Fingerprint identification once was exclusively the domain of law enforcement and government agencies. Fingerprints could be used to identify criminals by matching their prints against a large national database. Governmental organizations with highly confidential premises and hefty budgets were attracted to biometric security options and could afford to implement them. Large, unwieldy and prohibitively expensive, the fingerprint sensor was not a feasible security option for typical consumer electronic devices sold at retail outlets. Since the turn of the millennium, however, the technology has made significant advances and is well on its way to becoming as widespread as wireless networks, MP3s and handheldsnone of which were widely recognized as recently as a decade ago.
Today, numerous models of desktop, notebook and Tablet PCs as well as peripheral products in the U.S. market are available with biometric security options at major retailers such as Circuit City and Best Buy. They come from top manufacturers such as Fujitsu Computer, Samsung, Motion Computing, Memory Experts and APC. In the gadget-friendly Asian market, biometrically enabled devices are even more popular. Cell phones on the NTT DoCoMo network in Japan and manufacturers like LG are equipping their phones with fingerprint sensors for security and convenient navigation.
When compared to common security methods, such as passwords, keys and PINs, fingerprints win on security and convenience, and come out on top as the only viable option for electronics security. It is more reliable than voice recognition, which can be rendered useless in a noisy cafe or even on a windy day in the park. And it is easier and far less expensive to use for these purposes than retina or iris scanning.
In past decades, fingerprint sensors had to be large enough to capture the entire print surface in order to be effective in identifying the print's owner. That is no longer the case. Sensor size has dropped from that of a silver dollar to less than that of a pencil point. Improved technology that can accurately identify a user with a partial fingerprint rendered the large sensors of the past unnecessary. Furthermore, the latest slide sensors are even smaller and more cost-effective. These new high resolution slide sensors provide a high degree of detail and capture a relatively large area of the finger by scanning as the user slides a finger across the sensor surface.
An example is AuthenTec's EntréPad family of slide sensors which use mixed signal analog technology for a sensor array configured in a matrix of individual receive channels. The sensor is organized in a 192 x 16 element array with separate individual receive channels that can be quickly scanned. During image collection, the 192 wide columns are powered up and the signals from each of the 16 pixels are sampled, digitized and returned to the host processor over the selected interface sequentially. This technique allows for a smaller sized sensor.
Figure 1: AuthenTec's EntréPad AES2510 sensor is optimized for wireless applications using either Synchronous Serial or 8-bit parallel Interfaces. The AES2510 allows for convenient operation with either a Crystal, a low cost resonator, or with externally supplied clock input. (Source: AuthenTec)
The decrease in the size of the sensors was accompanied by a substantial drop in price. When the original modular sensor devices were replaced with silicon integrated sensor devices, the biggest factor influencing the cost of the sensor became the price of the silicon itself. While some of the original fingerprint sensors cost nearly one hundred dollars, they now go for less than $5, and the price will drop further. This is a major attraction for product designers looking for additional features to increase the product's price point without incurring much more of an expense in manufacturing costs.
Small silicon die size drives sensor costs down, but equally important to the product designer is the total cost of designing this feature into their solution. Slide sensors can provide multiple data interface options, including USB, Synchronous Serial and 8-bit parallel. These types of integrated product features, as well as multiple clock alternatives, allow the designer to integrate with a minimum of extra components needed on the printed circuit board.
The most critical factor contributing to today's record level of adoption is the improved performance and reliability of today's fingerprint sensors. Although some sensors still use traditional surface-based solutions, today's most advanced slide sensor technology can read the fingerprint from below the skin's surface layer, meaning that it will perform reliably even in instances of worn, injured or dry fingers. AuthenTec's TruePrint Technology, for example, uses a patented radio frequency (RF) imaging technique that employs a modulated field conducted into the live layer of the finger. This field is carried by a layer of saline that is directly adjacent to the live emerging finger ridges below the surface of outer dead skin. The saline is a natural by-product of the live finger ridge cells as they go through their life cycle. This sub-surface layer is highly conductive and the resultant field then assumes the shape of the live finger ridges, and propagates to the array. The sensor controls multiple parameters of field modulation to optimize the RF imaging process as the finger slides across the sensor. This process is called Dynamic Optimization and is one of the primary reasons that these sensors can image everybody under virtually any conditions. The sensor collects an image of the shape of the live layer of the skin beneath the finger's surface. Another added bonus is that the fingerprint cannot be reproduced under this methodand used to fool the sensor.
In addition, the slide sensor can include other security features when used in conjunction with software. For example, AuthenTec's combined silicon and software solution features a robust matching algorithm that enables highly secure user matching. Users register on a device or enroll by creating a template which is stored in persistent memory. When a user wants access to the device, he swipes a finger and a mathematical formulation generated from the live scan is matched against the pre-stored template.
Highly robust security architecture protects interfaces associated with each hardware and software component. Template encryption, code signing, and run time authentication are some of the many built-in security techniques that all combine to make this architecture highly resistant to spoofing. AuthenTec provides drivers that are composed of library components such as the matcher and control code as well as platform specific code. The drivers are already ported to most of the popular operating systems shipping in volume commercial products today, including Windows, WinCE, Symbian, Linux and Qualcomm REX / BREW, as well as lower level operating systems, such as uITRON and Nucleus.
