WO2006013528A1 - Information carrier with copy protection, system for reading such an information carrier - Google Patents

Information carrier with copy protection, system for reading such an information carrier Download PDF

Info

Publication number
WO2006013528A1
WO2006013528A1 PCT/IB2005/052468 IB2005052468W WO2006013528A1 WO 2006013528 A1 WO2006013528 A1 WO 2006013528A1 IB 2005052468 W IB2005052468 W IB 2005052468W WO 2006013528 A1 WO2006013528 A1 WO 2006013528A1
Authority
WO
WIPO (PCT)
Prior art keywords
information carrier
detector
array
data
light spots
Prior art date
Application number
PCT/IB2005/052468
Other languages
French (fr)
Inventor
Robert Hendriks
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2006013528A1 publication Critical patent/WO2006013528A1/en

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/28—Indicating or preventing prior or unauthorised use, e.g. cassettes with sealing or locking means, write-protect devices for discs
    • G11B23/281—Indicating or preventing prior or unauthorised use, e.g. cassettes with sealing or locking means, write-protect devices for discs by changing the physical properties of the record carrier
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/00731—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a digital rights management system for enforcing a usage restriction
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/14—Heads, e.g. forming of the optical beam spot or modulation of the optical beam specially adapted to record on, or to reproduce from, more than one track simultaneously
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/005—Reproducing
    • G11B7/0053—Reproducing non-user data, e.g. wobbled address, prepits, BCA
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/00736—Auxiliary data, e.g. lead-in, lead-out, Power Calibration Area [PCA], Burst Cutting Area [BCA], control information
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection

Definitions

  • the invention relates to an information carrier with copy protection, and to a system for reading such an information carrier.
  • the invention may be used in the field of optical storage.
  • This solution proposes that an irradiating light beam is applied to the optical structure.
  • the diffractive pattern i.e. a so-called speckle pattern
  • the output signal generated in response is then detected, and compared to a reference pattern. According to the result of this comparison, access to the content of the information carrier is given.
  • the speckle pattern can be seen as the output of a physical One- Way Function (OWF), the inputs of which are the internal microstructure of the optical structure and the irradiating beam of light.
  • An OWF is a function easy to evaluate in the forward sense, but generally unfeasible to compute in the reverse direction, and wherein the output domain is very large and the input domain is even much larger.
  • An attempt to clone an optical structure could be based on its physical observation, or on its behavioral observation.
  • the information carrier according to the invention comprises:
  • a data area intended to generate an output light beam representative of said data in response of an array of light spots
  • a diffractive structure intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure being placed beside said data area and at a different depth in said information carrier.
  • the diffractive structure is easily accessible by the array of light spots, the cryptographic key may be easily recovered. Moreover, inserting during manufacture the diffractive structure in the information carrier in such a way leads to a cost-effective solution.
  • this system for reading an information carrier comprising a data area and a diffractive structure representative of a cryptographic key
  • said system comprising: an optical element for generating an array of light spots intended to be applied to said information carrier, - a detector for detecting the output light beam generated by said information carrier in response of said array of light spots, means for changing the relative position of said optical element and said detector, with respect to said diffractive structure, so as to align said optical element and detector with said data area in view of detecting data on said detector, or to align said optical element and detector with said diffractive structure in view of detecting said cryptographic key on said detector.
  • the same light generation means and detector are used either for detecting the cryptographic key of the information carrier, or for reading data on the data area, which allows a compact implementation, and which leads to a cost-effective solution.
  • the reading system further comprises detection means for detecting markers placed on said information carrier, and actuation means for positioning said information carrier from said markers.
  • the expected reference diffractive pattern which characterizes the cryptographic key can thus be more easily and accurately detected.
  • the reading system further comprises a liquid crystal layer placed at the input of said optical element for modifying the optical characteristics of the array of light spots applied to said diffractive structures.
  • the cryptographic key is derived from only one expected diffractive pattern, it is now derived from the recognition of a plurality of expected diffractive patterns, which reinforces the digital right management of the information carrier.
