Putting a finger on it – the loops and whorls of biometricsAutomated measurement techniques to verify a person’s identity are attracting widespread attention. In Australia, Woolworths and the banking industry are already using fingerprint identification technology.
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Key textJames Bond has known about it for years. Charlie’s Angels are also up to speed, as is the team at Mission Impossible. But for the rest of us, the idea of using fingerprint scans or iris scans to gain access to restricted places or information is still a well-kept secret.But maybe not for long. Biometrics could be coming to a scanner near you! Defining biometrics People have always used individual traits for identification. In ancient times, the presence of scars, birthmarks and other unusual features helped minimise mistaken identify. Even today, we use techniques that have been around for centuries, such as passwords and signatures. But passwords are notoriously insecure, and signatures can be forged or ignored. Shop assistants, for example, often don’t bother to compare the signature on the back of a credit card with the sample provided by the purchaser. The search is on for better ways of proving identity. As computer power has grown, so too has the idea that the automated capture, measurement and identification of distinctive physiological or behavioural characteristics could safeguard our identities and therefore our property and privacy, and could also be used to fight crime. The technologies now being developed for these purposes have come to be labelled 'biometrics', because they apply statistical methods to biological observations and phenomena. However, the discipline of biometrics is much broader than just identity verification. Biometrics plays a crucial role in agriculture, environmental and life science. Fingering the issue The most well-known biometric technology of all is the fingerprint – we all know that the biggest mistake a criminal can make is to leave a fingerprint at the scene of the crime. If you look closely at the underside of your fingertips you’ll see dozens of swirling lines. These are made by minute, raised ‘friction ridges’ on the skin; their purpose is to give your fingers better grip in the way that car or bike tyres have ‘tread’ to keep them from skidding on the road. You can see similar friction ridges on the palms of your hands and the soles of your feet. The friction ridges form several macro-patterns, the three most common of which are the arch, loop and whorl. Individual ridges also have distinctive variations, known as minutiae. These include:
The arrangement of the ridges and their minutiae on the finger is random: probability theory suggests that the chance of two fingers having exactly the same arrangement is more than a billion to one. Indeed, in a hundred years of the systematic fingerprinting of criminal suspects and more than 100 million fingerprints later, no two have ever been found to be identical. Fingerprints are fully formed in the womb and remain unchanged throughout life. In Australia, the use of fingerprinting in fighting crime was recently updated under the CrimTrac system. But it is not only the police who are excited about fingerprint biometric technologies: ideas for applying them commercially (eg, to control access to personal computers) are coming almost as fast as you can push a button. The difference between identification and verification The use of biometric technologies against crime mostly involves identification; whereas verification is more common in commercial uses. The difference between the two can be shown in the following examples. Imagine an automatic teller machine (ATM) that uses a fingerprint instead of a number as a password. The machine confirms your identity by comparing your fingerprint with the ‘reference’ fingerprint originally encoded into the card. That’s verification. If a thief breaks into a house, he might leave behind a fingerprint. The question the police want to answer is: who does this fingerprint belong to? It can be checked against a database of criminal fingerprints; finding a match is identification. In terms of computing power, the difference between verification and identification is important: comparing the fingerprint entered by the user with the reference fingerprint (verification) is a simple task. Matching a fingerprint with all those contained in a database of thousands or even millions (identification) requires considerable computer grunt. In most commercial applications of biometrics, the aim is to verify the identity of the user. Finger scanning The potential applications of using fingerprints are being made possible by the development of automated finger scanning. Up until a few years ago, fingerprints were collected in the way we see in police movies: put the finger on an inkpad, then place it carefully on a sheet of paper. In the last decade or so, electronic scanners have been used to digitise the old, paper-based prints to form an electronic database. Now, technologies to scan the finger directly are developing rapidly. Optical finger-scanners, which work in a similar way to a photo scanner, have been in use for a decade or so and are starting to be replaced by other methods. One of these is called capacitive scanning: it measures the electrical charge produced by the contact of the fingertip with an array of tiny capacitors mounted onto a silicon microchip. Since the ridges will make better contact with the capacitors than the valleys, this technique generates an image of the fingerprint that can be processed in the same way as an image produced by optical scanning. Ultrasound finger-scanners are also being developed. Once the fingerprint image has been obtained it needs to be measured. In one approach, a computer algorithm – a program designed to turn raw data into code that can be used more easily by the identification/verification software – identifies minutiae points on the scanned print and ‘locates’ them relative to other points on the print. It then establishes a mathematical ‘template’ to serve as a reference. When the same finger is scanned at a later time – perhaps when its owner wants to use an ATM – the computer software compares the template, which could