as every user has own custom grid, this makes it difficult to attackers to acquire the password. ...
With the revolution of smart devices that have become the basis of our daily lives, the majority of users rely on them to save their personal and sensitive information. As a result, users are increasingly interested in authentication processes, which is a challenge for designers to provide a secure and usable authentication process. The pattern password is one of the most selected authentication methods, since the recent development in alternative authentication interfaces for smart phones, tablets and touch screens laptops. Although drawing a pattern seems easier than typing a password, it has a major security drawback which is the shoulder-surfing attack. Therefore, this paper proposes a shoulder-surfing resistance approach for mobile devices using Camouflage Patterns method which allows choosing a very short password, while insuring that the password remains hidden amongst a large number of nodes draws. Based on this approach, three techniques are introduced and implemented using an Android platform. An experimental study is conducted for evaluating the security and usability aspects. The results showed that the proposed approach is reasonably resistant against shoulder-surfing attacks and usable for users. Accordingly, this approach is recommended for designers in order to provide very simple and yet very complicated passwords, to be observed by the attacker, at the same time.
... TheFigure 1 shows Drawing-A-Secret (DAS) scheme. Other implementation alternatives of DAS scheme (Chalkias et al., 2006; Lin et al., 2007; Tao and Adams, 2008; Thorpe and Van Oorschot, 2004) are also represented inFig. 1. ...
... to choose a small drawing grid and then draw the password. Multi-grid scheme was designed by Chalkias et al. (2006) as an Passlogix V-GO system is one of password schemes based on the improvement of DAS. In this scheme, grid-squares not identical Blonder's technique developed by Passlogix and Microsoft in large in size and shape, where user draws a design on a display grid scale. ...
Password authentication has become a widely recognized element of computer security practices where human users are proven or confirmed as legitimate u sers for access to secure systems. Using this syste m, every user needs to recall its password correctly b efore access can be granted to an intended services or applications. Remembering the secure passwords is a n everyday problem for users because of individual memory limitation. In an effort to solve this probl em, graphical password was presented as one promising athentication alternative taking advantage of pictu re superiority over texts. The main objective of th is study is to provide a comprehensive survey of array of gr aphical password schemes in different categories ba sed on their common features with the primary aim of id entifying the memorability features and propose a n ew graphical authentication system with enhanced memorability features.
... The users are given an option to choose a predefined Multi-Grid template to draw their password and the final password produced by the scheme can be composed from several internal grids. According to [7], the purpose of proposing the different grid cell size is to reduce users from creating passwords which are centred. In the Multi-Grid DAS scheme, users are allowed to focus on a single internal grid or a nested grid. ...
... In the Multi-Grid DAS scheme, users are allowed to focus on a single internal grid or a nested grid. As a result, an attacker has to use even harder massive brute-force techniques to find the password used due to the various neighbouring cells utlized [7]. From the survey results carried out in [7], the Multi-Grid DAS scheme managed to reduce the shift errors issue made by the users. ...
... As a result, an attacker has to use even harder massive brute-force techniques to find the password used due to the various neighbouring cells utlized [7]. From the survey results carried out in [7], the Multi-Grid DAS scheme managed to reduce the shift errors issue made by the users. The results, however, left the ordering error unchanged. ...
... Therefore, many researchers have proposed improvements. Chalkias, for instance, put together grids of different size refocusing the attention of the user to area besides the central part whereas Dunphy proposes the presence of a background image that enables the user to draw a password of higher security [5,6]. Nevertheless, the security of DAS largely depends on user behavior and is in the end quite vulnerable to "watching" attacks as the password image can be gained through mere observation. ...
In this paper, we present a novel user-friendly graphical password scheme resistant against "watching" attacks. Snapshot, remote monitoring, and shoulder-surfing have in common that all these attacks act as if one could directly watch the users' behavior on the screen, resulting in an insecure use of alphanumeric passwords ("watching" attacks). New technology based on graphical passwords uses graphs as authentication media where the user identifies, reproduces, or interacts with graphs to prove his identity, which partly blocks the danger. However, current graphical passwords such as D-A-S, PassPoints, Passfaces TM, and the algorithms D. Hong and Sobrado, etc. proposed are either too complicated or ineffective against "watching" attacks. In our proposal, the authentication process uses familiar images that only true users can recognize. It is hard to fabricate even many previous authentication processes are totally exposed. Furthermore a detailed application in OTP, which basically establishes an extra OTP input encryption, is discussed and its security analysis is presented.
