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Posted by:
Deepak
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BIOMETRICS SYSTEMS-2
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BIOMETRICS SYSTEMS-2
How Do Biometric Systems Determine Matches ?
Biometric decision-making is frequently misunderstood. For the vast majority of technologies and systems, there is no such thing as a 100% match, though systems can provide a very high degree of certainty. The biometric decision-making process is comprised of various components, as indicated below.
Matching - The comparison of biometric templates to determine their degree of similarity or correlation. A match attempt results in a score that, in most systems, is compared against a threshold. If the score exceeds the threshold, the result is a match; if the score falls below the threshold, the result is a non-match.
Biometric comparisons take place when proprietary algorithms process biometric templates. These algorithms manipulate the data contained in the template in order to make valid comparisons, accounting for variations in placement, background noise,etc. Without the vendor algorithm, tere is no way to compare biometric templates – comparing the bits which comprise the templates does not indicate if they came from the same user. The bits must be processed by the vendor as a precondition of
comparison.
The matching process involves the comparison of the match template, created upon sample submission, with the reference template(s) already on file. In 1:1 verification systems, there is generally a single match template matched against a reference template. In 1:N identification systems, the single match template can be matched against dozens, thousands, even millions of reference templates.
In most systems, reference and match templates should never be identical. An identical match is an indicator that some sort of fraud is taking place, such as the resubmission of an intercepted or otherwise compromised template.
Score – A number indicating the degree of similarity or correlation of a biometric match. Traditional verification methods –passwords, PINs, keys, and tokens - are binary, offering only a strict yes/no response. This is not the case with most biometric systems. Nearly all biometric systems are based on matching algorithms that generate a score subsequent to a match attempt. This score represents the degree of correlation between the match template and the reference template.There is no standard scale used for biometric scoring: for some vendors a scale of 1-100 might be used, others might use a scale of –1 to 1; some vendors may use a logarithmic scale and others a linear scale. Regardless of the scale employed, this verification score is compared to the system’s threshold to determine how successful a verification attempt has been.
Incidentally, many systems return a score during enrollment, referred to as an enrollment score or quality score. This score refers to how successful the extraction process was at finding distinctive features in the biometric sample. If the sample was rich in information, there will likely be a high enrollment score. This score is not used in the matching process, but might be used to determine whether a user can enroll successfully. A low quality score may indicate that the user cannot be reliable verified.
Threshold - A predefined number, often controlled by a biometric system administrator, which establishes the degree of correlation necessary for a comparison to be deemed a match. If the score resulting from template comparison exceeds the threshold, the templates are a “match” (though the templates themselves are not identical).When a biometric system is set to low security, the threshold for a successful match is more forgiving than when a system is set to high security.
Decision – The result of the comparison between the score and the threshold. The decisions a biometric system can make include match, non-match, and inconclusive, although varying degrees of strong matches and non-matches are possible.Depending on the type of biometric system deployed, a match might grant access to resources, a non-match might limit access to resources, while inconclusive may prompt the user to provide another sample.
One of the most interesting facts about most biometric technologies is that unique biometric templates are generated every time a user interacts with a biometric system. As an example, two immediately successive placements of a finger on a biometric device generate entirely different templates. These templates, when processed by a vendor’s algorithm, are recognizable as being from the same person, but are not identical. In theory, a user could place the same finger on a biometric device for years and never generate an identical template.
Therefore, for most technologies, there is simply no such thing as a 100% match. This is not to imply that the systems are not secure – biometric systems may be able to verify identify with error rates of less than 1/100,000 or 1/1,000,000. However,claims of 100% accuracy are misleading and are not reflective of the technology’s basic operation.
Are Biometric Systems Difficult to Use?
Biometrics are much easier to use than one might expect. Here is a brief technology-by-technology summary of how one interacts with biometric systems.
Fingerprint - When prompted, the user gently places his or her finger on a postage-stamp sized optical or silicon surface. This surface, known as a platen, is built into a peripheral device, mouse, keyboard, or PCMCIA card. The user generally must hold the finger in place for 1-2 seconds, during which automated comparison and matching takes place. After a successful match, the user has access to programs, files, or resources. Typical verification time from “system ready” prompt: 2-3 seconds.
Facial recognition - User faces the camera, preferably positioned within 24 inches of the face. Generally, the system will locate one’s face very quickly and perform matches against the claimed identity. In some situations, the user may need to alter his facial aspect slightly to be verified. Typical verification time from “system ready” prompt: 3-4 seconds.
