EP1251655A1 - Method for processing and storing of biometric data - Google Patents

Abstract

The detected biometric data is represented in the form of measured quantities which are allocated to an appropriate numbering system. At least one value from a finite number of values is allocated to the measured quantity and is stored in an encoded form on an appropriate data carrier. The biometric data can be used to identify a person. Independent claims also cover computer programs and products.

Description

The invention relates to a method for processing and Storage of biometric data.

The field of biometrics is concerned with the application mathematical methods for numerical recording, Planning and evaluation of experiments in biology, Medicine and agriculture. Here, in particular Examination of the human body of interest.

A practical application example is the acquisition and mathematical description of fingerprints for their recognition, based on the mathematical description of the The course of the papillary lines and their minutiae Patterns of papillary lines are of particular interest because they clearly identify the person concerned Allow person.

For example, it is possible for customers of a bank to No longer operate an ATM using combinations of numbers but to identify them based on their fingerprints. However, this requires data, the information too play the fingerprints, for example on one Credit card or bank card must be saved. These dates must be placed on the card so that an unauthorized Access is not possible. For unauthorized access To avoid the data, the data can be encrypted can be saved.

In previous biometric methods, the biometric Data recorded and in the form of so-called measured quantities saved. The measured quantities are each represented by a quantity of measurement parameters or also by a bijective numerical Description of the measured quantity shown. With the bijective numerical description thus becomes a numerical Method chosen to suit the parameters of the measured quantity describe. When using biometric methods To achieve access protection, measured quantities first as Reference quantities saved. Then newly created measured quantities compared with the reference quantities by means of a measure, and it is determined whether it is the same Biomass deals, of which both quantities were created. It can also be taken into account with what probability it is the same biomass.

Such measured quantities are used, for example, to create databases or provided for other storage, so Representations of the measured quantities are saved. Act it is particularly protected storage, so is often a two-way encrypted image of the measured quantity is saved, but it can also be compressed parameter sets, for example be saved to save space.

A disadvantage of the known method is that the two-way encryption does not provide sufficient security.

In contrast, in the method according to the invention for Processing and storage of biometric data recorded data presented in the form of a measured quantity, the measured quantity assigned a suitable numbering system that Measured quantity at least one value from a countable quantity assigned values and this encrypts at least one value stored on a suitable data medium.

Advantageous refinements of the invention result from the subclaims.

The method according to the invention is characterized in that that after the creation of a representation of the measured quantity or the creation of numbering in later steps the measured biomass by allocating the measured quantity into suitable ones Numbering systems are carried out. Thus, one Representation of a measured quantity calculates which numbers the biomass represented by the measured quantity in suitable Numbering systems. This is done instead of or in addition for the further process of displaying the measured quantity, no matter whether this is a parameter set, a bijective numerical Description or something equivalent.

The invention is based on the knowledge that a room of possible quantities to be measured in biometric processes is densely populated or even evenly populated. Possible Measured quantities form piles around the exact representation of Biomass in the room due to measurement and mapping errors as well as measurement inaccuracies.

Numbering means that equivalence classes are formed which allow biomass to be counted using these equivalency classes be formed so that a clear Assignment of biomass to one or more equivalency classes is achieved, which are chosen so that they are allow to count the biomass. There are several for this mathematical approaches conceivable.

The steps of the process, namely storage, encryption, Decryption and detection of biometric Data can preferably be from a computer program be carried out. This has program code means to all steps of the procedure described above perform. The computer program is on a computer or a corresponding computing unit. This computing unit is, for example, in one ATM with cash card reader included.

A computer program product according to the invention has program code means on that on a computer readable disk are stored to the above Procedure. The program code means are on stored on a computer-readable data carrier. As suitable Disks can be EEPROMS and Flash Memories, however also used CD-Roms, floppy disks or hard drives become.

The recorded biometric data, including the measured quantities, can on a record carrier or data carrier be recorded. This is, for example, in one Money card included. The record carrier can measure the data resulting from the allocation of the measured quantities in suitable numbering systems result and / or this data included in encrypted form.

The record carrier according to the invention is used in the process described above. On the disk a record is recorded that at least represents an encrypted value, the minimum a value representing the numbering of a biometric data Reproduces measured quantity. The assignment of measured quantity to the value is given via an equivalence class.