... YAGP, proposed by Gao et al. (2008), is an extension of DAS where approximately correct drawings can be accepted, based on Levenshtein distance string matching and 'trend quadrants' analysing the direction of strokes. Other similar schemes, such as Multi-grid password (Chalkias et al., 2006), Pass-Go (Tao and Adams, 2008) and Grid Selection (Thorpe and Van Oorschot, 2004), focus on extending the usability or enhancing the authentication precision of DAS. ...
Considerable studies verified that people are vulnerable to multiple passwords interference in alphanumeric passwords but few studies in graphical passwords. We conducted a study on multiple password interference in graphical passwords and examined the effects on users' behaviour and performance. DAS, PassPoints and PassFaces, three canonical graphical passwords, represent the three main memory categories: recall, cued-recall and recognition. PassPoints were divided into PassPoints-I and PassPoints-II, corresponding to associated and unassociated cued-recall memory respectively. The study results indicate that the multiple password interference exercises strong impacts in PassFaces and is significant in DAS and PassPoints-II only in the long-term memory, while has no impact in PassPoints-I. From psychological analysis, it is clear that recall-based, recognition-based and associated cued-recall-based schemes are all susceptible to multiple password interference to some extent, while unassociated cued-recall based is not subject to memory password interference.
... Moreover, DAS requires the user to cross the same cell and lift the pen in exactly the same place, creating a major challenge of memorability for users and entryerrors frequently occur. The results of experiments in [19] have demonstrated these. Recently, new DAS-based schemes have emerged. ...
... Through investigation, we found that all of the 4 participants with low success rate set the graphical password with more than 6 long strokes and they drew the secrets at the highest speed. In [19], there is a DAS success rate survey. Although the experiments of [19] and our YAGP are not entirely the same in terms of participant, process and hardware , etc., the data may be of value as a reference. ...
... In [19], there is a DAS success rate survey. Although the experiments of [19] and our YAGP are not entirely the same in terms of participant, process and hardware , etc., the data may be of value as a reference. As shown in [19], the matched rates of DAS are 47% for non-technically inclined participants and 60% for technically literate participants. ...
Passwords are used in the vast majority of computer and communication systems for authentication. The greater security and memorability of graphical passwords make them a possible alternative to traditional textual passwords. In this paper we propose a new graphical password scheme called YAGP, which is an extension of the Draw-A-Secret (DAS) scheme. The main difference between YAGP and DAS is soft matching. The concepts of the stroke-box, image-box, trend quadrant, and similarity are used to describe the images characteristics for soft matching. The reduction in strict user input rules in soft matching improves the usability and therefore creates a great advantage. The denser grid granularity enables users to design a longer password, enlarging the practical password space and enhancing security. Meanwhile, YAGP adopts a triple-register process to create multi-templates, increasing the accuracy and memorability of characteristics extraction. Experiments illustrate the effectiveness of YAGP.
... The users are given an option to choose a predefined Multi-Grid template to draw their password and the final password produced by the scheme can be composed from several internal grids. According to [7], the purpose of proposing the different grid cell size is to reduce users from creating passwords which are centred. In the Multi-Grid DAS scheme, users are allowed to focus on a single internal grid or a nested grid. ...
... In the Multi-Grid DAS scheme, users are allowed to focus on a single internal grid or a nested grid. As a result, an attacker has to use even harder massive brute-force techniques to find the password used due to the various neighbouring cells utlized [7]. From the survey results carried out in [7], the Multi-Grid DAS scheme managed to reduce the shift errors issue made by the users. ...
... As a result, an attacker has to use even harder massive brute-force techniques to find the password used due to the various neighbouring cells utlized [7]. From the survey results carried out in [7], the Multi-Grid DAS scheme managed to reduce the shift errors issue made by the users. The results, however, left the ordering error unchanged. ...
Picture-based password has been proposed as an alternative authentication method to replace text-based password. Ensuring the security of picture-based password is not a simple task as picture-based objects are a lot easier to access and remember and can thus be easily guessed. In particular, shoulder surfing attack still remains as the main security threat encountered by many picture-based password authentication schemes, especially in drawmetric authentication scheme. In this paper, a novel shoulder surfing resistance mechanism has been proposed and evaluated. The proposed mechanism utilises penup event and neighbouring connectivity manipulation into a revised Background Pass-Go scheme. From the evaluation result, it has proven that the proposed mechanism achieves better results in resisting shoulder surfing attack while, at the same time, allowing a larger password space.
