Retinal Biometric Security

University of Maryland University College

Abstract

Retinal biometric security is a newer technology that is becoming increasingly popular, and with its advances in technology and increase in product suppliers, it’s undeniable that this is a growing methodology with surefire longevity. This method of biometric security is based on a retinal scan that involves the use of a low-intensity coherent light source projected onto the retina to illuminate the blood vessels, which are photographed and analyzed.
Due to the intricacies, a retina scan cannot be replicated, as it is impossible to forge a human retina. Because of this fact, a retinal scan has an error rate of 1 in 10 million; compared to fingerprint identification error rates sometimes as high as 1 in 500 (Biometric Newsportal, n.d.). In all its greatness, as with any technology, it comes with both advantages and disadvantages throughout the various phases of implementation. With the pros vastly outweighing the cons, retinal biometrics has still created its own namespace and presence in the world of technology.
With current retinal biometric applications and technologies being implemented in the financial, government, medical, and mobile sectors, it’s safe to bet that there is a great future laying ahead for this area of biometrics. Although there maybe anticipated competition, retinal scanning is currently leading the pack of biometrics methodologies and the trends prove that this will remain the case for many years to come.

Retinal Biometric Security

Biometrics
The word “biometrics” comes from the Greek language and is derived from the words bio (life) and metric (to measure). Biometrics, the measurements of life characteristics, refers to technologies used to measure and analyze personal characteristics, both physiological and behavioral. These characteristics include fingerprints, facial recognition, voice patterns, hand geometry measurements, iris code, retinal template, keystroke patterns, signature recognition, and DNA. These biometrics identify human characteristics and verify identity, they are tightly connected to an individual and cannot be forgotten, shared, stolen or easily hacked. Since biometrics can better solve the problems of access control, fraud and theft, more and more organizations are considering biometrics a solution to their security problems (Spinella, 2013).

What is Retinal Biometrics?
Retinography/Retinal Biometrics is a sophisticated means for identifying people by the pattern of blood vessels on the retina (the innermost coat of the back part of the eye). It requires the use of a special scanner about the size of a shoebox that can map the unique pattern of blood vessels on the retina. The pattern is so complex that even identical twins do not have the same blood vessel configuration. The overall retinal scanning process may be broken down into three sub-processes:

1. Image/signal acquisition and processing: this sub-process involves capturing an image of the retina and converting it to a digital format 2. Matching: a computer system is used to verify and identify the user 3. Representation: the unique features of the retina are presented as a template
A Deeper “Look”
The retina consists of multiple layers of sensory tissue and millions of photoreceptors whose function is to transform light rays into electrical impulses. These impulses subsequently travel to the brain via the optic nerve, where they are converted to images. Two distinct types of photoreceptors exist within the retina: the rods and the cones. While the cones (of which each eye contains approximately 6 million) help us to see different colors, the rods (which number 125 million per eye) facilitate night and peripheral vision. It is the blood vessel pattern in the retina that forms the foundation for retinal recognition as a science and technology (Das, 2013).

Side view of the eye within the retina Front view of the eye showing blood vessel pattern

Because of its position within the eye, the retina is not exposed to the external environment and is therefore a very stable biometric. The front view of the eye shows the blood vessel pattern within the retina. The red lines represent the actual blood vessels; the yellow section indicates the position of the optic disc (the place where the optic nerve joins the retina). It is from here that information is transmitted to and received from the brain. The dash circle in the diagram indicates the area that is typically captured by a retinal scanning device. It contains a unique pattern of blood vessels.
There are two famous studies that have confirmed the uniqueness of the blood vessel pattern found in the retina. The first was published by Dr. Carleton Simon and Dr. Isodore Goldstein in 1935, and describes how every retina contains a unique blood vessel pattern. In a later paper, they even suggest using photographs of these patterns as a means of identification. The second study was conducted in the 1950s by Dr. Paul Tower. He discovered that - even among identical twins - the blood vessel patterns of the retina are unique and different (Das, 2013).

Accuracy
Biometric accuracy is the ratio of the frequency as compared to the whole population of test data. The smaller the error rate, the more unique the biometrics would be. Every biometric technique has a different method of assigning a "score" to the biometric match; a "threshold value" is defined which determines when a match is declared (Retinal Scanners, n.d.). Scores above the threshold value are designated as a "Hit" and scores below the threshold are designated as "No-Hit”. In general, as the value of the accuracy increases the inherent accuracy of the biometric increases (Ruggles, 1996).