The method according to the invention for using biometric Data identifying individuals provides that biometric Data of a person to be identified is recorded this data is presented in the form of a measured quantity, the measuring device is assigned to a suitable numbering system is, so that the measured quantity at least one value from a countable set of values can be assigned and this at least one value is encrypted. This encrypted Value is with a (on a record carrier) stored, also encrypted value compared, to identify the person.

When used, they are on the record carrier data contained compared with the data provided by the user for identification, for example by scanning one Fingerprint.

An example is explained in more detail below for clarification. This example illustrates the formation of numbering using three equivalence classes, formed by n-voxel grid.

It is assumed that parameter sets P _i = {p _{i, 1} , p _{i, 2} , p _{i, 3} , ...} are measured. These parameter sets represent measured quantities. It is sufficient to consider this, since in the case of a bijective numerical representation of the measured quantities, suitable parameter sets can easily be mapped from the representations. Furthermore, a suitable measure M is defined that fulfills the triangle inequality and is suitable for comparing parameter sets.

In accordance with this measure, dimensions for the space of the measured quantities are defined in such a way that d applies to all dimensions if P _i , P _k and P _l are the same in all dimensions except for d and P _i of P _{k is the} same measure as P _k of P _l , and P _i , P _k and P _{l are} different, so that P _i of P _l is twice as large as that of P _k . Of course, it is also the other way around. Dimensions and a suitable measure are defined, but often a measure already exists in an application.

As many dimensions are defined as are necessary to completely span the measuring room. Be further defined as few dimensions as possible, so no linear There are dependencies of the dimensions.

The demand for the perpendicular between the dimensions can, but does not have to be present. The term n-voxel denotes hence not necessarily n-cubes in the following. Since we not necessarily consider Euclidean spaces are the n-voxels not necessarily to be seen geometrically, in any case but isomorphic and each with the measure used equally large edges.

Suitable reference classes are then formed by choosing a dimension m ₀ such that it is greater than four times the maximum scattering factor of the piles and therefore greater than four times the dimension m, which is the maximum measure of similarity in the sense of considering the measured quantities. Such a measure m exists in every biometric method, often also implicitly, since in many cases the measure is implicitly implemented in the algorithmic solution of comparing representations of measured quantities. The dimension m ₀ is preferably chosen to be as small as possible, ie as close as possible to 4m ₀ .

It should be noted that every measuring room is finite. So there is Validity intervals in all dimensions, since each Measuring a valid measuring range in every measuring parameter Has.

The measuring space is then divided into an n-voxel grid R ₁ , the voxels having an edge length of m ₀ . The n-voxels form the equivalence classes of points in the measuring space. The problem of "overhanging" n-voxels is simply ignored, which increases the measuring space accordingly. One of the n-voxels has its origin as a corner point.

Furthermore, the measuring room is divided into a further n-voxel grid R ₂ . These n-voxels also have an edge length of m ₀ . However, the origin forms the center of an n-voxel. Again, the problem of the overhangs of the n-voxels is ignored at the edge.

Looking at R ₁ and R _{2 it} can be seen that there are still intersections in the two-dimensional between the n-voxel edges of both spaces. This is no longer the case with three dimensions. The evidence for this is known and can often be found in the literature.

If - since two-dimensional - necessary, the third space is divided into such an n-voxel grid R ₃ , so that it has the intersection points of the n-voxels from R ₁ and R ₂ as centers of its n-voxels. This grid then has twice the n-voxel density of R ₁ and R ₂ , in other words, the n-voxels of R ₃ have an edge length of 1/2 m ₀ . The method according to the invention also works in this case.

The n-voxels of the grid R ₁ , R ₂ and possibly R ₃ can now be easily numbered. It is only counted according to any system.

Each parameter set is now identified by two or three numbers represented by n-voxels. It is extremely unlikely that two sets of parameters are measured, that of different Biomass come from and still in one of the grids occupy the same n-voxel. This is due to the fact that it is extremely unlikely that two biomasses are very similar. All are based on this assumption other biometric methods, for example in identification technology be used. It is the other way round impossible that two parameter sets of the same biomass are valid be measured without not at least in one Raster the two parameter sets one and the same n-voxel occupy.

So this implementation is one double or triple numbering.

Storage is therefore sufficient in the method according to the invention of patterns that the numberings are not bijective depict.