  • Fig.l depicts a system for reading an information carrier
  • Fig.2 depicts a cross-section of an information carrier according to the invention
  • Fig.3 depicts a detailed view of said system for reading an information carrier
  • Fig.4 illustrates by an example the principle of macro-cell scanning of an information carrier
  • Fig.5 depicts a first arrangement for scanning an information carrier
  • Fig.6 depicts a second arrangement for scanning an information carrier
  • Fig.7 depicts detailed elements of said second arrangement
  • Fig.8 depicts a reading system according to the invention
  • Fig.9 depicts a cross-section of a preferred information carrier according to the invention
  • Fig.10 illustrates various apparatus and devices for reading an information carrier according to the invention.
  • Fig.l depicts a three-dimensional view of a reading system according to the invention.
  • This system comprises an information carrier 101.
  • the information carrier 101 comprises a data area DA intended to generate an output light beam representative of said data in response of an array of light spots 102.
  • the data area DA comprises a set of square adjacent elementary data areas having size referred to as s and arranged as in a matrix. Data are coded on each elementary data area via the use of a material intended to take different transparency levels, for example two levels in using a material being transparent or non-transparent for coding a 2-states data, or more generally N transparency levels (for example N being an integer power of 2 for coding a 2 log(N)-states data).
  • the information carrier 101 also comprises a diffractive structure DS intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure being placed beside said data area.
  • the diffractive structure DS is made for example of a three-dimensional structure of different refractive indices.
  • the diffractive structure DS is included in the information carrier during its manufacture. The characteristics of this diffractive structure are also known in particular by the reading apparatus so that it is able to perform a comparison between a diffractive pattern generated by the diffractive structure DS, and a reference diffractive pattern stored in said reading apparatus.
  • Fig.2 depicts a cross-section of an information carrier according to the invention.
  • the data area DA must always be imaged on the detector when the light spots are focussed on said data area.
  • the distance between the data area DA and the detector is such that the sharpness of the light beam outputted by the data area DA and detected by the detector is maximal.
  • the diffractive structure DS itself must not be imaged on the detector when the light spots have the same focus plane as when they are applied to the data layer. Only the diffractive pattern must be imaged so that the encryption key plays fully its role.
  • the data area DA and the diffractive structure DS are placed at a different depth in the information carrier 101. In other words, a depth difference ⁇ e between these two elements is necessary.
  • the data area DA and the diffractive structure DS are included in a transparent layer TL made, for example, of plastic.
  • This system also comprises an optical element 104 for generating the array of light spots 102 which are intended to be applied to said elementary data areas.
  • the optical element 104 advantageously correspond to a two-dimensional array of apertures at the input of which the coherent input light beam 105 is applied.
  • the apertures correspond for example to circular holes having a diameter of 1 ⁇ m or much smaller.
  • the array of light spots 102 is generated by the array of apertures in exploiting the Talbot effect which is a diffraction phenomenon working as follows.
  • a coherent light beam such as the input light beam 105
  • an object having a periodic a diffractive structure such as the array of apertures
  • the diffracted lights recombines into identical images of the emitters at a plane located at a predictable distance z ⁇ from the diffracting structure. This distance z ⁇ is known as the Talbot distance.
  • Exploiting the Talbot effect allows generating an array of light spots of high quality at a relatively large distance from the array of apertures (a few hundreds of ⁇ m, expressed by z(m)), without the need of optical lenses.
  • This allows inserting for example a cover layer between the array of aperture and the information carrier 101 for preventing the latter from contamination (e.g. dust, finger prints ).
  • this facilitates the implementation and allows increasing in a cost-effective manner, compared to the use of an array of micro-lenses, the density of light spots which are applied to the information carrier.
  • Each light spot is intended to be successively applied to an elementary data area. According to the transparency state of said elementary data areas, the light spot is transmitted (not at all, partially or fully) to a CMOS or CCD detector 103 comprising pixels intended to convert the received light signal, so as to recover the data stores on said elementary data area.
  • one pixel of the detector is intended to detect a set of elementary data, said set of elementary data being arranged in a so-called macro-cell data, each elementary data area among this macro-cell data being successively read by a single light spot of said array of light spots 102.
  • This way of reading data on the information carrier 101 is called macro-cell scanning in the following and will be described after.
  • Fig.3 depicts a partial cross-section and detailed view of the information carrier 101, and of the detector 103.
