WO2006036086A2

WO2006036086A2 - Biometric identification method

Info

Publication number: WO2006036086A2
Application number: PCT/RU2005/000473
Authority: WO
Inventors: Panos Razis; Hans Rykaczewski; Ivan Sergeevich Vasiliev; Vitaly Sergeevich Kaftanov; Viktor Albertovich Minkin; Alexandr Iliich Shtam
Original assignee: Oao 'tsnii 'elektron'
Priority date: 2004-09-22
Filing date: 2005-09-19
Publication date: 2006-04-06
Also published as: RU2286599C2; WO2006036086A3; RU2004128951A

Abstract

The invention relates to biometry and can be used for access control and passport systems. The inventive method consists in reading (inputting) information about the user's biometric parameter, in comparing the thus obtainable information with a sample and in protecting against a counterfeit biometric parameter. In order to increase the reliability of a biometric identification system by reducing a number of errors while detecting counterfeit biometric carriers, the protection against the counterfeit biometric parameter is carried out by measuring mechanical movements of a given biometric parameter, by determining movement parameters peculiar thereto and by rejecting the inputted biometric parameter as counterfeit when said parameter deviates from a specified standard. The biometric parameter can be embodied in the form of a finger print whose mechanical movement is measured according to the time dependency of the contact surface area thereof, wherein said contact surface area is determined by using the parameters of the biometric signal carrier frequency distribution, for example the width of a root-mean-square deviation.

Description

METHOD FOR BIOMETRIC IDENTIFICATION

Technical field

The invention relates to the field of biometrics and can be used to protect against fake biometric parameters in access control systems and passport systems.

State of the art

The global development of biometric systems creates natural prerequisites for the development of systems and methods for falsifying biometric parameters, as well as the development of systems and methods for protecting against tampering with biometric identification. Conventionally, all methods of protection against fake or falsified biometric parameters can be divided into static and dynamic. Static methods of protection should include an additionally determined instantaneous value of a certain physical quantity, which should be inherent in the real biometric parameter and absent in the falsified one. An example of such protection can be the determination of the electrical resistance of the skin of a finger or hand for fingerprint sensors and systems using a special electrode system (RU 2218084, MKI A61B5 / 117, publ. 10.12.2003, US 6175641, MKI A61 B5 / 117B, publ. 16.01. 2001), as well as for identification by palm shape (US 6181808, MKI G06K9 / 00, op.30.01.2001). The known principle of obtaining a fingerprint image in the light passing through the finger (RU p.2031625, MKI A61 B5 / 117, op.27.03.95, US p.6668071, MKI G06K9 / 00, op.23.12.2003, RU p.2195020 , MKI G06K5 / 00, 19/00, G07F7 / 10, op.20.12.2002).

Another example of static additional protection is the measurement of the temperature of an object and other physiological parameters inherent in humans, which is used both in contact biometric identification systems, for example fingerprint systems (US 5719950, MKI G06K9 / 00, publ. 02.17.1998), and in non-contact systems, for example recognition systems for the face or retina. An additionally measured physical quantity makes it possible in some cases to reject fake biometric media, however, if this physical quantity is known, then it is possible to use it in falsified biometric parameter. To falsify, for example, the electrical resistance of the skin, it is sufficient to produce a fake fingerprint of electrically conductive silicone having an electrical resistance similar to that of the skin of a finger. To falsify thermal protection, it is sufficient to fabricate a fake carrier from a material with good thermal conductivity, then it is practically impossible to detect fake by the static method. In addition, the introduction of the measurement of an additional parameter requires the creation of additional hardware, for example, an electrode system on a fingerprint sensor for measuring the electrical resistance of the skin or a temperature sensor for measuring body temperature. This leads to an increase in the cost and complexity of the biometric identification system and reduces the reliability.

Thus, static methods of protection against fake biometric media do not provide real identification of fake media, because based on the measurement of additional static parameters that only partially reflect the properties of living objects.

