GB2476822A

GB2476822A - Observation-resistant authentication method using finger pressure determination

Info

Publication number: GB2476822A
Application number: GB1000356A
Authority: GB
Inventors: Paul Michael Dunphy; David Kim; James Nicholson; John Nicholson; Jonathan Hook; Pamela Briggs; Patrick Olivier
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-01-11
Filing date: 2010-01-11
Publication date: 2011-07-13
Anticipated expiration: 2030-01-11
Also published as: GB2476822B; GB201000356D0

Abstract

Observation-resistant authentication methods are likely to become increasingly important, as situated computing technologies such as tabletop interfaces and public displays become habitual. The method includes the user placing the fingers of both hands on a multi-touch surface substantially perpendicularly to each other. A grid is defined by the fingers, the grid containing a number of cells each containing an object. The method further includes the user communicating the coordinate of an object (x,y) by increasing pressure on fingers (x,y) on the edge of the grid. The multi-touch surface records this increased pressure and maps the coordinates to the object in the grid. This is repeated until the user has identified all objects in their authentication sequence and access can then be allowed or denied. The location of the objects in the grid can be varied after each input. Not all five fingers on each hand may be used. The authentication method is particularly resistant to shoulder-surfing.

Description

Invention Record Form i. Title: Authentication by Multi-Level Pressure Exertion on Multi-touch Interfaces

3. Description

3.1. Background

Knowledge-based authentication systems have an innate vulnerability to being compromised at the point of login using simple observation techniques (or shoulder surfing). An attacker can then used information gained to launch a replay attack where the observed credentials are re-used at a later time. As pervasive technologies become more widely accepted and deployed, there is a pressing need to explore authentication procedures that are resistant to the observation they are likely to incur.

One PIN entry mechanism designed to be resistant to shoulder surfing is the cognitive trapdoor game by Roth et al (2004) where the PIN is not explicitly exposed. bin knowledge of the PIN is crucial to completion. One drawback is that PIN entry times are increased by tell times over a control group not using the enhancement. Tan et al (2005) proposed a Spy-Resistant Keyboard, although much like Cognitive Trapdoor Game system, it took a long time to authenticate.

Graphical Passwords (Suo et. al 2005) are increasingly proposed as usable knowledge-based authentication mechanisms.

These are based on a strong conceptual basis that humans have more effective memory for images than words an numbers. Tan et al., 2006 discovered that non-dictionary alphanumeric passwords were more observable than graphical Passfaccs graphical passwords. Wiedenbeck et al (2006) propose the Convex Hull Click scheme where users identify a number of their objects in a larger set of objects (in this case icons) and are required to click within the convex hull formed by the positioning of the objects on screen. This system has the benefit that users do not directly click on their objects, therefore making it difficult to observe. A similar system using text instead of icons was proposed by Zhao and Li (2007) with the exception that the user is required to type a character that is inside the area instead of clicking.

Malek et. al describe a pen pressure-based solution that is based on the draw a secret (Jermyn et. al. 1999). Here the user makes a drawing on a tablet computer and pen pressure at various points of the drawing is encoded as an extra degree of complexity. The difference with our invention is that ours is multi-purpose, we exploit multi-touch technology which is a key design feature, and don't require additional hardware of the user.

Finally, gaze-based password entry has been explored by Kumar et al (2007) using eye-tracking. Although results were positive, eye tracking is still not feasible in real installations due to the high cost of hardware.

3.2. Detailed Description

We believe the invention could be deployed on public displays, tabletop interfaces or any other context that makes use of multi-touch interaction. The invention is also multi-purpose which means it is not restricted to work with one particular knowledge-based authentication scheme. This makes it applicable to graphical passwords (Suo et. al. 2005), PINs, alphanumeric passwords, or even a mixture.

A priori the user must enrol in an authentication scheme that harnesses the pressure-grid. In this process the user is assigned authentication credentials and is given time to remember them or record them in a secure manner. The invention is used in the authentication phase, where the user must demonstrate knowledge of their assigned credentials.

Firstly for calibration the user is required to initially place fingers on the interface. Then, relative to the finger positions an NxN grid is displayed. The grid is already populated with objects. of which the user is challenged to select any components of their original password sequence that appear in the grid. Objects in the grid are referenced by an (x,y) coordinate system, and one hand of the user is assigned x, and the other v. Each finger on the hands are assigned x=l, x=2...x=5. or y=1. y=2..y=5. In order to select an object the user is required to exert additional pressure on one finger per hand to communicate an (x,y) coordinate that identifies their chosen object. (see Figure 1). The user will only be authenticated if they correctly select all their objects. If a user fails one or more grids, they will not be authenticated and they will have the opportunity to try again.

Figure 1: The grid of objects (grey), green dots indicate fingers resting upon the surface. To select the object in the grid highlighted yellow; pressure is increased on one finger per hand (orange), the intersection of this in the grid communicates the object.

The system is effective as users do not directly touch the desired object, thus not revealing it to any observers. The attacker is required to simultaneously determine which finger on each hand is exerting pressure. and the object to which the pressure maps. Also the solution allows fast entry of authentication credentials, in our own evaluation we have seen PIN entry and Passfaces graphical password entry affected by only a few seconds.

3.3. References Roth, V., Richter, K., and Freidinger, R. 2004. A PIN-entry method resilient against shoulder surfing. In Proceedings of the 11th ACM Conference on Computer and Communications Security (Washington DC, USA, October 25 -29, 2004).

CCS 04. ACM, New York, NY, 236-245.

