WO2003104590A1

WO2003104590A1 - Optical security system

Info

Publication number: WO2003104590A1
Application number: PCT/EP2003/006029
Authority: WO
Inventors: André Volke; Wilfried Volke
Original assignee: Codixx Ag
Priority date: 2002-06-06
Filing date: 2003-06-06
Publication date: 2003-12-18
Also published as: DE10225375B4; DE10225375A1; AU2003238487A1

Abstract

The invention relates to an optical security system that is configured as a key-lock system consisting of at least one light source (3), at least one optical sensor and at least one evaluation unit, which are located in at least one housing (5), in addition to at least one optical key. Said optical security system is characterised in that it contains a structured polariser (linear polarisation filter) as a key filter, in which at least two planes (polarisers) arranged one above the other are equipped with at least one polariser, whose surface can be structured. The polarisation characteristics of at least one of the layers (planes) are structured and the planes are aligned in relation to one another in such a way as to produce polarising areas with different polarisation directions and/or polarisation characteristics such as contrast, absorption behaviour in relation to the wavelength that is dependent on the polarisation direction and/or non-polarising areas, such as transparent or opaque areas, or areas that are strong or weak absorbers of defined wavelengths. The structured polarisation filter as the key filter is mechanically designed in such a way that it can be fitted accurately into a slot (1) that corresponds mechanically with said filter, the key filter being checked for authorisation under different illumination conditions and in different polarisation directions.

Description

Optical security system

description

The invention describes an optical security system designed as a key lock system according to the features of claim 1.

The optical security system according to the invention can be used wherever a maximum degree of security is required to prove the authenticity of the opening means and the authorization of access (proof of identification).

Known systems are, for example, lock cylinders, card readers, transponders, radio transmitters or combination locks (eg combination lock). Each of these locking systems today has one or more disadvantages in terms of security requirements. Almost every cylinder lock can be manipulated mechanically or the key can be copied. If authorizations have to be changed, the locking cylinder (lock) must be replaced. Magnetic cards can be copied very easily by standardizing the magnetic cards or with moderate effort with non-standardized cards. Chip cards can be emulated excellently with today's computer systems. Even systems (transponder, chip card or radio systems) with variable keys (e.g. as used in automotive technology) do not offer complete security, since the algorithms for key generation are forced Determined and the complexity must be limited due to the constraints of the key size, so that spying can be done with moderate effort. Optical key systems, biometric systems or holographic systems are also known.

From US 5 633 975 an optical system with a Bragg grating is known. The technology for reading out and producing a Bragg grating in a e.g. He-doped fiber is state of the art and thus the key can be copied.

A very complex opto-mechanical key system is described in US Pat. No. 5,552,587.

A scanner system with a key that can be duplicated with a normal copier is known from US Pat. No. 4,079,605 and a holographic key system is known from US Pat. No. 4,761,543. However, reading out and copying a hologram is possible with today's means. In addition, the effort is error-free

Identification with holograms is relatively high.

A system is described in US Pat. No. 4,298,792 in which the coding is implemented mechanically and with changing black / white fields acting in the infrared range. Such codes can also be copied.

In US 4,369,481 a system is described in which a crystal or a structured reflector, a laser and photodiodes are used. This system builds the

Security on the randomly generated reflection pattern. However, a reliable, reproducible analysis of these reflection patterns requires the laser to be positioned very precisely, since the smallest changes in the angle of incidence or the position of incidence can cause completely different reflections xions images are generated, the recognizability is severely limited. Computational correction of incorrect positioning is not possible here. The durability of the (micro) structures is also difficult to guarantee. The analysis with different wavelengths does not bring any additional security (apart from dispersion shifts). The polarization is also not used here. Ultimately, today's technology can also replicate microstructures using impression techniques (down to a few nanometers). If the pattern to be recognized by the lock is known (e.g. through knowledge of the lock structure and short-term possession of the key), then this pattern can be simulated by the sensor using other means, especially because only one pattern has to be simulated.

DE 42 00 332 AI describes a method and an arrangement for the non-invasive determination of substances in human body fluids. A suitable body part is penetrated and detected by means of an infrared light source, from which, for example, the

Glucose concentration in the aqueous humor can be closed. However, the relevant measurement parameters cannot be clearly assigned to a person; therefore changeable. Therefore the system described here cannot be used as an identification system.