Voice recognition- User positions him or herself near the acquisition device (microphone, telephone). At the prompt, user either recites enrollment pass phrase or repeats pass phrase given by the system. Typical verification time from “system ready” prompt: 4-6 seconds.
Iris recognition- User positions him or herself near the acquisition device (peripheral or standalone camera). User centers eye on device so he or she can see the eye’s reflection. Depending on the device, the user is between 2-18 inches away. Capture and verification are nearly immediate. Typical verification time from “system ready” prompt: 3-5 seconds.
Retina-scan- User looks into a small opening on a desktop or wall-mounted device. User holds head very still, looking at a small green light located within the device. Typical verification time from “system ready” prompt: 10-12 seconds.
Hand geometry- User places hand, palm-down, on an 8 x 10 metal surface with five guidance pegs. Pegs ensure that fingers are placed properly, ensure correct hand position. Typical verification time from “system ready” prompt: 2-3 seconds.
Signature verification- User positions himself to sign on tablet (if applicable). When prompted, user signs name in tablet’s capture area. Typical verification time from “system ready” prompt: 4-6 seconds.
Keystroke biometrics- User types his or her password or pass phrase. Typical verification time from “system ready” prompt: 2-3 seconds.
System Block Diagram of Fingerprint Biometrics
The fingerprint sensor captures an image of the finger and relays it to the DSP. The DSP runs image enhancement, template extraction and identification and/or authentication algorithms to match the captured image against stored fingerprint templates.On a successful match, the DSP sends a signal across the RS232 standard to authorize access to the secured asset along with using some form of visual or audio signal to let the user and the system know that the user is verified. On a failed match,some form of visual or audio signal can be generated using the DSP to alert the users and the administrators.
Solutions for biometric products based on Texas Instruments DSPs provide developers the flexibility to design a wide range of products. By leveraging the DSP programmability, low power consumption and high processing performance developers can design highly accurate, differentiated products with customized features to meet changing market needs.
The Fingerprint Biometric System uses TI DSP technology, coupled with identification (1:n) and authenication (1:1) software and a fingerprint sensor. TI has partnered with a number of third parties to provide software that enables a variety of TI DSPs on a number of popular fingerprint sensors on the market today such as Authentec, FingerPrint Cards and Atmel. TI DSP solutions support biometric software from a number of vendors, including 123id, Bioscrypt and Fingerprint Cards among others.
The core subsystems include:
* DSP- Digital Signal Processor capable of running high speed mathematically intensive Authentication (1:n) and Verification 1:1)fingerprint matching algorithms
* Fingerprint Sensor- Biometric sensor capable of capturing distinguishing features of a fingerprint in digital format
* External Memory- stores executing code and data/parameters such as fingerprint templates
* RS232 Dual Channel/Receiver- Converts TIA/EIA-232-F inputs to 5V TTL/CMOS levels for interfacing across the RS232 standard
* Power Management - Converts the input power from the AC adaptor or battery to the correct regulated voltages for various functional blocks.
Benefits of Biometric Technology
For employers
Reduced costs – password maintenance
Reduced costs – no buddy punching
Increased security – no shared or compromised passwords
Increased security – deter and detect fraudulent account access
Increased security – no badge sharing in secure areas
Competitive advantage – familiarity with advanced technology
For employees
Convenience – no passwords to remember or reset
Convenience – faster login
Security – confidential files can be stored securely
Non-repudiation – biometrically transactions difficult to refute
For consumers
Convenience – no passwords to remember or reset
Security – personal files, including emails, can be secured
Security – online purchases safer when enabled by biometric
Privacy – ability to transact anonymously
For retailers (online and point-of-sale)
Reduced costs – biometric users less likely to commit fraud
Competitive advantage – first to offer secure transaction method
Security – account access much more secure than via password
For public sector usage
Reduced costs – strongest way to detect and deter benefits fraud
Increased trust – reduced entitlement abuse
* To learn more about the benefits of biometrics, read about biometric usage in the various Industries that IBG services.
* For a comparison of the strengths and weaknesses of biometric technology, read IBG s Biometric Technologies reports.
* To lean more about the benefits of biometrics in specific applications, read IBG s Industry and Applications reports.
BIOMETRICS SYSTEM-1
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