Biometrics: Fingerprint Technology
Calvin Shueh Professor Stamp CS265 4/5/04 Living in the information age, individuals have vast amounts of information that they wish to keep private. Much of this information is protected by the use of passwords. Although this approach is satisfactory with most individuals, some seek more secure methods. One approach is using characteristics of individuals as the form of authentication, known as biometrics. Biometric security is based on something you know or have, and are. Fingerprints are the most common form of biometrics and have several measurable distinctive characteristics. The biometrics industry is growing fast because of new technology and the need for a more secure authentication system.
Although many individuals feel that passwords are enough to protect our information, there are several problems1. People often forget passwords or worse, they can be stolen and then used by other individuals. A person might have several different passwords used for different applications. Passwords are often poorly chosen because individuals incorporate personal information or use common dictionary words.
An alternative to passwords is using human characteristics for the purposes of identification; this is known as biometrics2. Because individuals have these distinctive features, they can be used as a form of identification3. According to a study, as many as
80% of the public has allowed a biometric feature to be recorded4. Although there are several human characteristics that can be measured for authentication including the face, eye, and voice, the fingerprint is the most commonly used characteristic5. Everyone is born with a fingerprint. They cannot be forgotten at home or left in the car. Fingerprints are the oldest form of biometrics that has been used successfully6.
In the 14th century, parents in China used the fingerprints and footprints of their children as a form of identification7. Since then, fingerprints have been studied and their characteristics have been catalogued. Each individual fingerprint is unique; everyone has an immutable fingerprint8. A fingerprint consists of several lines that produce patterns, called ridges, which can be used to verify and authorize an individual9.
The most common system used to classify the ridge patterns in fingerprints are known as the Galton features10. There are six classes of patterns. These are known as arch, tented arch, left loop, right loop, whorl, and twin loop. Each pattern has it’s own distinct design that distinguishes them apart. The several features that are classified are known as minutiae11. These are the irregularities in the otherwise smooth pattern of ridges in a fingerprint. The minutiae include characteristics called the crossover, core, bifurcation, ridge ending, island, delta, and pore12.
Figure 1 13
The crossover pattern is created when two different ridges cross each other. The point in which swirls or other patterns often center around is known as the core.
Bifurcation is the point at which one ridge separates into two separate ridges. A ridge ending is the end point of a ridge. An island is small ridge in the space between two other ridges and does not touch any other ridges. The space in between ridges where several ridges surround is known as a delta. Occurring inside ridges at steady intervals are pores14.
A device is used to capture an image of the pattern of an individual’s fingerprint.
There are two main technologies used to capture the image of the fingerprint. The first technology involves optical technologies using a prism in which a source of light is refracted15. Using this light, the device is able to take an accurate fingerprint image.
The second technology used is capacitive-based semiconductors. The fingerprint is obtained by having the subject place the finger on a sensor chip. The chip then detects capacitance changes between the ridges and valleys between the chip and skin and uses this to construct an image according to the variance of voltages16.
An example of an optical technology is the Advanced Minutiae Based Algorithm by Suprema Solutions. The algorithm uses two processes: the Feature Extractor and
Matcher17. When this image is captured, the extraction of the minutiae is known as
Feature Extractor; this serves as the core of fingerprint technology18. The Feature
Extractor will often need to enhance the image prior analysis19. Much of the features of the fingerprint caused by noise, poor contrast, and dirt can be removed by using a noise reduction algorithm20. This image is then processed using proprietary algorithms extract the minutiae and store or compare this information against a previously stored fingerprint in the database. Two of the most frequent features of the minutiae used in applications are the characteristics at ridge endings and points of bifurcation21 22.
Figure 2 23
During extraction of the minutiae several points of interest will be discarded due to distortion and false minutiae. A minutia might be discarded because it is too close to another minutiae24. This is because research shows that are very rarely adjacent to each other. There are several factors of a fingerprint that can be legitimate but be discarded by the extractor. If a finger has a scar that makes it appear that there is a ridge crossing several other ridges, this can result in a minutia that will be discarded. There will be between 30 and 60 minutia remaining after the extraction and cleanup25.
After extraction, there are several methods to store the information resulting from the remaining minutiae. One method is to use the core as the center point with coordinates (0,0) and determine the location of the remaining minutiae around the core26.