  • the detector 103 comprises pixels referred to as PX1-PX2-PX3, the number of pixels shown being limited for facilitating the understanding.
  • pixel PXl is intended to detect data stored on the macro-cell data MCl of the information carrier
  • pixel PX2 is intended to detect data stored on the macro-cell data MC2
  • pixel PX3 is intended to detect data stored on the macro-cell data MC3.
  • Each macro-cell data comprises a set of elementary data.
  • macro-cell data MCl comprises elementary data referred to as MCIa-MCIb-
  • FIG.4 illustrates by an example the macro-cell scanning of the information carrier 101.
  • Data stored on the information carrier have two states indicated either by a black area (i.e. non-transparent) or white area (Le. transparent).
  • a black area corresponds to a "0" binary state while a white area corresponds to a "1" binary state.
  • the pixel When a pixel of the detector 103 is illuminated by an output light beam generated by the information carrier 101, the pixel is represented by a white area. In that case, the pixel delivers an electric output signal (not represented) having a first state. On the contrary, when a pixel of the detector 103 does not receive any output light beam from the information carrier, the pixel is represented by a cross-hatched area. In that case, the pixel delivers an electric output signal (not represented) having a second state.
  • each macro-cell data comprises four elementary data areas, and a single light spot is applied simultaneously to each set of data.
  • the scanning of the information carrier 101 by the array of light spots 102 is performed for example from left to right, with an incremental lateral displacement which equals the period of the elementary data areas.
  • the central light spot is applied to a non-transparent area so that the corresponding pixel is in the second state, while the two other light spots are applied to transparent areas so that the two corresponding pixels of the detector are in the first state.
  • Elementary data which compose a macro-cell opposite a pixel of the detector are read successively by a single light spot.
  • the scanning of the information carrier 101 is complete when the light spots have each been applied to all elementary data area of a macro-cell data facing a pixel of the detector. This implies a two-dimensional scanning of the information carrier.
  • a scanning of the information carrier by the array of light spots is done in a plane parallel to the information carrier.
  • a scanning device provides translational movement of the light spots in the two directions x and y for scanning all the surface of the information carrier.
  • the scanning device corresponds to an H-bridge.
  • the optical element generating the array of light spots (i.e. the array of micro-lenses or the array of apertures) is implemented in a first sledge 501 which is movable along the y axis compared to a second sledge 502.
  • the first sledge 501 comprises joints 503-504-
  • the second sledge 502 is movable along the x axis by means of joints 511-512-513-514 in contact with guides 509-510.
  • the sledges 501 and 502 are translated by means of actuators (not represented), such as by step-by-step motors, magnetic or piezoelectric actuators acting as jacks.
  • the scanning device is maintained in a frame 601.
  • the elements used for suspending the frame 601 are depicted in a detailed three- dimensional view in Fig.7. These elements comprise: a first leaf spring 602, - a second leaf spring 603, a first piezoelectric element 604 providing the actuation of the scanning device 601 along the x axis, a second piezoelectric element 605 providing the actuation of the scanning device 601 along the y axis.
  • the second solution depicted in Fig.6 has less mechanical transmissions than the H- bridge solution depicted in Fig.5.
  • the piezoelectric elements, in contact with the frame 601, are electrically controlled (not represented) so that a voltage variation results in a dimension change of the piezoelectric elements, leading to a displacement of the frame 601 along the x and/or the y axis.
  • the position Posl depicts the scanning device 601 in a first position, while the position Pos2 depicts the scanning device 601 in a second position after translation along the x axis.
  • the flexibility of the leaf springs 602 and 603 is put in evidence.
  • a similar configuration can be built with four piezoelectric elements, the two extra piezoelectric elements replacing the leaf springs 602 and 603. In that case, opposite pair of piezoelectric elements act together in one dimension in the same way as an antagonist pair of muscles.
  • the system according to the invention also comprises means for changing the relative position of said optical element 104 and said detector 103, and said diffractive structure DS, respectively, so as to align said optical element 104 and said detector 103 with said data area DA in view of detecting data on said detector, or to align said optical element and detector with said diffractive structure DS in view of detecting said cryptographic key on said detector.