A method and a device for encrypting and checking information in the form of a vignette is known from 195 22 928 C1. A polarizing element is irradiated and the resulting electromagnetic radiation is evaluated. This makes it possible to check the authenticity and / or the validity of the vignette. However, the device described above cannot be used for a key- or lock-based identification system. With the known solutions of the prior art, the following requirements for an effective identification system or a proof of authenticity that cannot be copied cannot be met in at least one point:

Identification and key systems have the task of being clear and secure, ie ideally fulfilling the following criteria: - The key cannot be copied by unauthorized persons (security against imitation): o it is not possible to infer the key from the lock o from the A key cannot be copied (especially for unauthorized persons) no authorization without a key (security against counterfeiting / burglary): o Lock cannot be 'cracked', e.g. by using tools o Knowledge of different keys and locks cannot be used to create others Keys are used to flexibly assign the releases / authorizations associated with each key (eg locking a single key in the event of loss) without changing the lock, as well as the ability to use many keys that are clearly identifiable in each lock without loss of security: o Lock needs when changing permissions for e individual or all keys are not changed; each key has its own identity, to which the authorizations in the evaluation unit can be assigned The object of the invention is to describe an optical security system in the form of a key lock system with which the disadvantages of the prior art are avoided, which cannot be successfully manipulated and a required key cannot be imitated, when trying out or knowing the key not to unauthorized opening and its structure can be kept relatively simple.

This object is achieved by an optical security system with the features of claim 1.

The optical security system is characterized in that it contains a structured polarizer (linear polarization filter) as a key filter, in which at least two levels (polarizers) arranged one above the other are formed with at least one polarizer that can be structured in the surface, at least one of the layers ( Levels) is structured in terms of its polarization properties and the levels are aligned with one another in such a way that polarizing areas with different polarization directions and / or polarization properties such as contrast, polarization direction-dependent absorption behavior with respect to the wavelength and / or non-polarizing areas such as transparent or opaque or for defined areas Wavelengths result in regions of arbitrarily strong absorption, the structured polarization filter being mechanically designed as a key filter in such a way that it fits precisely into a mechanically corresponding one n slot can be inserted in which the

Key filter is checked for authorization under different lighting conditions and polarization directions. With the present invention, a key filter can be realized that side by side in one plane areas of different polarization directions, areas of different wavelengths of maximum polarization with the same or different polarization direction, areas without polarization and areas of strong absorption.

The invention circumvents the disadvantages of the prior art by proposing a key-lock system which is based on an optical coding in which the same cannot be copied or a valid one without complex aids and technological know-how and knowledge of the key Key cannot be generated. This is achieved by using a structured polarization filter as a key with the following properties: structured structured polarization filter with structures arranged side by side in one plane (in μm dimensions) with different polarization directions (preferably rotated 90 ° to one another) and / or structures arranged side by side in a plane (in μm dimensions) with different absorption properties regarding the wavelength as well as an analysis system with the following structure: - in one or more defined switchable polarization directions (preferably two linearly polarized light arranged at 90 ° to each other) emitting light source which has one or more different defined switchable wavelength ranges and / or one or more different, emits switchable monochromatic wavelengths,

Key slot for the precise insertion of the key and as a mechanical obstacle against unauthorized manipulation (even such cannot lead to access authorization), Photosensor unit, optionally optics for imaging the structures arranged next to one another in one plane onto the photosensor unit, which is preferably designed in the form of a CCD array, is arranged in the beam path light source ^ keyhole photosensor unit and - evaluation unit for identifying the Compares the key data of the photosensor unit with the comparison data stored there and grants or rejects the authorization.

Due to the small possible structural dimensions, a very large variety of different structures is possible. An execution in which two or more keys are required to obtain authorization is possible. For this purpose, either certain keys have to be inserted into the slot in a defined time and / or sequence and the evaluation unit evaluates this, or several keys have to be inserted into one or more slots at the same time, which are designed so that they become one in the beam path

Combine keys. In the simplest case, the structures can be arranged side by side or one behind the other in one level (key 1 front half structured, rear half transparent, key 2 reversed accordingly), other arrangements in one level even with more than 2 keys are possible, especially if the beam path in the area of the key slots is designed as a parallel beam path through imaging optics.

Advantageous embodiments of the invention are described in the subclaims.

The invention is explained in more detail below in an exemplary embodiment of an optical locking system. In the accompanying drawing: 1: the schematic representation of an outer housing with the necessary components for the system contained therein and the slot for inserting the optical key (structured polarizing filter),

2: the schematic representation of the structure of the key and the slot design,

3: the schematic representation of a structured polarizing filter in a frame for guidance,

Fig. 4: the schematic representation of a

Arrangement of optical components for generating the various illuminations for analysis and

5: the graphic representation of the detection of the smallest tolerance limits when using the system.