Biometric | Accuracy | Retinal Scan | 1:10,000,000+ | Iris Scan | 1:131,000 | Fingerprints | 1:500 | Hand Geometry | 1:500 (against a very small background database) | Signature Dynamics | 1:50 | Voice Dynamics | 1:50 | Facial Recognition | no data | Vascular Patterns | no data |
Table 1: Biometric Accuracy

Of all biometric techniques listed in Table 1, only Signature Dynamics and Voice Dynamics rely on behavioral characteristics rather than physical characteristics. Biometrics that are considered to be accurate enough to fulfill the requirements of a large-scale (one million plus individuals) Biometric-Based Identification System are: Retinal Scan/Vascular Pattern, Iris Scan, and Fingerprints (Ruggles, 1996). The accuracy values in the table above were generated by use of a single instance of the biometric (Ruggles, 1996).

Pros and Cons

Retina-Based Implementations | Advantages | Disadvantages | Overall Life Cycle | Combined phases, enrollment and authentication can yield very low false positives and is therefore desirable for high- security applications, such as military or banking applications. | Non-revocability of lost or stolen biometric data, operational efficiency, and user resistance are primary disadvantages. | Enrollment Phase(Scanning initiates the creation of a retina-based biometric template that is a product of both a user’s retina- based data and storage algorithms) | A retina-based data template is highly manipulative after a retina is scanned. A scan can be protected using a variety of storage schemes, such as a “fuzzy vault” scheme (e.g., Juels & Sudan, n.d.). Because retinas are internal organs deep within the eye, retina scans and retina-based templates are more resistant to spoofing, intentional or unintentional modifications, aging modifications, and temporal modifications (Meenakshi & Padmavathi, 2009). Retina scans generally require less storage than fingerprint scans, generate more “genuine points” from the retina’s vascular tree than an iris scan, and can be utilized with other techniques to produce highly-secure encryption schemes (Meenakshi & Padmavathi, 2010). A retina scan produces a biometric template with fewer distortions or contaminations because it does not require user contact with scanner materials, does not contaminate from background noises or changes caused by illness, and is even slow to change after death (Meenakshi & Padmavathi, 2010). | Non-revocability is a primary disadvantage. Non-revocability means that biometric data cannot be recovered and changed, unlike a password, a token, or other revocable item. Non-revocability is a critical issue for retina-based, iris-based, and other biometric system evaluations, and also for user acceptance. Non-revocability increases concerns about user privacy and security, and is considered a primary vulnerability of biometric systems, including retina-based systems (Nandakumar, 2008).Retina scanning operations can be impractical and expensive for high- traffic, low security authentication needs. Operations still require both user and operator experience for the enrollment and scanning process to go smoothly, Retina scanning technologies may also feel less comfortable and more invasive to use, since an infrared light is penetrating the eye to illuminate the retina’s vascular blood vessels for image capture. Furthermore, comfortability and invasiveness factors may further compound a broader and more general resistance from users already present with other biometric scanners, e.g., fingerprint, voice, facial, etc. (Johnson, 2012). | Authentication Phase | Enables multi-factor authentication via stored retina-based templates, combining the “something I have” factor, the “something I am”, and the “something I know” factor (e.g., passwords) to create hybrid templates. This eliminates key distribution problems and mitigates spoofing, “replay”, or other template attacks (Meenakshi & Padmavathi, 2010).Retina-based multi-factor authentication enables biometric systems to address non-revocability issues by including something revocable within biometric templates (e.g., passwords, keys, etc.) and using strong encryption to prevent the source “genuine points” from being deciphered (Nandakumar, 2008). | Elaborate schemes are required to mitigate non-revocability, yet retina- based identify management systems require diversity, revocability, security, and performance (Jain, Nandakumar & Nagar, 2009). Diversity ensures that prohibiting biometric template comparisons across databases protects a user’s privacy. Revocability ensures that a compromised security template can be recalled and a new security template can be issued. Security ensures there is computational difficulty in deriving biometric data. Performance ensures that template protection doesn’t impair user recognition. Retina-based security templates must therefore apply additional mechanisms beyond retina data to achieve revocable security templates (Meenakshi & Padmavathi, 2010). |

Current Applications & Technology
Just like any other physical biometrics, such as fingerprint or facial recognition, Retinal Biometrics can be used alternatively in the identification of a person. Retina scans are already in use in the Pentagon, as well as government and corporate organizations where authorization and identification are required before entry into an area. New concerns about security from terrorism and bank and credit card fraud have caused many organizations to think seriously of using retina scans in combination with other biometric means to identify people at airports and ATM machines.
Some states require that truck and bus drivers be mapped by retinography. This information is used by state agencies to prevent bad drivers from holding licenses in several states to hide their driving records. A proposed—and more controversial—use of retina scans is to develop a worker registry, where everyone is scanned to ensure legal citizenship of the United States, and thus eligible for employment.
In addition to the aforementioned uses of retinal biometrics, the following are other areas where it’s also being implemented across various sectors:

* Computer logins * Wireless device authentication * Ticketless travel * Access Security * Hospital tracking * Passports * Automobile ignition and unlocking * National border control

As the industry grows, so does the supplier of technology. Listed below are the current retinal biometrics technology providers (Biometric Scanners, 2013):