  • the system may comprise, for example, actuation means (e.g. an actuator such as a linear servo motor, not shown) for displacing said optical element 104 and said detector 103 in a first position in front of said data area DA in view of detecting data on the detector (as illustrated by the top Fig.8), and in a second position in front of said diffractive structure DS in view of detecting said cryptographic key on the detector (as illustrated by the bottom Fig.8).
  • actuation means e.g. an actuator such as a linear servo motor, not shown
  • the cryptographic key may be analyzed by conventional processing means in charge of extracting optical characteristics in the diffractive pattern (e.g. by means of a signal processor executing code instructions reflecting the steps of an algorithm).
  • Fig.9 depicts an improved information carrier 901 according to the invention.
  • the information carrier 901 differs from the information carrier depicted in Fig.2 in that it additionally comprises markers (Ml, M2) intended to be used for controlling the alignment between said array of light spots 102 and said diffractive structure DS.
  • Markers may be made of non-transparent areas which are expected to generate a known pattern (e.g. a black dot) at a known position (e.g. on a specific pixel) on the detector when the information carrier is accurately positioned in the reading system.
  • the reading system comprises detection means for detecting the markers
  • Said detection means comprises the detector, and also analysis means for extracting said known pattern at a known position.
  • the information carrier is first accurately positioned in the reading system with the help of said markers.
  • the expected reference diffractive pattern which characterizes the cryptographic key can thus be more easily detected.
  • the system comprises a Liquid Crystal (LC) layer placed at the input of the array of apertures 104.
  • the LC layer aims at modifying the phase profile of the input light beam 105 according to various known and predetermined phase profiles (e.g. linear/quadratic phase profile, or a more complex phase profiles) set by the reading system. As a consequence, the optical characteristics of the array of light spots applied to the diffractive structures DS are modified.
  • phase profiles e.g. linear/quadratic phase profile, or a more complex phase profiles
  • phase profiles are successively defined by addressing accordingly the matrix of LC elements.
  • a first phase profile is defined and applied to the diffractive structure DS in view of detecting a first expected diffractive structure
  • a second phase profile is defined and applied to the diffractive structure DS in view of detecting a second expected diffractive structure, and so on.
  • the cryptographic key is derived from only one expected diffractive pattern, it is now derived from the matching between a plurality of couples (detected diffractive patterns, expected diffractive patterns). This reinforces the digital right management of the information carrier.
  • the system according to the invention may advantageously be implemented in a reading apparatus RA (e.g. home player apparatus ...), a portable device PD (e.g. portable digital assistant, portable computer, a game player unit%), or a mobile telephone MT.
  • a reading apparatus RA e.g. home player apparatus
  • PD portable digital assistant
  • portable computer e.g. portable computer
  • game player unit e.g. portable computer
  • mobile telephone MT e.g. portable digital assistant, portable computer, a game player unit
  • These apparatus and devices comprise an opening (OP) intended to receive an information carrier 1001 as depicted by Fig.2 and/or Fig.9, and a system as depicted by Fig.l and Fig.8 in view of recovering data and the cryptographic key stored on said information carrier.
  • OP opening

Abstract

The invention relates to an information carrier (101) intended to store data, said information carrier comprising: - a data area (DA) intended to generate an output light beam representative of said data in response of an array of light spots, - a diffractive structure (DS) intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure (DS) being placed beside said data area (DA) and at a different depth in said information carrier (101). The invention also relates to a system for reading such an information carrier (101). Use: Digital right management.

Description

"Information carrier with copy protection, system for reading such an information carrier"
FIELD OF THE INVENTION
The invention relates to an information carrier with copy protection, and to a system for reading such an information carrier.
The invention may be used in the field of optical storage.
BACKGROUND OF THE INVENTION
With the important use of content distribution supports such as CD or DVD, copy protection, or more generally digital right management (DRM) have become an important issue. Not only data must be protected, but also the copy protection mechanism itself must be robust to any cloning.
Recently, solutions based on the use of a specific optical structure included in an information carrier have been proposed. This solution proposes that an irradiating light beam is applied to the optical structure. The diffractive pattern (i.e. a so-called speckle pattern) of the output signal generated in response is then detected, and compared to a reference pattern. According to the result of this comparison, access to the content of the information carrier is given.