Another possible method of static protection during biometric identification is a detailed analysis of the form of the input biometric parameter. Indeed, a fake is usually made less qualitatively than the original, which contains a huge number of small parts that are not transmitted during the manufacture of the fake. For example, for a fingerprint, it can be pores on the skin (poroscopy) or the shape of the edge of the papillary line (ejoscopy), which differ significantly on the original and the fake. However, for a detailed analysis of the shape of the biometric parameter, it is necessary, first of all, to have a high resolution scanner. For reliable identification by specific points of the fingerprint, it is enough to have a scanner resolution of 500 dpi (with an area of ~ 1.5 cm ² ), and for analyzing the shape it is desirable to have a resolution of more than 1500 dpi. Such a high resolution significantly complicates the operation of the system in real time, increases the cost of the system and, ultimately, does not give a guarantee of protection, because it is possible to produce a fake biometric carrier taking into account the increased resolution.

Known dynamic methods of protection against fakes are based on the analysis of changes in time of the main or additional biometric parameter. The most famous biometric parameter characterizing a real person is his pulse and pulse waves, caused by the contraction of the heart muscle.

The known method, a pulse wave registration device and a biometric identification system that allows to identify fake carriers of fingerprint information due to the effect of the volume pulse observed at the fingertips, i.e. synchronous pulse waves recorded at various points and areas of the same object. The specified method includes reading information about a user's biometric parameter - registering a pulse wave by illumination of a blood-bearing tissue, converting the light flux caused by scattering on a blood-bearing tissue into an electrical signal using an optoelectronic converter, processing the resulting pulse wave using several photosensitive regions located nearby places of a blood-bearing tissue, comparison of the received information with a sample and protection against fake biometrics th parameter using information about the volume pulse (RU 2199943, MKI A61 B5 / 02, publ.

03/10/2001).

The method allows to successfully identify fake carriers of a fingerprint image in the presence of a normal peripheral pulse in the fingertips. However, it is known that in some diseases the peripheral pulse in a person may be practically absent, there is also a significant decrease in the peripheral pulse associated with a decrease in the size of microcapillaries, for example, when the body is cooled, or when the person is nervous. This property significantly limits the use of this method to detect fake fingerprint media. In addition, this method of protection is applicable only to systems operating in the light passing through the object, and these systems form an insignificant part of the biometric market.

SUMMARY OF THE INVENTION

The proposed method solves the problem of increasing the reliability of the biometric identification system by reducing errors in identifying fake biometric media.

This is achieved by the fact that in the known method of biometric identification, including reading (entering) information about the biometric parameter of the user, comparing the received information with the sample and protection from a fake biometric parameter, protection against a fake biometric parameter is carried out by measuring the mechanical movement (movement) of a given biometric parameter, the motion parameters inherent in the biometric parameter are detected and rejected biometric parameter is rejected when the specified parameter deviates from the established norm.

In another embodiment of the method, a fingerprint is used as a biometric parameter, and the mechanical movement of the fingerprint is measured by the time dependence of the area of the contact surface of the fingerprint.

The difference is also that the contact surface area of the fingerprint is determined using the parameters of the distribution density of the signal of the biometric carrier, for example, the width of the standard deviation.

In a further embodiment of the method, the mechanical movement of the biometric parameter is measured using the time dependence of the integral value, for example, the center of gravity of the given biometric parameter.

It is known that the pulse wave, moving inside the human blood vessels, changes the blood supply, and hence the transparency of the blood vessels inside the human body (RU 2199943, MKI A61 B5 / 02, publ. 10.03.2001). It is also known that in accordance with Newton’s third law for a closed system, the law of conservation of momentum must be satisfied, i.e. internal movement should cause external movement. Of course, the human body is a fairly complex system, very far from classical mechanics and dynamics, but many scientists suggest that it is fractal dynamics that is one of the main characteristics of highly developed organisms (Wasserman EA, Kartashev H. K., Polonnikov P. I. "Fractal dynamics of the electrical activity of the brain", St. Petersburg, Nauka, 2004). The imposition of many processes of muscle, brain, electrical activity, simultaneously occurring at different levels, should, logically, lead to the lubrication of each of these processes and create difficulties for their separate recovery from the chaos of mechanical motion. Indeed, it is hard enough to believe that, for example, it is possible to identify the pulse component in a fraction of microns against the background of the speed of movement of parts of the human body at several cm / s. However, with the help of relatively simple mathematics, the authors managed to stably identify mechanical displacement finger, synchronous with the pulse wave when installing the finger in a multi-element matrix fingerprint sensor.