* * Cross Match Technologies * Smart Sensors * SecuriMetrics * Fulcrum Biometrics * Smartmatic * MorphoTrak * Iris ID * IriTech * Neurotechnology * SRI Sarnoff

Future of Retinal Biometrics
Retina-based identification and authentication applications have several advantages as previously discussed and therefore likely to continue as viable options for the foreseeable future, especially for high security applications. Furthermore, retina scanners are likely to become more efficient, easy to use, and less expensive to acquire, operate, and maintain just as other IT products have. This trend is an enabler for more organizations to consider retina-based security solutions for their needs. The next major step for retina-based identification is for this process to be achieved in a great number in a fraction of the time. Organizations are developing technology that would scan a large number of retinas at one time from a distance of several feet (Olzak, 2010). With this kind of technology, individuals that are scanned would not be required to stop, instead they can remain in motion and be scanned simultaneously. Organizations like domestic airports and government entities are looking to be the first to implement such advancements. In the food industry, a company called Next Generation is developing vending machines that will scan a person’s retina to identify, authorize, and charge the individual for their purchase. This alludes to the notion that credit card information, can and will be linked to a person’s retina scans. Although this technology has not been introduced to the states, it is in the works and something to look forward to in the near future (Reso, 2010).
It doesn’t stop there! Advancements in technology have challenged the initial intent of retina scans by reversing its functionality. In a nutshell, the retina will be scanned and if the person is looking at a source of information, that information can be super imposed into their retina (Cooper, 2004). So the way we game, look at computer content, or watch television will be altered into a more personal experience.
Current security advantages, however, may be diminishing. For example, in the near future DNA-based biometrics will surpass retina scans in using far more “genuine points”. DNA-based identification and authentication may also encounter fewer disadvantages currently found with retina-based systems because a DNA profile may be captured more easily than a retina scan, such as via a cheek swab.
References

Biometric Newsportal. Retrieved on March 9, 2013 from http://www.biometricnewsportal.com/retina_biometrics.asp
Biometric Scanners & Recognition. (2013) Retrieved from http://findbiometrics.com/solutions/iris-scanners-recognition/
Cooper, B. (2004). Retinal Scanning – Reversed! Retrieved on April 7, 2013 from http://www.futurist.com/articles-archive/retinal-scanning-reversed/
Das, R. (2013). Retinal recognition - Biometric technology in practice. Biometricnews.net. Retrieved from http://www.biometricnews.net/Publications/Biometrics_Article_Retinal_Recognition.pdf Jain, A. K., Nandakumar, K., & Nagar, A. (2009). Biometric template security. EURASIP Journal On Advances In Signal Processing (Internet), 1. doi:10.1155/2008/579416
Johnson, S. (2012). Skeptics scoff, privacy advocates protest as biometric IDs advance. San Jose Mercury News (CA).
Juels, A., & Sudan, M. (n.d.). A fuzzy vault scheme. Designs Codes And Cryptography, 38(2), 237-257.
Meenakshi, V. S., & Padmavathi, G. G. (2009). Security analysis of password hardened multimodal biometric fuzzy vault. World Academy Of Science, Engineering & Technology, 56 312-320.
Meenakshi, V. S., & Padmavathi, G. G. (2010). Securing revocable iris and retinal templates using combined user and soft biometric based password hardened multimodal fuzzy vault. International Journal Of Computer Science Issues (IJCSI), 7(5), 159-167.
Nandakumar, K. (2008). Multibiometric Systems: Fusion Strategies and Template Security (Doctoral Thesis). Retrieved from http://biometrics.cse.msu.edu/theses.html
Nanvati, S. (2002), Biometrics: Identity verification in a networked world. New York: Wiley and Sons, Inc, page 106.
Olzak, T. (2010). The future of iris scanning. Retrieved on April 7, 2013 from http://www.techrepublic.com/blog/security/the-future-of-iris-scanning/3978
PBworks. (2006). Advantages and Disadvantages of technologies. Retrieved on March 9, 2013 from http://biometrics.pbworks.com/w/page/14811349/Advantages%20and%20disadvantages%20of%20technologies
Reso, P. (2010). Future vending machines will link thumbprints, retina scans, to credit card. Retrieved on April 7, 2013 from http://www.nydailynews.com/news/money/future-vending-machines-link-thumbprints-retina-scans-credit-card-article-1.204234
Retinal Scanner. Retrieved on April 5, 2013 from http://techbiometric.com/articles/retinal-scanner-biometrics/
Ruggles, T. (1996). Comparison of Biometric Techniques. Retrieved on April 5, 2013 from http://www.bioconsulting.com/bio.htm
Spinella, E. (2013). Biometric Scanning Technologies: Finger, Facial and Retinal Scanning. Sans.org. Retrieved from
http://www.sans.org/reading_room/whitepapers/authentication/biometric-scanning-technologies-finger-facial-retinal-scanning_1177