1 and 2 schematically show the components necessary for implementing the security system according to the invention in a housing 5. The components slot 1 for introducing a structured polarizing filter 7 (FIGS. 2, 3) as an optical key and a protective glass 6 are visible from the outside.

Optical systems 2, a light source 3, a photosensor arrangement 4 and an evaluation device (not shown) are arranged in the housing 5, not visible from the outside.

As shown in FIGS. 1 and 2, the slot 1 is covered with the protective glass 6 so that only one narrow opening for the introduction of the structured polarizing filter 7 remains open.

The structured polarizing filter 7 as the key element is, as shown in FIG. 3, enclosed in a frame 8 which at the same time serves for guiding and stabilizing when inserted into the lock slot 1.

FIG. 4 shows an example of the optical system 2, which is formed here from primary light sources 10, 11, from polarization filters 12, from a color filter 13 and from a diffusing screen 14. The lens must not affect the polarization of the light. Due to the properties of Ag colloid-containing polarizing glasses, the possible wavelengths are in the range of 240nm- 1500nm. This provides a broad spectrum for different lighting conditions for a safe analysis.

After insertion of the key 7, the key 7 is irradiated with light of at least a defined wavelength and / or a defined wavelength range and a defined polarization direction such that the light modified by the key 7 falls on the photosensor 4. The intensity distribution or mapping of the key 7 at the wavelengths and the direction of polarization onto the photosensor unit 4 is compared with a target image stored in the evaluation unit (not shown). The same is repeated with other, defined polarization directions and / or wavelength ranges and / or wavelengths. If all the target-actual comparisons are positive, the key 7 is recognized and the release can take place. The positioning accuracy of the key is of secondary importance, since the position of the key image can be corrected using common computer science methods. Because the image acquisition and the analysis are very good can be done quickly, the key recognition takes place reliably within a very short time (<1 second).

The comparison data to be stored in the evaluation unit can be obtained by calculating the intensity ratios of the structures and relative adaptation to the absolute brightness.

A much simpler way with greater certainty, however, is "teaching", in which reference recordings are carried out once, which then serve as comparison data. This variant is simple to implement and gives the possibility of random tolerances in the production of the structured polarization filter 7, which are steep Rises in the absorption flanks become clearly apparent for the uniqueness of the key 7. This makes reproduction impossible even with the current mastery of the technology, as shown in Fig. 5. An absorption curve 15 is shown in Fig. 5. A small difference 16 in the wavelength is already associated with a sufficiently distinctive and thus recognizable difference 17 in the absorption.

The security according to the above requirements is guaranteed by the following points:

1. Key 7 cannot be copied by unauthorized persons: There is currently only one manufacturer of suitable structured, dichroic polarization filters for the UV / VIS / NIR range (340-390, 450-1500nm) worldwide. This is due on the one hand to the necessary manufacturing technology (high investment costs) and on the other hand to the necessary technological know-how (several, non-trivial manufacturing steps) for these filters. Furthermore, non-reproducible tolerances for uniqueness can easily be exploited.

2. From the lock, formed by components 2 to 6, it is not possible to draw any conclusions about the key 7, since the evaluation of the key 7 takes place with the aid of comparison data stored in the evaluation unit, which, however, are arranged inaccessible in a protected area no data or comparison pattern can leak to the outside. Only the light required for the analysis can be analyzed from the outside with moderate effort, but does not allow any conclusions to be drawn about the coded structures in the filter. This is not a security-relevant fact, since the protection is based on the uniqueness and complexity of the key and not on the secrecy of the functional principle. In addition, the duration and sequence of the lighting can be random, e.g. controlled by the evaluation unit can be varied. Manipulations can be recognized based on the response times, only structured polarization filters react as passive components without delay.

3. No copy of key 7 can be created, especially for unauthorized persons:

The following three prerequisites are necessary to copy or generate a key: 3.1 precise knowledge of the optical codes (position and shape of the absorption band and their polarization properties with regard to the wavelength; structuring (arranged next to one another in one plane) of the same) of the original key 3.2 Knowledge of the manufacturing technology for structured polarization filters (non-trivial)

3.3 Availability of the system technology for this technology (very high price or system technology not available)

However, these requirements are very difficult to meet for the following reasons:

3.3.1 This is not possible without expensive and complex analysis technology (microspectrophotometer) and possession of the key (as well as knowledge of the physical basics); a qualitatively at least equivalent structure as the lock itself is necessary, u. However, it may not be sufficient. If the accuracy corresponds exactly to that of the real analysis system, but losses or deteriorations naturally occur in the further course, this can lead to an insufficient result, so that a key copy made afterwards is recognized as not authorized.

