Introduction to Biometrics

1
Introduction to Biometrics

• Dr. Bhavani Thuraisingham
• The University of Texas at Dallas
• Lecture 14
• Behavioral Biometrics
• October 10, 2005

2
Outline

• Definition and Example
• Signature Scan
• Keystroke Dynamics

3
References

• Course Text Book, Chapter 9
• http//www.biometricsinfo.org/signaturerecognition
  .htm
• http//et.wcu.edu/aidc/BioWebPages/Biometrics_Keys
  troke.html

4
Definition

• While Physiological biometrics is based on a
  persons physical properties, Behavioral
  biometrics is based on a persons behavior
• Examples include
• Voice Scan, Signature Scan, Keystroke Dynamics,
  Manner of walking, running, etc.
• Difficult to distinguish between physiological
  and behavioral biometrics

5
Signature Scan Introduction

• Signature verification is the process used to
  recognize an individuals hand-written signature.
  
• Dynamic signature verification technology uses
  the behavioral biometrics of a hand written
  signature to confirm the identity of a computer
  user.
• This is done by analyzing the shape, speed,
  stroke, pen pressure and timing information
  during the act of signing.
• As a replacement for a password or a PIN number,
  dynamic signature verification is a biometric
  technology that is used to positively identify a
  person from their handwritten signature.

6
Signature Scan Introduction (Continued)

• There is an important distinction between simple
  signature comparisons and dynamic signature
  verification.
• Both can be computerized, but a simple comparison
  only takes into account what the signature looks
  like.
• Dynamic signature verification takes into account
  how the signature was made.
• With dynamic signature verification it is not the
  shape or look of the signature that is
  meaningful, it is the changes in speed, pressure
  and timing that occur during the act of signing.
• Only the original signer can recreate the changes
  in timing and X, Y, and Z (pressure).

7
Signature Scan Introduction (Concluded)

• A pasted bitmap, a copy machine or an expert
  forger may be able to duplicate what a signature
  looks like, but it is virtually impossible to
  duplicate the timing changes in X, Y and Z
  (pressure).
• There will always be slight variations in a
  persons handwritten signature, but the
  consistency created by natural motion and
  practice over time creates a recognizable pattern
  that makes the handwritten signature natural for
  biometric identification.
• The primary advantage that signature verification
  systems have over other types of biometric
  technologies is that signatures are already
  accepted as the common method of identity
  verification.
• This history of trust means that people are
  willing to accept a signature based verification
  system.

8
Signature Scan (Process)

• The signature, along with the variables present
  during the signing process, is transmitted to a
  local PC for template generation.
• Verification can take place against a local PC or
  a central PC, depending on the application.
• In employee-facing signature-scan applications
  such as purchase order authentication, local
  processing may be preferred there may be just  a
  single PC used for such authorization.
• For customer-facing applications, such as retail
  or banking authentication, centralized
  authentication is likely necessary because the
  user may sign at one of many locations.

9
Signature Scan Process (Concluded)

• The results of signature-scan comparisons must be
  tied into existing authentication schemes or used
  as the basis of new authentication procedures.
• For example, in a transactional authentication
  scenario, the authorize transaction message
  might be sent after a signature is acquired by a
  central PC.
• When signature-scan is integrated into this
  process, an additional routine requires that the
  signature characteristics be successfully matched
  against those on file in order for the authorize
  transaction message to go forward.
• In other applications, the results of a
  signature-scan match may simply be noted and
  appended to a transaction.
• For example, in document authentication, an
  unsuccessful comparison may be flagged for future
  resolution while not halting a transaction.

10
Signature Scan Strengths

• Because of the large amount of data present in a
  signature-scan template, as well as the
  difficulty in mimicking the behavior of signing,
  signature scan-technology is highly resistant to
  imposter attempts.
• Signature-scan also benefits from its ability to
  leverage existing processes and hardware, such as
  signature capture tablets and systems based on
  public key infrastructure (PKI)
• Since most people are accustomed to providing
  their signatures during customer interactions,
  the technology is considered less invasive than
  some other biometrics.

