Chapter OneIntroduction to Biometrics

1.1 Biometrics Definition

Biometrics: is the application of statistical analysis to biological data.

Biometrics refers to the identification of humans by their characteristics or

traits. Biometrics is used in computer science as a form of identification and

access control.

It is also used to identify individuals in groups that are under

surveillance. Biometric identifiers are the distinctive, measurable

characteristics used to label and describe individuals. Biometric identifiers are

often categorized as physiological versus behavioral characteristics.

Physiological characteristics are related to the shape of the body.

Behavioral characteristics are related to the pattern of behavior of a

person.

1.2 Biometrics History

Biometrics is the application of statistical analysis to biological data. In

the 21st century, it seems almost intuitive to think of our bodies as natural

identification systems for our unique selves. In fact, the idea that our bodies,

eyes, faces and fingers might give us (and criminals) away developed over

time, through the work of many people.

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Chapter one: introduction to Biometrics

19th Century:

Anthropometry Develops Others date the origins of biometrics to

Alphonse Bertillon. He was a member of the police was working as a record

clerk in his native Paris when he invented anthropometry in the late 19th

century: the use of body measurements to identify criminals.

Bertillon's system also involved recording suspects' body movements

and marks on their bodies, such as warts or tattoos. Both American and British

police forces used this system, which came to be called Bertillonage, to narrow

the number of suspects they sought. However, measurements could not be

made exactly and different officers always measured slightly differently 

Late 19th Century:

Fingerprinting Begins. There are many steps in the history of

fingerprinting as a way to identify criminals. Bertillon included fingerprinting

in his system, but not as an important element. An Argentine police official

was the first person to keep fingerprint files.

He classified fingerprints according to a system established by Sir

Francis Galton, an anthropologist related to Charles Darwin. Galton later

published a book, Fingerprints, that contained a classification system. His

discovery that no two individuals share the same fingerprint, and his

classification of the details of an individual's fingerprint are largely used today.

By the 1920s, fingerprint identification was used by law enforcement.

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Chapter one: introduction to Biometrics

Figure(1-1) : Fingerprint

Late 20th Century: Automated Biometric Techniques

Although finger printing is still in use today, computer aided techniques

began developing—rapidly—in the last quarter of the twentieth century. These

techniques sought to measure our voices, our hands, fingers, irisis and faces.

Once ideas were proposed, development was rapid. For example, in 1985, the

idea that irises are unique was proposed; development of an iris identification

system began in 1993; in 1994 the first iris recognition algorithm was patented,

and the year after that, a commercial product measuring irises became

available. Iris scanners have already been tested as supplements in security

contexts in a number of countries, as well as in commercial contexts.

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Chapter one: introduction to Biometrics

1.3 How Biometrics Work

Biometric technology must first gather information into a computer

database, for example, a database of fingerprints. The computer will compare

the fingerprints in the database to any new sample and recognize when there is

a match. The matches can be used for either identification or verification

purposes.

Biometric Identification

A biometrics system searches the database for a match to the newly

captured sample, and grants access if it is found. Using a fingerprint as part of

the login process to a computer is an example of this mode.

Biometric Verification

A biometrics system searches the database for a match to the newly

captured sample, and authenticates an individual's claimed identity from his or

her previously enrolled pattern. Using a palm scanner to unlock a door is an

example of this mode.

1.4 Uses of Biometrics

Biometrics has long being touted as a powerful tool for solving

identification and authentication issues for immigration and customs, physical

security, and computer security. It involves measuring one or more unique

physiological human characteristics, the shape of a body, fingerprints, structure

of the face, DNA, hand/palm geometry, iris patterns, and even odor/scent.

Behavioral traits can also be used – typing rhythm, gait, and voice.

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Chapter one: introduction to Biometrics

These technologies have enormous promise because they can never be

forgotten, lost or copied, unlike the current methods of cards and passwords

Biometrics are seductive. Your voiceprint unlocks the door of your house.

Your iris scan lets you into the corporate offices. You are your own key.

Unfortunately, the reality isn't that simple.

Biometrics are the oldest form of identification. Dogs have distinctive

barks. Cats spray. Humans recognize faces. On the telephone, your voice

identifies you. Your signature identifies you as the person who signed a

contract.

In order to be useful, biometrics must be stored in a database. Alice's

voice biometric works only if you recognize her voice; it won't help if she is a

stranger. You can verify a signature only if you recognize it. To solve this

problem, banks keep signature cards.