3.3.2 There is currently no such polarization filter structured worldwide; the manufacturing technology is not state of the art and also not obvious. There are only a few alternative technologies and they are similar in terms of effort and know-how.

3.3.3 Numerous process steps in non-standard systems are required for production. Both the know-how of these systems and the amount of investment currently represent effective protection against imitation

(comparable to the protection of banknotes).

4. No authorization without a key (security against counterfeiting / burglary): Since the analysis of the key verifies the non-mimicable properties (structures arranged side by side in a plane with different polarization direction and wavelength-dependent absorption), exactly such a key with exactly the same properties is necessary.

5. The lock cannot be "cracked", e.g. by using tools:

There are two basic options for breaking in:

5.1 Simulation of a key

5.2 Manipulation of the lock

Both options could also be combined. The solution presented here effectively prevents both options and combinations:

5.3 A simulation would have to be created for each of the wavelengths (combinations) used, hereinafter referred to as primary lighting, and for each tested polarization plane the exact same image as would be generated by the original key. The fact that these images differ greatly is an essential property of the structured, dichroic polarization filter. A simulation would therefore have to mirror all checked, very different images to the photo sensor (e.g. CCD). Since the testing of the different polarization levels and different primary illuminations can take place very quickly one after the other, simple methods such as quick exchange of the key are not possible, especially if the order of the primary illuminations and

Polarization directions are chosen randomly by the lock. In any case, a delay to the practically inertia-free reaction of the original key can be determined and is recognized by the photo sensor. An optical component that is inertia between the necessary structures can also be changed is also not known. If, instead of the polarized Schlossbeleuchtung another lighting used, for example different monochromatic light sources, ^'which can be switched fast enough, and as a key would be an optical filter is used, the color filter characteristics are designed so that these at the respective Anstatt- If the lighting produces the same intensity distribution as a known original key on the photo sensor used, a simulation would be successful. A prerequisite for this, however, is a precise knowledge of the reaction of the photosensor to the use of unpolarized instead of polarized light and of the different other wavelengths, two polarization directions of a primary lighting would have to be replaced by at least one other primary lighting, as well as a precise knowledge of the original key as well as the exact knowledge of the primary illuminations and polarization directions used as well as the

Real-time detection of the respectively used and real-time switching of those necessary for the simulation. Furthermore, such a multi-color selective filter would also have to be calculated and manufactured. Such tests can be excluded by simply checking the correct polarization direction of the primary lighting and / or additional color filters that change light other than that of the primary light sources used. Another complicating problem is the placement of the external light source (flat) and the replacement filter in the narrow key gap. This leaves only a copy of the key, which, however, is subject to the above, strongly securing restrictions. 5.4 The structure of the part of the lock that is accessible from the outside is very simple and can be designed to be safe in that a destruction of whatever kind results in the outer part not being released by the evaluation unit installed in the secured room. The photo sensor responsible for security to the outside, whose interface to the evaluation unit could simulate with a great deal of effort and provided extensive knowledge (original key, primary light sources and polarization directions used and their sequence, bus system / protocol used for evaluation electronics, imaging optics) can be manipulated by manipulating the lock become accessible. However, such an intervention can be monitored and recognized. Even if it succeeds, the effort remains immense and the requirements are difficult to achieve, so that security is practically guaranteed here too. Other manipulations are not very promising, since the correct signal sequence must ultimately reach the evaluation unit. However, this is practically not derivable from the key (see above), only knowledge of the internal evaluation algorithms and the comparison data, which, however, are safe in the protected space, would theoretically make this possible. Larger, necessary manipulations on the lock can be recognized with known methods. In addition, the distance between the key slot and the CCD sensor can be chosen to be very large by means of suitable imaging optics with lenses and / or mirrors, so that the sensor is guaranteed to be inaccessible in the secured area and is inaccessible from outside.

6. Knowledge of different keys and lock cannot be used to generate other keys: The structures of the individual keys can be so randomly different that they are not related to one another. Only the comparison data stored in the evaluation unit are decisive. Therefore, no further valid key can be generated without expanding the comparison data.

7.Flexible allocation of the releases / authorizations associated with each key (e.g. locking a single key in the event of loss) without changing the lock:

Since each key is uniquely assigned a number of comparison data corresponding to the primary illuminations and polarization directions in the evaluation unit, the corresponding attributes such as validity, authorization levels, etc. can be assigned to this data independently of all other keys. By changing these attributes, actions such as Lock a key, change the authorization level. This is a simple software operation that has to be carried out on the evaluation unit arranged in the protected room. It is not necessary to change the key or lock.