conceivably be stored on a microchip in the user’s card, with the newly scanned print. Applications of finger scanning Fingerprint verification is already being used – on a limited basis so far – to control access to personal computers, cell phones and ATMs. A quick search of the internet reveals a host of companies selling finger scanning devices and citing very low ‘false rejection’ rates and even lower ‘false acceptance’ rates. Techno-visionaries predict applications for finger scanning far wider than merely access to the laptop or ATM. They foresee a time when the right finger in the right place will unlock car doors, open briefcases, verify identity over the internet, facilitate travel across international borders and prevent voter fraud. But sceptics point to potential shortcomings. For example, fingerprinting has criminal connotations that will turn many law-abiding people away and some consumer resistance seems inevitable. Others worry that it could even provoke a wave of violent ‘finger snatching’, because possessing someone else’s fingerprint could be extremely lucrative. The eyes have it Meanwhile, technology companies continue to invest research dollars in other biometric options. Iris and retina scanning seem to have considerable potential: the patterns in both these parts of the eye are unique to the individual. The retina is the innermost layer of the eyeball ‘wall’ and is criss-crossed by tiny blood vessels. As these vessels develop in the womb, they form a unique pattern that does not change over the individual’s lifetime; retina scanning can map, code and compare these blood vessel patterns. The iris, the coloured part of the eye, contains about 260 unchangeable characteristics – compared to less than 40 in fingerprints – that can be scanned by video camera, coded by algorithms and, later, compared. The chance of an identical match with a different eye is said to be about 1 in 1078, which is a very small chance indeed. Of the two eye-scanning technologies, iris-scanning is the more likely to gain in popularity. It can be done at a distance of a metre or so – in contrast to retina-scanning, which must be done quite close-up – and is therefore likely to be more acceptable to the public. Other biometric tools We all have other unique characteristics that can be measured. Examples of these other biometric options include hand geometry, typing patterns and voice recognition (Box 1: Other biometric technologies for identity verification). Privacy issues Biometrics-based identification and verification systems must deal with a host of privacy issues if they are to gain widespread acceptance. For some, the prospect of submitting body parts for detailed examination is enough to make them break out in a sweat, while amputees or the blind may not find certain biometric systems to be particularly user-friendly. Meanwhile, some people worry that biometric data given for an innocent purpose, such as opening a bank account, will be used for other, more sinister purposes by governments or corporations. Another concern is the potential ‘hijacking’ of biometric data – if transmitted over the internet, for example – by criminals who would then use it to defraud individuals and institutions. Such arguments must be weighed against the fact that the aim of most biometric systems is to increase privacy by requiring a more rigorous proof of identity than has been necessary in the past. If the system is robust enough, criminals will find that beating it is a difficult task. Nevertheless, the technologies present civil libertarians with many issues that must eventually be addressed.
The future?
Biometric systems face another crucial question: supposing they do bring an increase in security, will it be worth the financial cost? Advocates say the answer to this question is increasingly ‘yes’ and that the role of biometric technologies in our lives will grow quickly. But if the sceptics are right and such enthusiasm is not yet warranted, James Bond and his peers in the police forces may remain the biggest users of the technologies for some time yet.
Hand geometry Since the exact shape of the hand and the relative lengths of the fingers and thumb vary between individuals, hand geometry is touted as a potentially useful biometric. The advantage of hand scanning over fingerprinting is that it is less invasive, very user-friendly and requires little computer firepower. The drawback is that hand shapes are not unique, so hand geometry biometric technology is likely to be limited to low-security applications. Typing patterns Another kind of biometric technology looks at behavioural characteristics. Most of us possess certain patterns of behaviour that are unique to us. Keyboard recognition technology assesses the typing style of the user. It determines dwell time (the time that each key is depressed), flight time (the time taken to move between keys), and a host of other characteristics, such as typical typing errors. An algorithm codes these patterns. When the computer is used at a later time, the software compares the user’s typing pattern against the template. If the variation is above a threshold, thereby indicating that an imposter is using the computer, the software denies access to restricted material. Other technologies are under development Many other biometric technologies for identity verification are under development, including voice recognition, face recognition (systems are now being developed to assist police and security agencies to identify suspects in crowds), vein measurement, chemical odour analysis, signature identification and facial thermography (the measurement of the radiant heat from a person’s face). Some could be combined in multi-biometric systems, so that the limitations of any single system can be compensated by the presence of a second or third system. Related sites
Australasian Science July 2007, page 7 Forgery protection lights up fingerprinting Looks at the potential use of anti-Stokes materials in fingerprinting.
Australian Science Teachers' Journal September 2003, pages 34-39 The science of biometric identification (by Clifton L. Smith) Covers different methods of identifying individuals using biometric characteristics and suggests classroom activities that could be developed.