The latest slide sensor technology facilitates the production of enduring sensors that have thicker protective surface coatings, higher scratch and abrasion resistance, and exceptional resistance to chemical and environmental hazards. It allows for low cost, small area sensors to deliver performance exceeding that of larger, more expensive sensors using other technologies. These innovations have helped drive the rapid adoption rates in the worldwide consumer market.
Take the modern cell phone for example. The cell phone is evolving into a "smarter" phone with advanced wireless capabilities and has brought the importance of securing these devices to the top of the manufacturer's priority list. Contact lists, personal data files and imagery from high resolution cameras all need what is called Client Side Protection. Connection to high speed data services adds more personal information to the phone, and now with access to company networks, advancements on the security front is critical. The need for too many passwords and challenging user interfaces has opened the door to "simply swipe your finger" security, a convenient alternative which is growing in popularity among users.
Another application for these sensors comes from the world of finance. M-payment, or mobile banking, is now emerging in Japan and Korea. NTT DoCoMo subscribers are currently able to make purchases with their cell phones and slide sensors protect access to this feature. In Korea, the AuthenTec EntréPad slide sensor is protecting access to users' online accounts for mobile banking. Monetary transactions are executed by the phone and the phone migrates to an e-wallet capability, increasing the importance of convenience-based security.
Low Battery Consumption
Highly utilized features in embedded platforms present special considerations in processor loading and power consumption. Navigation is a cell phone feature that can be utilized constantly, and as such, it is critical that it can be executed with minimal processor loading and low battery consumption. Slide sensors are capable of handling this challenge, as well. The AuthenTec EntréPad, for example, is designed with an on-board navigation engine as well as on-chip DMA support to minimize the host processor burden. Full navigation is performed with a resultant processor loading of less then 5%. Also, during navigation and imaging, the slide sensor employs power cycling techniques not only to limit power drain but also as an ESD countermeasure technique. Full motion navigation results in a power drain of less than 2mA. This combination of low processor burden and low power drain make the slide sensor, such as the EntréPad (with no companion chips needed), a compatible member of modern embedded platforms.
The master-mode SPI interface and navigation-packet timing technology introduced by such sensors eliminates a majority of host-processor intervention for image capture and navigation, and at less cost than competitive products, because it requires no companion-chip. The sensor requires only a half-second for authentication, whereas older technology interrupts other time critical processes as it communicates with the host.
There are a variety of tools that can help an OEM Design Team integrate the slide sensor. In the PC market, AuthenTec and other manufacturers offer full WHQL drivers for all PC based applications, and software will be shipping native in the next Microsoft release of Longhorn. In the embedded market, fully tested slide sensor drivers now exist for every popular OS and computer platform being used in the wireless market today, including Symbian, Rex / BREW, WinCE, Linux, and even lower level OS such as uITRON, Nucleus and AMX. Fingerprint sensor providers are able to offer software modules augmented with platform specific code and presenting a standard API for easy application development. Embedded System Design Kits, Integrators Guides and Programmers Reference Guides provide helpful references. Partner networks support development of a multitude of popular biometric applications. On the hardware integration front, Reference Design Kits are available to assist the designer.
A Bright Future
Fingerprint sensor technology has made dramatic innovations and the results are emerging on the consumer market. AuthenTec has more than 3 million sensors in use today, less than one year after reaching the one million mark. Most of that growth has been in the PC/peripheral and wireless markets. These numbers indicate that consumers are warming quickly to the idea of biometric options to secure their electronic devices.
Japan's NTT DoCoMo network may provide the most convincing substantiation of the increasing popularity of biometrically enabled wireless devices. In total, Japan has 78 million cell phone subscribers and AuthenTec's biometrically-enabled cell phones have a 4% market shareimpressive for a new, emerging technology. This market share is so impressive that Korean provider LG Telecom took notice and introduced its first biometrically enabled phone to that market in September.
Furthermore, the demand by cell phone users for increased services and features will continue to influence manufacturers to seek out new additions that can increase the value of the phoneswithout resulting in a hefty increase in manufacturing costs.
The migration of cell phone based biometrics is following the roll out of advanced carrier services. NTT DoCoMo's roll out of their 3G network capability years ago and strategic vision of the phone migrating to an e-Wallet capability made it the natural choice to incorporate convenience based security. In Korea, where data services are extremely popular, fingerprint based security has also become a mainstream feature. High speed data services and advanced features result in a higher value attached to convenience based security, and OEMs are viewing the fingerprint sensor feature as a means of differentiating their phones on the marketplace. In China, both the popularity of Smart Phones and the roll out of their 3G infrastructure, make it the logical next beachhead for cell phone based biometrics in 2005. Although we are already seeing PC based biometrics surface in Europe and the U.S. today, wireless platforms will likely follow the roll out of advanced carrier applications as they make their way around the globe in the latter half of 2005.
About the Author
Art Stewart is the Vice President of Business Development for AuthenTec, where he brings 25 years of experience in the semiconductor and communication industries. Mr. Stewart joined AuthenTec in 2001 and spearheaded the company's leadership in the worldwide wireless communication markets. Prior to joining AuthenTec, Mr. Stewart served in various senior level engineering positions associated with communication system design and development. His broad range of experience includes running a 200-person engineering department at Harris Corporation's Government Systems Division and co-founding a high tech start up company that provided personal security services for college campuses using tracking and location technology. Mr. Stewart holds three patents in communication systems design and semiconductor technology. He received a BSEE from the University of Delaware and an MBA from Florida Institute of Technology.