... Chalkias et al. [33] as well as Alexiadis et al. [34] made an extension to the DAS scheme with the aim to reduce these facts that have very serious implications to the security of the system. They proposed multi-grid passwords by using nested grids in the initial one (Figure 12). ...
... Nali and Thrope [29] examined the drawbacks of graphical passwords which include that users draw designs that are centred or symmetrical, something that decreases their security. As a solution to this situation, Chalkias et al. [33] proposed a multi-grid password scheme and they made a comparison for centred and symmetrical drawings, between non-technical and technical users. According to their survey, using a multi-grid scheme fewer participants created centred and symmetrical passwords and as a result, more users were able to create safer passwords. ...
Clustering is useful technique in the field of textual data mining. Cluster analysis divides objectsinto meaningful groups based on similarity between objects. Copious material is available from theWorld Wide Web (WWW) in response to any user-provided query. It becomes tedious for the userto manually extract real required information from this material. This paper proposes a scheme toeffectively address this problem with the help of cluster analysis. In particular, the ROCK algorithmis studied with some modifications. ROCK generates better clusters than other clusteringalgorithms for data with categorical attributes. We present an enhanced version of ROCK calledEnhanced ROCK (EROCK) with improved similarity measure as well as storage efficiency.Evaluation of the proposed algorithm done on standard text documents shows improvedperformance.
... Chalkias et al. [33] as well as Alexiadis et al. [34] made an extension to the DAS scheme with the aim to reduce these facts that have very serious implications to the security of the system. They proposed multi-grid passwords by using nested grids in the initial one (Figure 12). ...
... Nali and Thrope [29] examined the drawbacks of graphical passwords which include that users draw designs that are centred or symmetrical, something that decreases their security. As a solution to this situation, Chalkias et al. [33] proposed a multi-grid password scheme and they made a comparison for centred and symmetrical drawings, between non-technical and technical users. According to their survey, using a multi-grid scheme fewer participants created centred and symmetrical passwords and as a result, more users were able to create safer passwords. ...
This paper presents a survey of proof by knowledge authentication techniques (textpasswords, visual passwords and graphical passwords). Both new methods aremore memorable, as people have to remember images and not characters andgraphical passwords are also more secure. A total of 100 users participated in oursurvey, who after getting informed about the new authentication methods, theyanswered the questions of our questionnaire. Based on their answers, allparticipants have many passwords for their everyday needs and they try to selectpasswords that are not only memorable, but also secure. Unfortunately, they can notdeal with proper password selection and they become victims of dictionary attacks.Understanding this situation, participants were very positive in learning more aboutthe new authentication methods. They found both techniques memorable andfriendly – visual passwords at most. However, they found graphical passwords a bitmore complex and difficult to learn how to use them, something that they canovercome with small practice.
... Based on this remark, Birget et al. (2003) referred problems with the DAS scheme because of uncertainty in the clicking regions. Alexiadis et al. (2006) and Chalkias et al. (2006) made an extension to the DAS scheme and proposed "multi-grid passwords", where nested grids are used in the initial one ( Figure 2). With multi-grid passwords the users are able to create more complicated passwords and more memorable, while they have more points of focus to do their draw. ...
... The survey showed that 86% of participants drew a centered or approximately centered password, 45% of the passwords were totally symmetric and 29% were invalid. Chalkias et al. (2006) proposed a multi-grid password scheme, comparing the results between nontechnical inclined people with those that were well-informed. They found that 66% of non-technical users and 80% of technical users confirmed correctly their text passwords. ...
Proof by knowledge authentication techniques" include traditional text passwords, visual passwords and graphical passwords. The paper compares these three techniques using an experiment. A total of 100 users participated in the experiment. After getting informed about the new authentication methods, users created their own text, visual and graphical passwords. Then they tried to confirm them correctly and finally they answered in a comprehensive questionnaire that we have created. Analysing those data, we concluded that the text passwords that were created are predictable and very vulnerable to attacks. Visual passwords attracted users very much, especially those that are over 45 years old, although the passwords that they made are really easy to be cracked. Graphical passwords did not impress very much many of the users and especially men, at the beginning of the process. However, at the end they were characterized as a very friendly method, mostly from women. Furthermore, the created graphical passwords were difficult, memorable and above all very safe.