Human skin is a complex multilayer structure (Skin (Structure, Function, General Pathology and Therapy), edited by E. P. Frolov, Moscow, Medicine, 1982), the mechanical properties of which are rather difficult to fake, because the surface layer of the skin consists of individual keratinized cells, and almost all fakes are made of monolithic material. The fingers of a person have a certain elasticity, which is usually significantly different for people engaged in physical or mental labor. At the same time, a certain regularity was noted: when installed on the contact surface, the fingers, which can be conditionally called rigid, move more along the horizontal axis, and the fingers, which can be conditionally called soft, make more movement along the vertical axis, with the amplitude, frequency and phase of these movements are synchronized with the passage of the pulse wave in the human body. The authors were able to establish that this effect is also observed with the practical absence of a peripheral pulse at the fingertips, i.e. when the transparency of the fingers practically does not change due to the narrowing of the microcapillaries. The observed phenomenon significantly reduces the possibility of manufacturing undetectable fake carriers of biometric and, above all, fingerprint information, because copying the properties of skin elasticity in addition to all other parameters is an intractable task.

The proposed method of biometric identification is especially important for use as part of a biometric passport system, the cost of which can be several billion dollars, and the cost of the production of a fake biometric parameter may not exceed only 100 US dollars (T. Matsumoto, H. Matsumoto, K Yamada, S. Butsho, “Fipegs on Fixture Systems. Proceedings of SPIE, vol. 4677, Japan, 2002.). Moreover, if the passport system is not able to identify a fake carrier of biometric information, then all the money will be wasted on it if the passport system is not equipped with a reliable system of protection against fake biometric carriers. Naturally, it is possible to observe not only the pulse curve, but also its variability, for example, using the method of fractal dynamics (Wasserman EA, Kartashev H. K., Polonnikov P. I. "Fractal dynamics of the electrical activity of the brain", St. Petersburg, Science, 2004). In this case, of course, the measurement time also increases (up to 30 s), but the probability of skipping a fake medium becomes lower, which may be essential for specially protected objects.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows a structural diagram of the proposed method of biometric identification.

In FIG. Figure 2 shows the graphs of pulse waves obtained simultaneously for a real finger with a pronounced peripheral pulse: a) when measuring the temporal dependence of the "transparency" of the finger; b) when measuring the time dependence of the standard deviation (CKO); c) when measuring the time dependence of the mathematical center of gravity.

In FIG. Figure 3 shows the graphs of pulse waves for a practically absent peripheral pulse: a) on a real finger when measuring the temporal dependence of the "transparency" of the finger; b) on a real finger when measuring the time dependence of CKO; c) on a real finger when measuring the time dependence of the mathematical center of gravity.

In FIG. Figure 4 shows the graphs of pulse waves for a falsified biometric parameter mounted on a real finger: a) when measuring the temporal dependence of the "transparency" of the finger; b) when measuring the time dependence of CKO; c) when measuring the time dependence of the mathematical center of gravity.

In FIG. Figure 5 shows the distribution density of the signal from a fingerprint scanner at the time the pulse wave passes through the finger (a) and in the normal state (b).