11
Signature Scan Weakness

• Signature-scan is designed to verify subjects
  based on the traits of their unique signature.
• As a result, individuals who do not sign their
  names in a consistent manner may have difficulty
  enrolling and verifying in signature-scan.
• During enrollment subjects must provide a series
  of signatures that are similar enough that the
  system can locate a large percentages of the
  common characteristics between the enrollment
  signatures.
• During verification enough characteristics must
  remain constant to determine with confidence that
  the authorized person signed.
• As a result, individuals with muscular illnesses
  and people who sometimes sign with only their
  initials might result in a higher False Rejection
  Rate

12
Signature Scan Applications

• Signature-scan is implemented in situations where
  signature or written input processes are already
  in place.
• These applications include contract execution,
  formal agreements, acknowledgement of services
  received, access to controlled documents, etc. 
• As the act of signing documents becomes more
  integrated with electronic capture processes -
  signing on acquisition tablets - the opportunity
  for biometric authentication will increase
  dramatically.
• Note that signature-scan is not the same as
  digital signatures, an encryption technology.

13
Signature Scan Market

• Though it is one of the least frequently deployed
  technology in the biometric market today,
  signature-scan usage will increase, as a
  complement to static signature capture,
• Though a handful of vendors sell signature-scan,
  these firms will need to show the success of the
  technology in more high-profile settings.
• As applications for contract execution, formal
  agreements and access to controlled documents are
  demonstrated, signature-scan revenues are
  projected to grow from 3.0m in 2000 to 101.1m
  in 2005.
• Signature-scan revenues are expected to comprise
  approximately 5 of the entire biometric market.

14
Keystroke Dynamics Introduction

• Keystroke dynamics, also referred to as typing
  rhythms, is considered one of the most unusual
  and innovative biometric technologies. 
• It is considered a fairly new biometric
  technology and is still under development
• Studies have been conducted by the National
  Science Foundation as well as the National
  Institute of Standards and Technology with
  regards to a person's typing pattern. 
• Both the National Science Foundation and the
  National Institute of Standards and Technology
  have found typing patterns to contain unique
  characteristics that can be identified

15
Keystroke Dynamics Process

• Keystroke dynamics looks at the way a person
  types at a keyboard. 
• Specifically, keyboard dynamics measures two
  distinct variables "dwell time" which is the
  amount of time you hold down a particular key and
  "flight time" which is the amount of time it
  takes a person to between keys.  
• Keyboard dynamics systems can measure one's
  keyboard input up to 1000 times per second.
• Keystroke dynamics requires, as with most
  biometric technologies, a "reference template". 
  This involves several sessions of a person using
  a keystroke dynamic system so that the system can
  construct or build the "reference template" by
  detecting one's typing rhythms.

16
Keystroke Dynamics Strength

• Keystroke dynamics is behavioral in nature.  It
  works well with users that can "touch type". 
• Key advantages in applying keyboard dynamics is
  that the device used in this system, the
  keyboard, is unintrusive and does not detract
  from one's work. 
• Enrollment as well as identification go
  undetected by the user.  Another inherent benefit
  to using keystroke dynamics as an identification
  device is that the hardware (i.e. keyboard) is
  inexpensive.
• Currently, keystroke dynamics systems can be
  represented by plug-in boards, built-in hardware
  and firmware, or software.
•  Keystroke dynamics dynamics technology is an
  ideal solution for computing industry since the
  employee is already using the keyboard on a
  consistent basis. 

17
Keystroke Dynamics Weakness

•  Currently, keystroke dynamics has technical
  issues that must be addressed before it becomes
  widespread. 
• One technical issue is the standardization among
  computer keyboards and the lack thereof.  
• Standards among keyboards must be resolved as
  well as communication protocol structures before
  keystroke dynamics can successfully enter the
  marketplace. 
• To date, there have been a half dozen efforts to
  bring keystroke dynamics to commercial markets
  and most have failed