February 22, Biometrics: Fingerprints Basic fingerprints, scanners, simple program by Michael Liggett

February 22, Overview Introduction to Biometrics: Fingerprints Often Used Definitions Different Fingerprint Scanners Analysis of Fingerprints Algorithms Simple Program Conclusion

February 22, Basics Used for authentication on keyboards, mice, smart cards, and cellular phones (“Biometric”) Advantages include: no need for password memorization, less passwords (if any) saves time even if the passwords are strong, fingerprints are unique, and scanners are usually small in size Disadvantages include: Unlike passwords, you can not change fingerprint easily, the print can change with age, dirt and oil make for a non-perfect print, false fingerprints can be created that can allow attackers to attack systems Despite the advantages, I believe the disadvantages of biometrics can be outweighed by using more smart cards, encryption and less passwords.

February 22, Often Used Definitions  Ridge – tips of the fingerprint  Valley – concave part of a fingerprint between ridges  Bifurcation – a ridge that divides into two ridges  Minutiae – the features of a fingerprint (ex. bifurcations)  Template – mathematical formulas for fingerprints  False Accept Rate (FAR) – accepts a non-match  False Reject Rate (FRR) – rejects a match

February 22, Different Fingerprint Scanners One estimate of fingerprint scanners is 59.4% market share of all biometric security technology (“Prepared”). Typically, a scanner has a size of 500 pixels x 500 pixels and saved in grayscale format. (“Enhancing”) Optical - Light-emitted diodes known as a CCD (charge coupled device) create the electrical signal and stores the pixels. Light photons react making an electrical signal gives you the image with darker meaning ridges of the fingerprint. It will take another scan if the image is poor (lighting) and will adjust the exposure time. The sharpness of the image (also called the definition) will check for a good print by comparing horizontal and vertical lines and then saves the file. (“Fingerprint”)

February 22, Different Fingerprint Scanners… Capacitance – In this type of scanner, electrical current is used to store the fingerprint. Each cell of a semiconductor chip has three conductor plates (one is the finger – 50um), an insulator layer and an amplifier. The conductors make a charge. The distance between the plates change the capacitance (ridge creates > capacity). (“Fingerprint”) + semiconductors are usually smaller scanner than optical - must use a grounding grid because of electrostatic discharge allowing for > 15kV

February 22, Different Fingerprint Scanners… Ultrasound Refraction – Sends short acoustic signals and receives the echo sound. +Dirt and oil is not a factor for capturing the image - Larger than others and more $ Temperature Differential – Current is created on pyro- electric material. The touch of the ridges make different temperature differential from the valleys. Piezoelectric Effect – Non-conducting dielectric material creates a variable current due to pressure. (“Fingerprint”) - not as sensitive

February 22, Analysis There are several varieties of fingerprints that can be placed into different categories based on the ridges. Galton-Henry classification claim that 95% of the prints are arch, tented arch, right loop, left loop, and whorl. (“Towards”) Although identical twins appear the same in appearance, the fingerprints are different.

February 22, Fingerprint Algorithms Much like there is no one cryptographic algorithm, there are many different algorithms to identify a match. Some are much better than others. There are algorithm challenges to improve the use of Fingerprint Scanners. An example is FVC2002 (Fingerprint Verification Competition) (Biometric). Several considerations: Horizontal Positioning Vertical Positioning Rotation Other consideration is relative measures of the print.

February 22, Simple Fingerprint Program The end of the presentation will show a quick program I created to demonstrate some of the difficulties in creating an algorithm. The program includes: –Console program –A 10 X 10 matrix to represent a scanner –A fingerprint template to be compared to another –Bifurcations are points to identify uniqueness of the fingerprint

February 22, Possible Bifurcations (ridges)

February 22, Program continued… The program does not check for shift in horizontal, vertical, or rotation. Although primitive, the algorithm template can relatively match two prints and giving a basic idea of how one could create an fingerprint algorithm.

February 22, Program Images

February 22, Copyright © 2005 Neurotechnologija, Ltd.

February 22, Thoughts Benchmarking (Testing) – see how the device will work given the same templates and use thousands of prints in the same database Having a person’s fingerprint is having a person’s identification. Therefore, it is probably not wise to have more than one biometric security method. (ex. Facial, Iris or Hand Scan). Instead, a password or other methods can be used. An identification card (a token), smart cards, and/or ID number can help to prove real identity. (Fingerprint)

February 22, References “Biometric systems based on capacitive sensing technology.” TechNews, May “ D=248” “Economist: Prepare to be scanned.” Volume 369, Issue December 6, Academic Search Premier. Harris, Tom. “How Fingerprint Scanners Work.” “

February 22, References Rathy, Connell, Bolle. “Enhancing Securing and Privacy in Biometrics- Based Authentication Systems.” IBM Systems Journal, Volume 40, Issue 3, Ross, Arun and Jain, Anil. “Biometric Sensor Interoperability: A Case Study In Fingerprints.” Proc. Of Int. ECCV Workshop on Biometric Authentication (BioAW), LNCS,Volume 3087, pp May “VeriFinger 4.2: Screen Image.” Neurotechnologija, Ltd, “