1. Keystroke Biometric Studies Assignment 2 – Review of the Literature Case Study – Keystroke Biometric Describe problem investigated (intro + abstract) Developed keystroke biometric system for long-text input, identification/authentication performance, two independent variables – keyboard type/input mode, longitudinal studies Build case for usefulness of the study (introduction) How the study will advance understanding Explain why the study should be conducted Evaluate, organize, and synthesize literature

2. Keystroke Biometric Studies A Keystroke Biometric System for Long-Text Input Journal article Int. Journal of Information Security and Privacy Authors Charles C. Tappert, Sung-Hyuk Cha, Mary Villani, and Robert S. Zack Summarizes keystroke biometric work 2005-2010 3 DPS dissertations 2 on identification, 1 on missing/incomplete data About 12 masters-level projects New material – authentication, longitudinal, touch-type model

3. Keystroke Biometric Studies Build a Case for Usefulness of Study (9 paragraphs of introduction) 1. Validate importance of study – applications 2. Define keystroke biometric 3. Appeal of keystroke over other biometrics 4. Previous work on the keystroke biometric 5. No direct study comparisons on same data 6. Feature measurements 7. Make case for using: data over the internet, long text input, free (arbitrary) text input 8. Extends previous work by authors 9. Summary of paper organization

4. Keystroke Biometric Studies Validate importance of study – describe important applications Internet authentication application Authenticate (verify) student test-takers Internet identification application Identify perpetrators of inappropriate email Internet security for other applications Important as more businesses move toward e-commerce

5. Keystroke Biometric Studies Define Keystroke Biometric The keystroke biometric is one of the less-studied behavioral biometrics Based on the idea that typing patterns are unique to individuals and difficult to duplicate

6. Keystroke Biometric Studies Appeal of Keystroke over other Biometrics Not intrusive – data captured as users type Users type frequently for business/pleasure Inexpensive – keyboards are common No special equipment necessary Can continue to check ID with keystrokes after initial authentication As users continue to type

7. Keystroke Biometric Studies Previous Work on the Keystroke Biometric Identification versus authentication Most studies were on authentication Few on identification (more difficult problem) Short versus long text input Most studies used short input – passwords, names Two commercial products on hardening passwords Few used long text input – copy or free text Other keystroke problems studied One study detected fatigue, stress, etc. Another detected ID change via monitoring

8. Keystroke Biometric Studies No Direct Study Comparisons on Same Data No comparisons on a standard data set (desirable, available for many biometric and pattern recognition problems) Rather, researchers collect their own data Nevertheless, literature optimistic of keystroke biometric potential for security

9. Keystroke Biometric Studies Feature Measurements Features derived from raw data Key press times and key release times Each keystroke provides small amount of data Data varies from different keyboards, different conditions, and different entered texts Using long text input allows Use of good (statistical) feature measurements Generalization over keyboards, conditions, etc.

10. Keystroke Biometric Studies Make Case for Using Data over the internet Required by applications Long text input More and better features Higher accuracy Free text input Required by applications Predefined copy texts unacceptable

11. Keystroke Biometric Studies Extends Previous Work by Authors Previous work Identification feasibility: fixed text & same keyboard for train/test Improved identification system – two independent variables Ideal: same input mode & keyboard type for train/test Non-ideal: different input mode and/or keyboard type for train/test Authentication system and associated studies Ideal and non-ideal conditions as above Longitudinal (over time) identification & authentication studies Hierarchical feature/fallback model and parameter studies New work Further clarifies presentation + improved results Obtained Receiver Operating Characteristic (ROC) curves from k-nearest-neighbor classification procedure

12. Keystroke Biometric Studies Summary of Paper Organization Introduction (described above) System components Data capture over internet Feature extraction Classification – identification and authentication ROC curve derivation – two methods Experimental design and data collection Experimental results Identification Authentication – including ROC curves Longitudinal studies System model and parameters Conclusion and future work

13. Keystroke Biometric Studies Build a Case for Usefulness of Study (9 paragraphs of introduction) 1. Validate importance of study – applications 2. Define keystroke biometric 3. Appeal of keystroke over other biometrics 4. Previous work on the keystroke biometric 5. No direct study comparisons on same data 6. Feature measurements 7. Make case for using: data over the internet, long text input, free (arbitrary) text input 8. Extends previous work by authors 9. Summary of paper organization

14. Keystroke Biometric Studies No Explicit Research Question or Hypotheses Implicit research question What identification and authentication performance (accuracy) can be attained by a long-text-input keystroke biometric system and how does performance vary over various controlled changes Implicit research hypotheses Performance decreases In going from ideal to non-ideal conditions As time between enrollment and testing increases As the input text length decreases

15. Keystroke Biometric Studies Summary Describe problem investigated (intro + abstract) Developed keystroke biometric system for long-text input, identification/authentication performance, two independent variables – keyboard type/input mode, longitudinal studies Build case for usefulness of the study (introduction) How the study will advance understanding Explain why the study should be conducted Evaluate, organize, and synthesize literature