An example embodiment of the invention

Here is an example of a specific implementation of the method when using a fingerprint scanner, based on the principle of obtaining a fingerprint image in the light passing through the finger. Reading information about the biometric parameter of the user is carried out by installing the user's finger in a fingerprint scanner DC21 P (see the information on the website www.elsls.ru dated 06.2004) connected to the SAMsupg REO personal computer via a parallel port operating in EPP mode. Sample information, i.e. the original print was pre-recorded in the database, as well as on a plastic card (passport) of the user (see information on the website www.elsls.ru dated 06.2004). The DC Test Pulse program, downloaded to a personal computer, initially compares the scanned fingerprint with the fingerprint stored in the database (with the sample), and then verifies the authenticity of the input biometric parameter, revealing the coincidence of the frequency components of the pulse waves using a fast Fourier transform for pulse curves obtained by various calculation methods and from different areas of the fingerprint. The measurement results are displayed by software biometric identification on the PC screen and on an external control device. Authentication and comparison of motion parameters is carried out by analyzing the resulting spectrum of fundamental frequencies in 5 seconds. Naturally, the absence of pulse displacements or their variability of more than a certain threshold of 20% generates a "No" signal when comparing motion parameters, and the system returns to a new cycle of reading biometric information. If the frequency parameters of the mechanical movement and the volume pulse coincide, the authentication is considered to be positive, and the fingerprint image obtained is compared with the sample, after which a conclusion is made about the identification result. Otherwise, when there is no mechanical movement of the fingerprint or its variability exceeds 20%, the biometric parameter is rejected as fake and the system returns to the original reading and gives a warning sound signal. The fingerprint reading frequency for the DC21 P scanner is 50 frames / s, which is quite sufficient for reliable pulse recording, and the P1600M computer power is sufficient for real-time recording of pulse waves and user identification. Let us explain the pulse curves shown in Fig 2. From this figure it follows that for most people with a clear peripheral pulse, pulse waves can be observed not only by a change in transparency inside the finger, but also by the movement of the finger vertically and horizontally. This conclusion is important enough, because allows you to capture the pulse wave not only with the help of a fingerprint scanner, a translucent finger, as was previously known, but also with the help of any other fingerprint scanners (optical, capacitive) with sufficient speed (at least 50 f / s) and resolution.

In FIG. Figure 3 shows the pulse curves for a person with a weak peripheral pulse. Studies have shown that under normal conditions, about 5 - 10% of people have this picture, and with cooling or stress, this percentage increases. These curves show that pulse waves during mechanical movement of the finger are less sensitive to peripheral pulse than a change in transparency, which means they more reliably characterize the live finger. In FIG. Figure 4 shows the pulse curves for the most complex, from the point of view of detecting a fake, fake finger when a transparent silicone thin pad with someone else's three-dimensional is installed on a real finger

(embossed) fingerprint. It follows from the figure that such a fake fingerprint carrier practically leads to the disappearance of pulsations associated with mechanical displacement. This is probably due to a significant difference in the elasticity and mechanical-inertial properties of a real finger and a false fingerprint carrier.

Thus, the absence of a mechanical pulse in the finger may indicate the presence of a fake fingerprint carrier and give a signal about the possible falsification of the system, which is especially important for passport technology, in which it is necessary to confidently distinguish the image of a fingerprint on a document from a living finger.

In FIG. Figure 5 shows the change in the density distribution of the fingerprint signal during the passage of the pulse wave, when the finger is pressed closer to the contact surface (Fig. 5a) and the distribution width and CKO are significantly reduced compared to the time when the blood density in the finger decreases (Fig. 5b). Since CKO is an integral and relative characteristic, it turned out that the temporal dependence of CKO is slightly sensitive to noise and artifacts and transmit pulse parameters well. It is possible to use other mathematical characteristics that reflect the distribution width or the distance between modes (distribution maxima) to obtain a pulse dependence.

Naturally, the implementation of the method of biometric identification described in the description does not limit the possible applications of the present invention, which can be much wider and determined by the level of technology development. As an example of biometric technology in this description was used fingerprint technology, as the most common and having the best characteristics. Naturally, it is possible to use the proposed method to protect other biometric parameters associated with the movement of the human body, for example, identification by the face or iris.

The application of this invention is possible in combination with other methods of protection against fake biometric parameters, which should ensure the reliability of the biometric system in accordance with the requirements of the market and customers.

Claims

CLAIM

1. The method of biometric identification, including reading information about the biometric parameter of the user, comparing the information obtained with the sample and protection from a fake biometric parameter, characterized in that to protect against a fake biometric parameter, measure the mechanical movement of the biometric parameter, determine the motion parameters inherent in the biometric parameter and reject the input biometric parameter as fake if the specified parameter deviates from the established norm.

2. The method according to claim 1, characterized in that a fingerprint is used as a biometric parameter, and the mechanical movement of the fingerprint is measured by the time dependence of the area of the contact surface of the fingerprint.

3. The method according to claim 2, characterized in that the contact surface area of the fingerprint is determined using the parameters of the distribution density of the signal of the biometric carrier, for example, the width of the standard deviation.

4. The method according to claim 1, characterized in that the mechanical motion of the biometric parameter is measured using the time dependence of the integral value, for example, the center of gravity of this biometric parameter.