Another algorithm is to use the boundaries on the bottom and left as the axes for determining coordinates. Besides the coordinate, the angle of the minutia is also calculated and stored. The angle is calculated by using the horizontal line from the core using the right of the core as the zero degree angle27. The second part of the algorithm is the Matcher. This is the part of the application that will try and match the fingerprint that was obtained against fingerprints in a database. There is often a trade-off between speed and performance. Being able to quickly and correctly identify a fingerprint in the shortest amount of time possible with the high accuracy is an important factor28. A match can be made faster if the minutiae are grouped together and categorized by type. A fingerprint with a large number of a certain type of minutiae can be compared quicker to sorted results in the database by that characteristic29.
Fingerprint biometrics is often used for authentication and identification30.
Authentication is the process of verifying that the person is who they claim to be. This is done on a one-to-one comparison. This will return a positive result if the fingerprint matches a template in the system for whom the person claims to be31.
Identification is used to determine who the person is32. This is done with a one- to-many algorithm. By supplying the fingerprint, the system will scan entries in a database and if the fingerprint matches a result, it will identify the person as that result.
Otherwise, the system will not be able to identify the user until that information is stored in the database33.
On occasion, a false rejection may occur from the algorithm. On 97% of the occasions that an authorized user is able to use the device, it will return correctly34. The other 3% of the time, the user will have to rescan the fingerprint using the device.
However, the device can be 100% accurate in preventing intruders from using the system
35. Security is an important issue when dealing with information. Contrary to popular belief, the image of the fingerprint during the extraction is discarded36. Only an encrypted template of the fingerprint minutiae will be kept for storage. Using this information alone, it is not possible to reconstruct the fingerprint or gain enough information to create a fake fingerprint.
Several of the fingerprint biometric systems have sensors to determine that it is a live fingerprint37 38. This means that a person cannot use a severed finger from a person because the heartbeat sensor and temperature will not be correct39. There are several devices built into systems to prevent fake fingerprints. An example includes using a latent print residue to try and capture an individual’s fingerprint after the device has just been used40. Other factors used to detect for false fingerprints include detectors for temperature, pulse, and blood flow.
Biometrics using fingerprints is the most commonly used system for consumer biometric systems41. There are several factors for this success that include ease of integration, convenience, size, and the low cost of manufacturing42 43. Some devices where this is being used are keyboards44, wireless handheld devices45, and notebooks46.
Some other applications include smart cards47, web application authorization48, access control49, and safes50.
It has been shown that fingerprint biometrics has several advantages over other biometric technologies51. The technologies were compared by accuracy, convenience, cost and size using a scale of 1 (worst) through 5 (best). Table 1 clearly shows that fingerprint technology is the best overall biometric technology to be used for the main biometrics criteria used. Biometric Accuracy Convenience Cost Size
Technology Fingerprint 5 5 4 4 Voice 1 5 5 5 Face 2 3 4 3 Hand 3 3 2 2 Iris 5 2 3 3 Table 1 52
Industries that fingerprint biometrics are used include immigration53, welfare, law enforcement, banking, and access control54. With much of the world already using or currently adapting to fingerprint biometrics, the industry will grow at substantial rates 55.
In the past several years, biometric authentication has received a tremendous amount of funding and research. Of the biometrics used, fingerprints comprise 48% of the total market in 2004 56. Face recognition and middleware both have 12% market share followed by hand and iris at 11% and 9% respectively57. E-commerce and remote transactions should fuel the rapid growth of this technology58. According to the
Biometrics Market and Industry Report, the revenue was $719 million in 2003, and will continue to grow about 50% each year, reaching $4.6 billion in 2008 59.