8. The lock does not need to be changed when changing authorizations: see point 7. LIST OF REFERENCE NUMBERS

1 slot

2 Optical system for beam shaping and imaging

3 light source

4 photo sensor (CCD)

5 housing (solid and only slot 1 is open to the unsecured area)

6 ^' protective glass

7 Structured polarizing filter

8 framework and guidance

9

10 primary light source

11 primary light source

12 polarization filters

13 color filters

14 lens

15 absorption curve

16 Difference in the absorption properties of the filters

17 detected difference in the evaluation unit

18 wavelength

Claims

claims

1. Optical security system consisting of at least one light source (3), at least one optical sensor and at least one evaluation unit which are arranged within at least one housing (5) and at least one optical key, characterized in that the optical key has at least one structured polarization filter ( 7) and can be arranged in the key slot in such a way that the optical key shines through from the light source (3) and is at least partially imaged on the evaluation unit.

2. Optical security system according to claim 1, characterized in that the structured polarizer (7) (linear polarization filter) used as a key has at least two structured levels (polarizers) arranged one above the other, at least one of the levels being structured in such a way in its polarization properties and the planes are aligned with one another in such a way that polarizing areas with different polarization directions and / or ^" polarization properties such as contrast, absorption behavior dependent on polarization direction with respect to the wavelength and / or non-polarizing areas such as transparent or opaque areas or areas strongly absorbing for defined wavelengths result The structured polarization filter (7) is mechanically configured as a key filter in such a way that it can be inserted precisely into a mechanically designed key slot.

3. Optical security system according to one of the preceding claims, characterized in that the light source (3) is adjustable with respect to its wavelength and / or wavelength ranges and / or with respect to its direction of polarization and / or the optical sensor has at least one photo sensor (4) and / or the optical security system has a secure transmission path to the evaluation unit for identifying the data from the optical sensor with comparison data and / or the housing (5) has a key slot.

4. Optical security system according to one of the preceding claims, characterized in that for identification of the key, the different wavelengths and / or wavelength ranges and / or polarization directions are switched on one after the other for irradiation of the key, the data determined by the image of the key on the sensor are transmitted to the evaluation unit and are compared there with comparison data and if the data are substantially identical, the authenticity is confirmed.

5. Optical security system according to one of the preceding claims, characterized in that for the analysis of both polarization filter directions in the beam path between the light source (3) and key a rotatable, electrically switchable TN cell is introduced.

6. Optical security system according to one of the preceding claims, characterized in that the optical sensor is designed as a CCD cell (4).

7. Optical security system according to claim 6, characterized in that the CCD cell (4) is three-colored.

8. Optical security system according to one of the preceding claims, characterized in that the key is sequentially examined with different wavelengths and is analyzed by means of a monochrome CCD cell (4) and the CCD information read is compared with stored comparison patterns.

9. Optical security system according to one of the preceding claims, characterized in that a receiver, which measures the brightness, and an analysis filter are provided, with the combination of which the authoritative brightness values for different colors and polarization directions arise in the beam path.

10. Optical security system according to claim 9, characterized in that several different areas are defined in the polarization filter (7), the brightness values of which are required for different colors and polarization directions for authorization.

11. Optical security system according to one of the preceding claims, characterized in that for opening at least two structured polarization filters (7) are required in specified periods and / or order for authorization.

12. Optical security system according to one of the preceding claims, characterized in that for opening at least two structured polarization filters (7) have to be inserted simultaneously into slots provided for authorization.

13. Optical security system according to one of the preceding claims, characterized in that the smallest, non-reproducible manufacturing tolerances are used in such a way that they are necessary for recognition, preferably by teaching the key by means of reference recordings, so that copying of the key is impossible.

14. Optical security system of at least one of claims 1 to 9, characterized in that only one polarization direction is provided in the polarization filter (7).

15. Optical security system according to one of the preceding claims, characterized in that the key slot has a slot.

16. Optical security system according to claim 15, characterized in that the slot is formed by a frame (8) and at least one protective glass (6).

17. Optical security system according to one of the preceding claims, characterized in that the optical security system has optically imaging elements (2) which are arranged between the light source (3) and the key slot or between the key slot and the optical sensor.

18. Optical security system according to one of the preceding claims, characterized in that the housing (5) is secured against unauthorized opening or manipulation.

19. Optical security system according to one of the preceding claims, characterized in that the light source (3) has at least one primary light source (10, 11), a polarization filter (12), a color filter (13) and a lens (14).