Biometric Authentication

Biometric authentication is an authentication mechanism that allows a user to perform a biometric scan to operate an entry or access system.

Physical characteristics stored as a digital data template can be used to authenticate a user
Typical features used include:
- facial pattern, iris, retina, fingerprint pattern, and signature recognition
fingerprint recognition
- most widely implemented
- relatively inexpensive and the process quite straightforward
- usually implemented as a small capacitive cell or optical camera that can detect the unique pattern of ridges making up the pattern
- nonintrusive and relatively simple to use
  - moisture or dirt can prevent readings
facial recognition
- records multiple indicators about the size and shape of the face
  - distance between the eyes or the width and length of the nose
- scan usually uses optical and infrared cameras or sensors
  - to defeat spoofing attempts that substitute a photo for a real face

Setting Up Biometric Authentication

First step is enrollment:
1. A sensor module acquires the biometric sample from the target
2. A feature extraction module creates a template
  - template is a mathematical representation of the parts of the sample that uniquely identify the target
when the user wants to access a resource,
- they are re-scanned
- scan is compared to the template
- If they match to within a defined degree of tolerance,
  - access is granted

False rejection rate (FRR)
- is where a legitimate user is not recognized
- referred to as a Type I error or false non-match rate (FNMR)
- measured as a percentage
- causes inconvenience
False acceptance rate (FAR)
- an interloper is accepted
- aka Type II error or false match rate (FMR)
- measured as a percentage
- can cause security breaches
- most important metric
Crossover error rate (CER)
- the point at which FRR and FAR meet
- aka equal error rate (ERR)
- lower the CER, the more efficient and reliable the technology
- Errors are reduced over time by tuning the system
  - accomplished by adjusting the sensitivity of the system until CER is reached
Throughput (speed)
- the time required to create a template for each user and the time required to authenticate
- major consideration for high-traffic access points
Failure to enroll rate (FER)
- incidents in which a template cannot be created and matched for a user during enrollment
Cost/implementation
- how expensive it is
- how easy/hard it is to implement
Psychological acceptability
- are users willing to accept this method
- can find it intrusive and threatening to privacy
- can be discriminatory or inaccessible to those with disabilities