Alice signs her name on a card when she opens the account, and the

bank can verify Alice's signature against the stored signature to ensure that the

check was signed by Alice.

There is a variety of different biometrics. In addition to the three

mentioned above, there are hand geometry, fingerprints, iris scans, DNA,

typing patterns, signature geometry (not just the look of the signature, but the

pen pressure, signature speed, etc.). The technologies are different, some are

more reliable, and they'll all improve with time.

Biometrics are hard to forge: it's hard to put a false fingerprint on your

finger, or make your iris look like someone else's. Some people can mimic

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Chapter one: introduction to Biometrics

others' voices, and Hollywood can make people's faces look like someone else,

but these are specialized or expensive skills. When you see someone sign his

name, you generally know it is he and not someone else.

On the other hand, some biometrics are easy to steal. Imagine a remote

system that uses face recognition as a biometric. In order to gain authorization,

take a Polaroid picture of yourself and mail it in. We'll compare the picture

with the one we have in file.'' What are the attacks here?

Take a Polaroid picture of Alice when she's not looking. Then, at some

later date, mail it in and fool the system. The attack works because while it is

hard to make your face look like Alice's, it's easy to get a picture of Alice's

face. And since the system does not verify when and where the picture was

taken--only that it matches the picture of Alice's face on file--we can fool it.

A keyboard fingerprint reader can be similar. If the verification takes

place across a network, the system may be unsecure. An attacker won't try to

forge Alice's real thumb, but will instead try to inject her digital thumbprint

into the communications.

The moral is that biometrics work well only if the verifier can verify

two things: one, that the biometric came from the person at the time of

verification, and two, that the biometric matches the master biometric on file. If

the system can't do that, it can't work. Biometrics are unique identifiers, but

they are not secrets. You leave your fingerprints on everything you touch, and

your iris patterns can be observed anywhere you look.

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Chapter one: introduction to Biometrics

Biometrics also don't handle failure well. Imagine that Alice is using

her thumbprint as a biometric, and someone steals the digital file. Now what?

This isn't a digital certificate, where some trusted third party can issue her

another one. This is her thumb. She has only two. Once someone steals your

biometric, it remains stolen for life; there's no getting back to a secure

situation.

And biometrics are necessarily common across different functions. Just

as you should never use the same password on two different systems, the same

encryption key should not be used for two different applications. If my

fingerprint is used to start my car, unlock my medical records, and read my

electronic mail, then it's not hard to imagine some very unsecure situations

arisin.

Biometrics are powerful and useful, but they are not keys. They are not

useful when you need the characteristics of a key: secrecy, randomness, the

ability to update or destroy. They are useful as a replacement for a PIN, or a

replacement for a signature (which is also a biometric). They can sometimes be

used as passwords: a user can't choose a weak biometric in the same way they

choose a weak password.

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Chapter one: introduction to Biometrics

1.5 Advantages of Biometric Technologies

Enhanced security was thought to be the greatest benefit of biometric

technologies, followed by accuracy. Other benefits were its unique feature of

not being shared/copied/lost, it reduces paperwork, and it is convenient. On the

other hand, the greatest disadvantage was possible invasions of privacy,

followed by the financial costs to implement.

Figure (1-2): Advantages of Biometric Technologies

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Chapter one: introduction to Biometrics

1.6 Disadvantages of Biometric Technologies

While biometric technologies are on the upswing and their use is

becoming widespread because of the advantages we have outlined above,

biometric technologies also have some disadvantages. Such as

Limitations: Because these technologies apply to human beings, they

are affected and are limited by many situations that may affect the individual.

For example, fingerprint technology may not be effective if the subject has

dirty, deformed, or cut hands; iris technology may not be effective if the

subject has a bad eye; and voice technology may be affected by infections.

Also background noise can interfere with voice recognition systems.

Affordability (high cost): Because biometric technologies are new

technologies, they tend to be rather expensive without widespread use. For

example, facial and voice recognition and iris technologies are still not yet

affordable.

Cannot replace a biometric that has been lost or misappropriated.

Once a biometric has been compromised, it cannot be made right again.

Biometrics evolve and degrade over time and require constant updates

of the reference biometric.

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Chapter one: introduction to Biometrics

Figure (1-3): Disadvantages of Biometric Technologies

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