Issues June 2005, pages 4-8 Privacy and new technology (by the Office of the Privacy Commissioner) Looks at information privacy issues associated with new technologies.
June 2005, pages 23-24 Genetic privacy (by Loane Skene) Discusses new genetic technologies and questions about confidentiality of medical information.
New Scientist 19 September 2007, page 30 Online biometrics flaw gives hackers a ‘fake finger’ (by Anil Ananthaswamy) Looks at a scheme which could allow hackers to steal the fingerprint data.
3 June 2006, page 28 The code that keeps your fingerprints secure (by Celeste Biever) Discusses a new way to store fingerprints, iris scans and facial images.
7 January 2006, page 22 Fake fingers no match for scanner's electronic nose (by Celeste Biever) Explains what scientists are doing to overcome fake finger scans.
19 September 2005, page 6 How far should fingerprints be trusted? (by Andy Coghlan and James Randerson) Looks at the reliability of fingerprints as evidence in court cases.
13 September 2005, pages 26-29 ID revolution – prepare to meet the new you (by Celeste Biever) Looks at the growing dependence on digital information to establish identity.
17 September 2005, pages 20-23 Privacy and prejudice: Whose ID is it anyway? (by Duncan Graham-Rowe) Discusses the issue of biometrics and privacy.
14 July 2005 Ear biometrics may beat face recognition (by Duncan Graham-Rowe) Describes ear-shape analysis as a means of identifying people.
9 April 2005, page 4 Finger chopped off to beat car security Describes the actions of car thieves who stole a car with a fingerprint recognition ignition system.
19 May 2004 New biometric approach secures ID cards (by Duncan Graham-Rowe) Describes a system of iris scanning that does not need reference scans to be stored on a central database.
13 March 2004, pages 6-7 Bite-mark evidence can leave a false impression (by James Randerson) Discusses the reliability of teeth bite marks as evidence in court.
31 January 2004, pages 6-7 Forensic evidence stands accused (by James Randerson and Andy Coghlan) Discusses the reliability of fingerprints as evidence in court.
21 November 2003 Biometric cards will not stop identity fraud (by Duncan Graham-Rowe) Looks at the possibility of obtaining fraudulent biometric identity cards.
7 September 2002, pages 38-42 Face-off (by Michael Brooks) Looks at face-recognition software.
RTD Info August 2005 The boundaries of surveillance Asks how the need for security can be reconciled with the freedom of the individual.
August 2005 Biometrics and justice Looks at the need for secure communication transactions in the field of justice. Includes boxed information 'Benefits of the match-on-card' and 'Body prints'.
Scientific American 19 August 2008 Beyond fingerprinting: Is biometrics the best bet for fighting identity theft? (by Anil K. Jain and Sharath Pankanti) Describes security systems based on anatomical and behavioural characteristics.
July 2002, page 8-9 Who's who (by Paul Wallich) Looks at whether digital technology makes it more difficult to create a false identity.
Provides an overview of different biometric techniques.
Australian Broadcasting Corporation
Biometrics 101 (Biometrics Task Force, US Army)
A step by step tutorial on biometric technologies.
How Stuff Works, USA
An overview of biometrics (Department of Computer Science and Engineering, Michigan State University, USA) From this overview you can select more information about specific areas of biometrics (eg, fingerprint identification, speaker recognition, hand geometry).
Fingerprint analysis – the basics (CrimTrac, Australia) Uses a labelled diagram to explain different fingerprint characteristics (eg, ridge endings, spurs). Also covers the principles of fingerprint identification and points of similarity for fingerprint matching.
Biometrics: Your body is your password (Biometrics Australia) An overview of the different measurements that can be used in biometrics, and what is currently available for use in the business world.
algorithm. A logical, step-by-step procedure used to solve problems in mathematics and computer programming. In the case of biometrics the algorithm refers to a computer program designed to turn raw data into code that can be used more easily by identification/verification software. biometrics. The application of statistical methods to biological observations and phenomena. capacitor. A device for storing electrical energy. For more information see How capacitors work (How Stuff Works, USA). CrimTrac. Australia's major national policing initiative. CrimTrac includes the National Automated Fingerprint Identification System, and a National Criminal Investigation DNA Database. For more information see About us (CrimTrac, Australia) digitise. To transcribe data into a digital form (represented as a series of numerical values) so that it can be directly processed by a computer. microchip. This is a very small computer in the form of a silicon chip. It is normally put together with other items to produce a finished piece of equipment. For more information see Jack St. Clair Kilby – inventor of the microchip (Massachusetts Institute of Technology, USA).
External sites are not endorsed by the Australian Academy of Science. Posted October 2001. The Australian Foundation for Science is also a supporter of Nova.
This topic is sponsored by the Australian Government's National Innovation Awareness Strategy.
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