Zhao, H., and Li, X. 2007. S3PAS: A Scalable Shoulder-Surfing Resistant Textual-Graphical Password Authentication Scheme. Advanced Information Networking and Applications Workshops, AINAW 07. 21st International Conference on, vol.2, no., 467-472, 21-23.

Wiedenbeck, 5., Waters, J., Sobrado, L., and Birget, J. 2006. Design and evaluation of a shoulder-surfing resistant graphical password scheme. In Proceedings of the Working Conference on Advanced Visual interfaces (Venezia, Italy, May 23 -26, 2006). AVI 06. ACM, New York, NY, 177-184.

Kumar, M., Garfinkel, T., Boneh, D., and Winograd. T. 2007. Reducing shoulder-surfing by using gaze-based password entry. In Proceedings of the 3rd Symposium on Usable Privacy and Security (Pittsburgh. Pennsylvania, July 18 -20, 2007). SOUPS 07, vol. 229. ACM, New York, NY, 13-19.

Taxi, F., Ozok, A. A., and Holden, S. H. 2006. A comparison of perceived and real shoulder-surfing risks between alphanumeric and graphical passwords. In Proceedings of the Second Symposium on Usable Privacy and Security (Pittsburgh, Pennsylvania, July 12 -14, 2006). SOUPS 06, vol. 149. ACM, New York, NY, 56-66.

Tan, D. S., Keyani, P.. and Czerwinski, M. 2005. Spy-resistant keyboard: more secure password entry on public touch screen displays. In Proceedings of the 17th Australia Conference on Computer-Human interaction: Citizens online: Considerations For Today and the Future (Canberra, Australia, November 21 -25, 2005). OZCFII, vol. 122. Computer-Human Interaction Special Interest Group (CHISIG) of Australia, Narrabundah, Australia, 1-10.

X. Suo, Y. Zhu, G. S. Owen, "Graphical Passwords: A Survey," 21st Annual Computer Security Applications Conference (ACSAC'OS), 2005, pp. 463-472.

B. Malek, M. Orozco, and A. El Saddik. Novel shoulder-surfing resistant haptic-based graphical password. In Proc. EuroHaptics'06, 2006.

Jermyn. I.. Mayer, A., Monrose, F., Reiter, M. K.. and Rubin, A. D. 1999. The design and analysis of graphical passwords. In Proceedings of the 8th Conference on USENIX Security Symposium -Volume 8 (Washington, D.C..

August 23 -26, 1999). USENIX Security Symposium. USENIX Association, Berkeley, CA, 1-1

Claims

4. Claims 1. An authentication entry method on multi-touch interfaces that involves the user placing fingers of both hands on a multi-touch interface; an NxN grid of objects is displayed relative to the hands, the dimensions determined by the size of the hands; within the grid, each cell contains objects and are each assigned an (x,y) coordinate; fingers of the user are also assigned x or y coordinates; with the user making selections by exerting additional pressure upon the fingers that communicate the desired (x,y) coordinate; the system then translates the finger pressure into selection of object (x.y). The objects in the grid can then either be changed everytime the user makes a selection, or kept static. This is repeated until the user has entered their entire authentication sequence and the system gives feedback as to whether the user has entered the correct sequence. If incorrect the user is able to try again.
2. As in claim 1 Where coordinates are assigned to fingers through the use of pressure zones that are used make easier the translation between finger pressure and an object. Pressure within the zone is used to associate pressure with a finger.
3. As in claim 1 Where pressure thresholds are calculated for each finger individually depending on perceived dexterity or strength, in order to determine "additional pressure".
4. As in claim 1 where the user is expected to select multiple objects in the same grid.
5. As in claim 1 where no on-screen feedback is given as to each object selected.
6. As in claim 1 where the positions of objects in the grid are randomized at each new authentication attempt.
7. As in claim 1 where less than 5 fingers per hand are used in the interaction.
8. As in claim I where objects can be symbols, images, numbers, alphabetic characters, colors, or any object representation that can be formatted into the grid. r r 0*) rAmendments to the Claims have been filed as followsCLAIMS1. A dynamically calibrated and positioned inpifi method for user authentication on a multi-touch interface comprising: the user placing the fingers of both hands upon the interface approximately one hand-width apart; whereby a grid consisting of cells that each contain an object is dynamically sized to reflect dimensions of the hand and the spacing of fingers is positioned relative to the hands, and extended to form selection zones around the fingers of each hand; enabling the user to discreetly select an object within the grid by increasing pressure upon one finger per hand that can be interpreted as selection of one row and one column.2. An authentication entry method on a multi-touch device as defined in claim 1 where hands are further spaced apart, or closer together.3. An authentication entry method on a multi-touch device as defined in claim 1 where fewer than 5 fingers per hand are used in the interaction.4. An authentication entry method on a multi-touch device as defined in claim 1 where one dimension of a Cartesian 2D coordinate is assigned to each hand, and particular values within that dimension to each finger.5. An authentication entry method on a multi-touch device as defined in claim 1 where pressure capabilities are recorded for individual fingers to inform calculation of a threshold for detection of selections by each finger.6. An authentication entry method on a multi-touch device as defined in claim 1 where no on-screen feedback is given as to which object was selected.7. An authentication entry method on a multi-touch device as defined in claim 1 where objects within the grid can be symbols, images, numbers, alphabetic characters, colors, or any representation that can be formatted into the grid.8. An authentication entry method on a multi-touch device as defined in claim 1 where the user is able to select a sequence of objects.
9. An authentication entry method on a multi-touch device as defined in claim 1 where the selection zones are not explicitly displayed. r r 0*) r