What makes an optical structure substantially impossible to clone is the way the characteristic information is derived from it together with the way the optical structure is produced. The speckle pattern, and consequently the characteristic information, can be seen as the output of a physical One- Way Function (OWF), the inputs of which are the internal microstructure of the optical structure and the irradiating beam of light. An OWF is a function easy to evaluate in the forward sense, but generally unfeasible to compute in the reverse direction, and wherein the output domain is very large and the input domain is even much larger. An attempt to clone an optical structure could be based on its physical observation, or on its behavioral observation. An optical structure could in principle be observed with a noninvasive tomographic imaging technique, however equipment presently available does not allow for the micro fabrication of the internal microstructure to the required level of detail. The possibility to deduce the internal microstructure of the optical structure, based on its behavior, i.e. speckle pattern and characteristic information as a response to a given irradiating beam is ruled out due to the properties of an OWF.
The possibility to produce an optical structure, potentially different from the original one, but having exactly the same behavior is also unfeasible, given the large number of possible values for the parameters defining the coherent beam of light, and the computational complexity of reconstructing an optical structure having a known behavior.
Further detailed considerations on the properties of physical OWF, and on the substantial impossibility to clone an optical structure, or to reconstruct an optical structure with a known behavior, or even to fool a system for access control of user-information based on optical structure are brought in the article "Physical One- Way Functions" Ravikanth Pappu et al., Vol. 297 SCIENCE, 20/09/2002.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the invention to propose an improved information carrier comprising a data area and a diffractive structure representing a cryptographic key.
To this end, the information carrier according to the invention comprises:
- a data area intended to generate an output light beam representative of said data in response of an array of light spots, - a diffractive structure intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure being placed beside said data area and at a different depth in said information carrier.
Since the diffractive structure is easily accessible by the array of light spots, the cryptographic key may be easily recovered. Moreover, inserting during manufacture the diffractive structure in the information carrier in such a way leads to a cost-effective solution.
It is also an object of the invention to propose a system for reading such an information carrier. To this end, this system for reading an information carrier comprising a data area and a diffractive structure representative of a cryptographic key, said system comprising: an optical element for generating an array of light spots intended to be applied to said information carrier, - a detector for detecting the output light beam generated by said information carrier in response of said array of light spots, means for changing the relative position of said optical element and said detector, with respect to said diffractive structure, so as to align said optical element and detector with said data area in view of detecting data on said detector, or to align said optical element and detector with said diffractive structure in view of detecting said cryptographic key on said detector.
The same light generation means and detector are used either for detecting the cryptographic key of the information carrier, or for reading data on the data area, which allows a compact implementation, and which leads to a cost-effective solution.
In a preferred embodiment, the reading system further comprises detection means for detecting markers placed on said information carrier, and actuation means for positioning said information carrier from said markers. The expected reference diffractive pattern which characterizes the cryptographic key can thus be more easily and accurately detected.
In a preferred embodiment, the reading system further comprises a liquid crystal layer placed at the input of said optical element for modifying the optical characteristics of the array of light spots applied to said diffractive structures.
Instead the cryptographic key is derived from only one expected diffractive pattern, it is now derived from the recognition of a plurality of expected diffractive patterns, which reinforces the digital right management of the information carrier.
Detailed explanations and other aspects of the invention will be given below. BRIEF DESCRIPTION OF THE DRAWINGS
The particular aspects of the invention will now be explained with reference to the embodiments described hereinafter and considered in connection with the accompanying drawings: Fig.l depicts a system for reading an information carrier,
Fig.2 depicts a cross-section of an information carrier according to the invention,
Fig.3 depicts a detailed view of said system for reading an information carrier,
Fig.4 illustrates by an example the principle of macro-cell scanning of an information carrier, Fig.5 depicts a first arrangement for scanning an information carrier,
Fig.6 depicts a second arrangement for scanning an information carrier,
Fig.7 depicts detailed elements of said second arrangement,
Fig.8 depicts a reading system according to the invention,
Fig.9 depicts a cross-section of a preferred information carrier according to the invention,
Fig.10 illustrates various apparatus and devices for reading an information carrier according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Fig.l depicts a three-dimensional view of a reading system according to the invention.
