Fingerprint Scanners By: Jason Batchelor

Transcription

1 Fingerprint Scanners By: Jason Batchelor Professor: Anthony Vodacek Section: Date: of 7

2 Table of Contents: Introduction...3 History...3 Why Do We Use Them...3 How Do They Work...4 Security Limitations...5 Pros and Cons...6 Conclusion...6 Bibliography of 7

3 Introduction Physical security is one of the most fundamental and primary protection mechanisms when it comes to equipment, infrastructure, and classified information. When it comes to preventing unauthorized intrusion in a controlled area, many companies and agencies have turned to biometric identification devices like the fingerprint scanner to provide this type of protection. Their historical background, necessity in providing physical security, inner workings, possible limitations, and future implementations are an important part of ones understanding of this technology. History Ancient archeological artifacts and historical items have been discovered to still retain a large number of fingerprints on them. Since this was discovered significant strides in fingerprinting and identification have been made. In 1788 a detailed description of anatomical formations of fingerprints was made. Then in 1823 fingerprints began to be classified into nine categories, (Handbook) and by the 19 th century Sir Francis Galton had developed analytical methods for fingerprint matching. As the criminal justice system evolved, there arose the need for criminals to be uniquely identified by some physically identifiable trait. Richard Edward Henry of Scotland Yard began using fingerprinting in 1901 and its success eventually lead to its increased use in the law enforcement field (Handbook). The field of biometrics was formed and has since expanded on to many types of physical identification. Still, the human finger print remains a very common identifier and the biometric method of choice among law enforcement. These concepts of human identification have lead to the development of fingerprint scanners that serve to quickly identify individuals and assign access privileges. The basic point of these devices is also to examine the fingerprint data of an individual and compare it to a database of other fingerprints. Government agencies were the first to adopt this new technology, followed by private industries, and companies. Only now, has fingerprint scanning technology been made available to the everyday consumer in a usable form. Fingerprinting devices can be found in a standard computer mouse, notebook computers and standalone peripherals. Why Do We Use Them Nearly everyone in the world is born with a fingerprint that is unique; a separate and comprehensively identifying attribute that sets us apart from the other 6.5 billon people that inhabit this world. It is because of this fact that the fingerprint has proven such a useful part of biometric security. The very reason that fingerprint scanners are useful can be found in this fact as well. However, this is far from the only reason they are used. 3 of 7

4 Another important reason fingerprint scanners are used is, they provide a quick, easy, efficient, and secure measure through which, an individual with the proper access privileges can authenticate. The fingerprint of an employee for example, is stored in a database that the scanner queries every time it is used. There are two basic Boolean conditions the scanner then goes through when an individual s print is scanned. First, the print is usually searched for in a database of fingerprints, once it is found it then looks at the print to see what access privileges are associated with the print and compares them to the access they are trying to gain. If everything checks out the subject is allowed access and they are not otherwise. In any case, a log of the event is usually stored for security purposes (Doubt Cast). The size of these devices is another reason they have become so mainstream recently. Fingerprint scanners can be deployed directly near a door for access or as a peripheral to a computer for logging in. Modern day scanners have even been embedded on computer keyboards, mice, and USB devices because engineers have been able to reduce their size. Fingerprint scanners are also very versatile in the function that they can serve. The most common use may be for access restriction; however, they have served as time clocks, personal data retrievers, and even to cut down on truancy in some schools. Since they have experienced so much success in these areas, businesses are expanding upon their use and they are getting more public exposure (Do You Know). All of these reasons listed have helped contribute to the fingerprint scanner s success in our modern society. The robust physical security that it provides, combined with the sheer ease of use, and versatility make it a great choice if biometric identification is needed. This is why our law enforcement and government agencies have begun to use fingerprint scanners and continue to use fingerprints as a tell tale sign of proper identification. How Do They Work A fingerprint scanner system serves two different functions; first it needs to get an image of your fingerprint, then it needs to determine whether the patterns and ridges in your fingerprint match pre-scanned prints in its memory. Optical scanning and capacitance scanning are the two most commonly used methods by fingerprint scanners today to get a fingerprint image. Optical scanners use a charge coupled device (CCD) in order to grab the image. The CCD is the same light sensor system used in digital cameras. It contains an array of light sensitive diodes named photosites. Each of these photosites represents and records a single pixel measuring the amount of light that hit that spot (Do You Know). These light and dark images are combined to form a scanned image of the fingerprint. An analog to digital converter is then used within the scanner to create a digital fingerprint image (How Fingerprint). The whole scanning process beings when you place your finger on the scanner and the CCD camera takes a picture. An internal light-emitting device within the scanner shows the ridges of the finger, and an inverted image is 4 of 7