It can thus be used in identification procedures in contrast to the processing of parameter sets or of bijective numerical representations of reference quantities Numbering can be stored one-way encrypted. It it is no longer necessary to decide the encrypted numbers. It suffices to number the new measurement quantity identify and encrypt one-way and then the encrypted Compare values. As encryption algorithms standard algorithms, such as for example MD5. Thus, without major security concerns sufficiently long hashes of numbering on electronic, magnetic or other usual data carriers, such as magnetic or chip cards, disc-shaped Data carriers or the like. at suitably chosen numbering and sufficiently large numbering range is the only known attack on this Key to get back to the original numbering the brute force attack method or by lengthy Try out what is not practical.

The method according to the invention accordingly improves all of them Applications of biometrics from a security perspective. With this procedure, biometric applications just as safe as procedures where appropriate chosen long passwords or passphrases to use come. So one of the main criticisms of security of biometric identification methods dispelled.

With the method according to the invention, it is quite conceivable numbers of fingerprints in a safe way MD5 hashed on an ATM or credit card save and use biometrics on the POS device to check whether the Fingerprint shows that the operator authorizes for using the card. This storage is compromised no longer the security of the procedure since finally the main requirement in cryptography, namely documented and to use disclosed procedures and to be sure, even with biometric methods can be easily met.

In addition, saving numbers in contrast to Storage of parameter sets to a considerable extent storage space. Often when saving parameter sets more than 125 bytes of storage space required for each parameter set. In the method according to the invention, for example, is sufficient in the double numbering shown at 64 Bit numbers already represent the memory space of 16 bytes. If one uses the property that it is sufficient, patterns Saving non-bijective images are even essential smaller amounts of storage possible. When using of 64 bit representations of the numbers and taking them into account the fact that it is very unlikely is to find two representations in the applications that in their XOR pattern at 32 bits each, i.e. a total of 32 Bit, are the same. For example, 4 bytes are sufficient Storage and comparison options. That surpasses in the minimum amount of memory also any bijective numerical Display method of a measured quantity at least same likelihood of comparison.

The attached drawing shows a triple grid. The overlap of three grids 10, 12, 14, illustrated by the use of different interrupted Lines. By means of the grid 10, 12, 14 a surface is divided into different areas.

With the help of the grid 10, 12, 14, a parameter space in where there are possible values. Every grid 10, 12, 14 defines a countable number of fields, see above that each field in each grid 10, 12, 14 is assigned a value can be. Counting in this case means a relationship between position in parameter space and one natural number, which is then encrypted one-way can be. A measured quantity can now have three values, namely assigned one in each grid 10, 12, 14 become. These three values are encrypted and serve to identify the person whose biometric data The basis of the measured quantity was.

Claims (10)

Process for processing and storing biometric Data where the data collected is in the form of a Measured quantity are shown, the measured quantity a suitable Numbering system is assigned, the measured quantity at least assigned a value from a countable set of values and this is encrypted at least one value on a suitable data medium is stored. The method of claim 1, wherein the at least one Value is one-way encrypted. The method of claim 1 or 2, wherein numbering the measured quantity using at least one equivalence class is formed. Computer program with program code means to all Steps of a method according to one of claims 1 to 3 perform when the computer program on a computer or a corresponding computing unit is executed. Computer program product with program code means which are stored on a computer-readable data medium in order to carry out a method according to one of claims 1 to 3, if the computer program on a computer or a corresponding computing unit is executed. Record carriers for use in a process according to one of claims 1 to 3, on which a data record is recorded, the at least one encrypted Value, with the at least one value representing the numbering a measured quantity representing biometric data reproduces. Method of using biometric data for identification, where biometric data of a person are recorded the recorded data is presented in the form of a measured quantity the measured quantity using a suitable numbering system is allocated so that the measured quantity at least assigned a value from a countable set of values is encrypted, this at least one value and with at least one stored on a record carrier encrypted value is compared. The method of claim 7, wherein the biometric Data can be acquired by scanning. Computer program with program code means to all Perform steps of a method according to claim 7 or 8, if the computer program on a computer or a corresponding computing unit is executed. Computer program product with program code means which are stored on a computer-readable data medium in order to perform a method according to claim 7 or 8 if the computer program on a computer or equivalent Computing unit is executed.

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