Technological University Dublin ARROW@TU Dublin Dissertations School of Computer Sciences 2012 Biometric Alternatives to CAPTCHA: Exploring Accessible Interface Options Anita Foley Technological University Dublin Follow this and additional works at: https://arrow.tudublin.ie/scschcomdis Part of the Computer Engineering Commons Recommended Citation Foley, A. Biometric alternatives to CAPTCHA: exploring accessible interface options.Masters Dissertation. Technological University Dublin, 2012. This Dissertation is brought to you for free and open access by the School of Computer Sciences at ARROW@TU Dublin. It has been accepted for inclusion in Dissertations by an authorized administrator of ARROW@TU Dublin. For more information, please contact [email protected], [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License Biometric Alternatives to CAPTCHA: Exploring Accessible Interface Options Anita Foley A dissertation submitted in partial fulfilment of the requirements of Dublin Institute of Technology for the degree of M.Sc. in Computing (Assistive Technology) July 2012 I certify that this dissertation which I now submit for examination for the award of MSc in Computing (Assistive Technology), is entirely my own work and has not been taken from the work of others save and to the extent that such work has been cited and acknowledged within the test of my work. This dissertation was prepared according to the regulations for postgraduate study of the Dublin Institute of Technology and has not been submitted in whole or part for an award in any other Institute or University. The work reported on in this dissertation conforms to the principles and requirements of the Institute’s guidelines for ethics in research. Signed: _________________________________ Date: 16th July 2012 i ABSTRACT In the computing domain the relationship between accessibility and security is a complex and evolving one; accessibility attempts to ensure that as wide a range of individuals as possible are granted access to systems, whereas security attempts to restrict access only to individuals who are entitled to access those systems. A key security concern is to determine whether or not the system is being accessed by a software agent or a real human being, and a number of approaches have been developed to determine the answer to this question. This issue has been discussed throughout the history of computer science and its roots can be traced back to Alan Turing's 1950 paper "Computing Machinery and Intelligence" from which the so- called "Turing Test" derives its name. A very common approach to this question is the CAPTCHA (the "Completely Automated Public Turing test to tell Computers and Humans Apart"), which requires a human being to perform a visual test, typically recognizing alphanumeric characters that are obscured or warped in some way to make Optical Character Recognition (OCR) difficult. This seemingly effective approach highlights the essential tension between security and accessibility, since it provides significant challenges to rely on a visual character recognition test when considering users with visual impairments or learning difficulties. In this work, an accessible biometric alternative to the CAPTCHA user interface is proposed. In the event of a single sign-on biometric recognition system, the interface developed has the potential to exploit the capabilities of the iPad platform to provide universal access. The proposed interface, BioScope, is implemented using accessible development and evaluation methodologies to ensure universal and inclusive design. Following implementation, the interface is evaluated and compared with CAPTCHA using a series of surveys, questionnaires and prototype experiments with the aim of determining if BioScope’s approach is a viable accessible alternative to the CAPTCHA user interface. Keywords: Accessibility, CAPTCHA, Biometrics, Assistive Technology, Universal Design. ii ACKNOWLEDGEMENTS I’d like to begin with thanking my supervisor, Ciarán O’Leary, for his guidance, support and enthusiasm throughout this process. This dissertation has meant more to me than any other item of work I have completed thus far in my life and for that I am eternally grateful. I’d also like to thank my family and friends for their support and patience over the past 2 years. Their encouragement never went unnoticed and without it none of this would have been possible. Finally, I’d like to thank my boyfriend and partner in crime, David, for encouraging and motivating me each and every day. Your positive attitude and outlook on life is a constant inspiration to me that I would truly be lost without. iii TABLE OF CONTENTS 1 INTRODUCTION ............................................................................................. 1 1.1 BACKGROUND TO RESEARCH ........................................................................... 1 1.2 RESEARCH AIM ............................................................................................... 2 1.3 RESEARCH OBJECTIVES ................................................................................... 3 1.4 RESEARCH METHODOLOGY ............................................................................. 4 1.5 PROJECT DELIVERABLES ................................................................................. 5 1.6 RESOURCES .................................................................................................... 5 1.7 SCOPE AND LIMITATIONS ................................................................................ 6 1.8 ORGANISATION OF DISSERTATION ................................................................... 7 2 ACCESSIBILITY .............................................................................................. 9 2.1 INTRODUCTION ............................................................................................... 9 2.2 DEFINING ACCESSIBILITY AND USABILITY ....................................................... 9 2.3 DEFINING DISABILITY ................................................................................... 10 2.4 IMPAIRMENTS ............................................................................................... 11 2.4.1 Blind and Low Vision ......................................................................... 12 2.4.2 Learning Disabilities ......................................................................... 13 2.4.3 Physical Disabilities .......................................................................... 15 2.5 ASSISTIVE TECHNOLOGIES ............................................................................ 16 2.5.1 Braille................................................................................................ 16 2.5.2 Screen Reader .................................................................................... 18 2.5.3 Switch Access..................................................................................... 18 2.5.4 Speech Synthesis ................................................................................ 19 2.6 ACCESSIBLE DESIGN ..................................................................................... 20 2.6.1 Universal Design ............................................................................... 20 2.6.2 Apple User Experience Guidelines ..................................................... 23 2.6.3 Web Content Accessibility Guidelines ................................................ 23 2.7 ACCESSIBILITY TOOLS .................................................................................. 25 2.7.1 International Classification of Functioning ........................................ 25 2.7.2 Exclusion Calculator ......................................................................... 25 2.8 ACCESSIBILITY AND USABILITY TESTING ....................................................... 27 iv 2.8.1 Nielsen’s Usability Measurements ..................................................... 28 2.8.2 SUMI Questionnaire .......................................................................... 28 2.9 ACCESSIBILITY MOTIVATIONS ....................................................................... 29 2.9.1 United States of America .................................................................... 29 2.9.2 Ireland ............................................................................................... 30 2.9.3 United Kingdom ................................................................................. 30 2.10 CONCLUSION ............................................................................................. 31 3 CAPTCHA ....................................................................................................... 32 3.1 INTRODUCTION ............................................................................................. 32 3.2 CAPTCHA DEFINITION ................................................................................ 32 3.3 TURING TEST ................................................................................................ 33 3.4 TEXT-BASED CAPTCHA .............................................................................. 33 3.4.1 GIMPY .............................................................................................. 34 3.4.2 Google CAPTCHA ............................................................................. 36 3.4.3 reCAPTCHA ...................................................................................... 37 3.5