Assignment 2 – Review of the Literature
Case Study – Keystroke Biometric
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Describe problem investigated (intro + abstract)
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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)
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How the study will advance understanding
Explain why the study should be conducted
Evaluate, organize, and synthesize literature
Keystroke Biometric Studies
A Keystroke Biometric System
for Long-Text Input
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Journal article
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Authors
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Int. Journal of Information Security and Privacy
Charles C. Tappert, Sung-Hyuk Cha, Mary Villani, and
Robert S. Zack
Summarizes keystroke biometric work 2005-2010
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3 DPS dissertations
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2 on identification, 1 on missing/incomplete data
About 12 masters-level projects
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New material – authentication, longitudinal, touch-type model
Keystroke Biometric Studies
Build a Case for Usefulness of Study
(9 paragraphs of introduction)
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Validate importance of study – applications
Define keystroke biometric
Appeal of keystroke over other biometrics
Previous work on the keystroke biometric
No direct study comparisons on same data
Feature measurements
Make case for using: data over the internet,
long text input, free (arbitrary) text input
Extends previous work by authors
Summary of paper organization
Keystroke Biometric Studies
Validate importance of study –
describe important applications
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Internet authentication application
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Internet identification application
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Authenticate (verify) student test-takers
Identify perpetrators of inappropriate email
Internet security for other applications
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Important as more businesses move toward
e-commerce
Keystroke Biometric Studies
Define Keystroke Biometric
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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
Keystroke Biometric Studies
Appeal of Keystroke
over other Biometrics
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Not intrusive – data captured as users type
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Inexpensive – keyboards are common
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Users type frequently for business/pleasure
No special equipment necessary
Can continue to check ID with keystrokes
after initial authentication
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As users continue to type
Keystroke Biometric Studies
Previous Work on
the Keystroke Biometric
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Identification versus authentication
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Most studies were on authentication
Few on identification (more difficult problem)
Short versus long text input
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Most studies used short input – passwords, names
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Two commercial products on hardening passwords
Few used long text input – copy or free text
Other keystroke problems studied
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One study detected fatigue, stress, etc.
Another detected ID change via monitoring
Keystroke Biometric Studies
No Direct Study Comparisons
on Same Data
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No comparisons on a standard data set
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(desirable, available for many biometric and
pattern recognition problems)
Rather, researchers collect their own data
Nevertheless, literature optimistic of
keystroke biometric potential for security
Keystroke Biometric Studies
Feature Measurements
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Features derived from raw data
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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
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Use of good (statistical) feature measurements
Generalization over keyboards, conditions, etc.
Keystroke Biometric Studies
Make Case for Using
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Data over the internet
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Long text input
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Required by applications
More and better features
Higher accuracy
Free text input
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Required by applications
Predefined copy texts unacceptable
Keystroke Biometric Studies
Extends Previous Work by Authors
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Previous work
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Identification feasibility: fixed text & same keyboard for train/test
Improved identification system – two independent variables
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Authentication system and associated studies
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Ideal: same input mode & keyboard type for train/test
Non-ideal: different input mode and/or keyboard type for train/test
Ideal and non-ideal conditions as above
Longitudinal (over time) identification & authentication studies
Hierarchical feature/fallback model and parameter studies
New work
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Further clarifies presentation + improved results
Obtained Receiver Operating Characteristic (ROC) curves
from k-nearest-neighbor classification procedure
Keystroke Biometric Studies
Summary of Paper Organization
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Introduction (described above)
System components
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Experimental design and data collection
Experimental results
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Data capture over internet
Feature extraction
Classification – identification and authentication
ROC curve derivation – two methods
Identification
Authentication – including ROC curves
Longitudinal studies
System model and parameters
Conclusion and future work
Keystroke Biometric Studies
Build a Case for Usefulness of Study
(9 paragraphs of introduction)
1.
2.
3.
4.
5.
6.
7.
8.
9.
Validate importance of study – applications
Define keystroke biometric
Appeal of keystroke over other biometrics
Previous work on the keystroke biometric
No direct study comparisons on same data
Feature measurements
Make case for using: data over the internet,
long text input, free (arbitrary) text input
Extends previous work by authors
Summary of paper organization
Keystroke Biometric Studies
No Explicit Research
Question or Hypotheses
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Implicit research question
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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
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Performance decreases
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In going from ideal to non-ideal conditions
As time between enrollment and testing increases
As the input text length decreases
Keystroke Biometric Studies
Summary
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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
Keystroke Biometric Studies