Security has become a major problem over the years and more sophisticated authentication systems were desired. Individuals commonly use passwords to secure their information that they wish to keep private. However, if this password was stolen, it could be used to imitate them and gain access to the information; also, passwords are often forgotten. Biometrics eliminates the use of passwords by using human characteristics to authenticate a person. Fingerprint biometrics is the most commonly used system and is used in several industries worldwide. This is due to the accuracy, convenience, and cost of the technology and the uniqueness of fingerprints. The biometrics market will continue to grow in the coming years as new applications and devices are created. References 1 OnClick Corporation. “A Closer Look: Who’s Using Biometrics and Why” 2004 http://www.onclickbiometrics.com/ebusiness/ocbioweb.nsf/wContent/AboutBiometricsCloserLook?opendocument
2 OnClick Corporation. “What is Biometrics?” 2004 http://www.onclickbiometrics.com/ebusiness/ocbioweb.nsf/wContent/AboutBiometricshome?opendocument
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4 OnClick Corporation. “A Closer Look: Who’s Using Biometrics and Why” 2004 http://www.onclickbiometrics.com/ebusiness/ocbioweb.nsf/wContent/AboutBiometricsCloserLook?opendocument
5 id. 6 findBiometrics, “About Fingerprint Scanning” 2004 http://www.findbiometrics.com/Pages/fingerprint_articles/fingerprint_1.html
7 National Center for State Courts, “Fingerprint” http://ctl.ncsc.dni.us/biomet%20web/BMFingerprint.html
8 findBiometrics, “About Fingerprint Scanning” 2004 http://www.findbiometrics.com/Pages/fingerprint_articles/fingerprint_1.html
9 Suprema Solutions, “Fingerprint Technology” 2004 http://www.suprema.co.kr/technology.html
10 International Biometric Group, “Fingerprint Feature Extraction” 2004 http://www.biometricgroup.com/reports/public/reports/finger-scan_extraction.html
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15 McClure, Ron. “Biometric Solutions to Personal Identification” Digital Persona. 1998 http://www.heylookmeover.com/dp/html/press-info/RTF/Biometrics
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18 International Biometric Group, “Fingerprint Feature Extraction” 2004 http://www.biometricgroup.com/reports/public/reports/finger-scan_extraction.html
19 Suprema Solutions, “Fingerprint Technology” 2004 http://www.suprema.co.kr/technology.html
20 id. 21 findBiometrics, “About Fingerprint Scanning” 2004 http://www.findbiometrics.com/Pages/fingerprint_articles/fingerprint_1.html
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23 Suprema Solutions, “Fingerprint Technology” 2004 http://www.suprema.co.kr/technology.html
24 International Biometric Group, “Fingerprint Feature Extraction” 2004 http://www.biometricgroup.com/reports/public/reports/finger-scan_extraction.html 25 id.
26 id.
27 Id.
28 Suprema Solutions, “Fingerprint Technology” 2004 http://www.suprema.co.kr/technology.html
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30 Synaptics. “Fingerprint TouchPad: What is biometric authentication?” http://www.synaptics.com/products/fingerprint_faq.cfm
31 OnClick Corporation. “An Intro to Biometrics: Quick guide to 1-2-3 biometric process” http://www.onclickbiometrics.com/ebusiness/ocbioweb.nsf/wContent/AboutBiometrics123?opendocument
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36 OnClick Corporation. “An Intro to Biometrics: Quick guide to 1-2-3 biometric process” http://www.onclickbiometrics.com/ebusiness/ocbioweb.nsf/wContent/AboutBiometrics123?opendocument
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38 findBiometrics, “About Fingerprint Scanning” 2004 http://www.findbiometrics.com/Pages/fingerprint_articles/fingerprint_1.html
39 Parvus Corporation. “Fingerprint Biometrics Systems Development Platform” http://www.parvus.com/datasheet/DS.asp?PrimaryPart=APP-0148X-01
40 findBiometrics, “About Fingerprint Scanning” 2004 http://www.findbiometrics.com/Pages/fingerprint_articles/fingerprint_1.html
41 id. 42 Id.
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45 findBiometrics, “Fingerprint Form Factors” 2004 http://www.biometricgroup.com/reports/public/reports/finger-scan_form_factors.html
46 The Journal. “Fingerprint Biometrics Delivers Greater Computer Protection” 2004 http://www.thejournal.com/magazine/vault/A4628.cfm
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49 General Masters, Inc. “iGuard: How it works – as an Access Control System” http://www.gmasterinc.com/access-control/iguard/applications.htm
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55 Canadian News Wire. “CTF Introduces Biometric Authorizatoin for Fuel Purchases in Brazil” http://www.newswire.ca/en/releases/archive/February2003/03/c5767.html
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