5 generated of the print. Dark parts of the image represent the ridges of the finger and lighter areas represent the valleys between the ridges. Before the scanned image is passed on to be evaluated, the processor makes sure that the image that was captured was a clear, sharp, and readable image. It does this by calculating the average pixel darkness in a small sample, if the image is too dark or too light it is rejected, the CCD adjusts its exposure time accordingly, and tries again (How Fingerprint). The capacitive scanner operates a bit differently. Even though the capacitive scanner generates an image of the fingerprint like the optical scanner, capacitive scanners do not use light to capture it, they use electrical current. An insulating layer makes up the surface of the scanner and the finger is pressed up against it. The insulating layer consists of many tiny conductor plates. Two of these conductor plates are joined together to form a capacitor that can store an electrical charge. The finger being pressed upon the insulating layer acts as a third capacitor plate. Once this is done the processor calculates the amplifiers output. Since the distance to the finger alters capacitance, a finger ridge will result in a different amplified output than a finger valley (How Fingerprint). It is because of this property that an image of a finger can be properly generated. The scanner reads that amplifiers output that the processor generated and determines whether it is a ridge part of a fingerprint or a valley. Once all the cells are read an image can be formed of the fingerprint. The main advantage of this is that a real fingerprint is required to activate the system which makes it much harder to trick, which will be discussed later. After the image is processed by using the optical or capacitance method, an analysis is performed on the image. Fingerprint scanners do this by comparing certain specific features of a print to another. This is referred to by professionals as minutiae (Do You Know). The software that does this uses a very complex algorithm in order to do this however; the main idea is measuring the relative positions of the minutiae in comparison with other prints. If the software finds that the measurements in two prints are the same, there s a strong possibility they are the same print. Even with this strong possibility, people have developed ways to subvert these scanning systems. Security Limitations In December 15 th 2005, Clarkson University released a study claiming that they could fool ninety percent of fingerprint scanners with a childhood favorite toy. They managed to compromise the security of some of the most complicated fingerprint scanning devices in the world using Play-Doh. They created a mold of the marks fingerprint and then pressed Play-Doh into it to obtain a replica fingerprint. When this replica was pressed against a vulnerable fingerprint scanner it was fooled into thinking it was the marks actual finger. The Clarkson team is not the only ones to fool fingerprint scanners (Play-Doh Fingers). On September 21 st 2006, the Mythbusters beat another type of fingerprint scanner that measured finger pore sweat, simply by licking the latex replica of an 5 of 7

6 authorized fingerprint. The manufacturer maintained beforehand that their print system had never been defeated (Beat a Fingerprint). Since these incidents, scanner manufacturers have been developing new methods and ways to fine tune fingerprint scanning. The philosophy seems to be the more detailed they can get the better. There are now systems that are in production that not only scan your fingerprint and sweat amount, but also take a measurement of the subjects pulse (Doubt Cast). The more barriers that are put in front of a criminal trying to break a system, the harder it becomes to do so. Pros and Cons There are many reasons that fingerprint scanner systems are used so vastly among corporations and agencies alike. They go by the who are you security system measurement which has many advantages. Physical attributes such as the fingerprint are difficult much more difficult to fake than identity cards are. Passwords can be guessed or brute forced, but a fingerprint can never be guessed or subverted this way. They also cannot be misplaced, as is the chief security risk of using cards and badges for authentication. Finally, fingerprints are a physical part of a human being, so they cannot be forgotten like one might forget his or her password (Do You Know). These pros make fingerprint scanners a formidable ally in physical security but they do have some short comings. As discussed previously, optical scanners pose a significant security risk because replica prints have been shown to defeat them. Capacitive scanners can also be fooled by a mold of a finger (Beat a Fingerprint). The main issue with fingerprint scanners has been the fact that fingerprints are not replaceable. Once someone s fingerprint is stolen, they are out of luck for the rest of their life (How Fingerprint). Even with the cons presented, fingerprint scanners are an ever increasing means of biometric identification. In the future they will most likely be part of ATM systems, door locks, and part of your checkout counter at the grocery store. Conclusion The fingerprint scanner is a piece of imaging technology that has served to protect against and prevent physical security breaches. Historically the fingerprint began being used as a means of by law enforcement to identify criminals, but now thanks to imaging technology, its use has expanded to other areas. Although, short comings have been identified in these complex systems, most corporations have begun combining fingerprint scanners with other forms of authentication to increase security. Such as, a personal identification number (PIN) to be used in association with the fingerprint scanner. The two-way authentication scheme is implemented in most major production lines thanks to the work of scientists that have set out to test fingerprint scanner security. The development of more complex methods of biometric analysis in conjunction with fingerprint image scanning technology will enable the development of an even stronger security device. 6 of 7

7 Bibliography Blass, Evan. Play-Doh Fingers Can Fool 90% of Scanners. December 11, Beal, Vangie. Do You Know -- Fingerprint Scanners. November 18, int.asp Harris, Tom. How Fingerprint Scanners Work Jayashree, Konda. Handbook of Fingerprint Recognition Untitled. Beat a Fingerprint Lock With a Photocopied Thumb. Sep 21, Untitled. Doubt Cast on Fingerprint Security. May 17, of 7