This system comprises an information carrier 101. The information carrier 101 comprises a data area DA intended to generate an output light beam representative of said data in response of an array of light spots 102. The data area DA comprises a set of square adjacent elementary data areas having size referred to as s and arranged as in a matrix. Data are coded on each elementary data area via the use of a material intended to take different transparency levels, for example two levels in using a material being transparent or non-transparent for coding a 2-states data, or more generally N transparency levels (for example N being an integer power of 2 for coding a 2log(N)-states data).
The information carrier 101 also comprises a diffractive structure DS intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure being placed beside said data area. The diffractive structure DS is made for example of a three-dimensional structure of different refractive indices. The diffractive structure DS is included in the information carrier during its manufacture. The characteristics of this diffractive structure are also known in particular by the reading apparatus so that it is able to perform a comparison between a diffractive pattern generated by the diffractive structure DS, and a reference diffractive pattern stored in said reading apparatus.
Fig.2 depicts a cross-section of an information carrier according to the invention. The data area DA must always be imaged on the detector when the light spots are focussed on said data area. To this end, the distance between the data area DA and the detector is such that the sharpness of the light beam outputted by the data area DA and detected by the detector is maximal. On the contrary, the diffractive structure DS itself must not be imaged on the detector when the light spots have the same focus plane as when they are applied to the data layer. Only the diffractive pattern must be imaged so that the encryption key plays fully its role. To this end, the data area DA and the diffractive structure DS are placed at a different depth in the information carrier 101. In other words, a depth difference Δe between these two elements is necessary.
The data area DA and the diffractive structure DS are included in a transparent layer TL made, for example, of plastic.
This system also comprises an optical element 104 for generating the array of light spots 102 which are intended to be applied to said elementary data areas.
The optical element 104 advantageously correspond to a two-dimensional array of apertures at the input of which the coherent input light beam 105 is applied. The apertures correspond for example to circular holes having a diameter of 1 μm or much smaller.
The array of light spots 102 is generated by the array of apertures in exploiting the Talbot effect which is a diffraction phenomenon working as follows. When a coherent light beam, such as the input light beam 105, is applied to an object having a periodic a diffractive structure (thus forming light emitters), such as the array of apertures, the diffracted lights recombines into identical images of the emitters at a plane located at a predictable distance zθ from the diffracting structure. This distance zθ is known as the Talbot distance. The Talbot distance zθ is given by the relation zθ = 2.n.d2 / λ, where d is the periodic spacing of the light emitters, λ is the wavelength of the input light beam, and n is the refractive index of the propagation space. More generally, re-imaging takes place at other distances z(m) spaced further from the emitters and which are a multiple of the Talbot distance z such that z(m) = 2.n.m.d2 / λ, where m is an integer. Such a re-imaging also takes place for Ta = 1A + an integer, but here the image is shifted over half a period. The re-imaging also takes place for m = 1A + an integer, and for m = 3A + an integer, but the image has a doubled frequency which means that the period of the light spots is halved with respect to that of the array of apertures.
Exploiting the Talbot effect allows generating an array of light spots of high quality at a relatively large distance from the array of apertures (a few hundreds of μm, expressed by z(m)), without the need of optical lenses. This allows inserting for example a cover layer between the array of aperture and the information carrier 101 for preventing the latter from contamination (e.g. dust, finger prints ...). Moreover, this facilitates the implementation and allows increasing in a cost-effective manner, compared to the use of an array of micro-lenses, the density of light spots which are applied to the information carrier.
Each light spot is intended to be successively applied to an elementary data area. According to the transparency state of said elementary data areas, the light spot is transmitted (not at all, partially or fully) to a CMOS or CCD detector 103 comprising pixels intended to convert the received light signal, so as to recover the data stores on said elementary data area.
Advantageously, one pixel of the detector is intended to detect a set of elementary data, said set of elementary data being arranged in a so-called macro-cell data, each elementary data area among this macro-cell data being successively read by a single light spot of said array of light spots 102. This way of reading data on the information carrier 101 is called macro-cell scanning in the following and will be described after.
Fig.3 depicts a partial cross-section and detailed view of the information carrier 101, and of the detector 103.
The detector 103 comprises pixels referred to as PX1-PX2-PX3, the number of pixels shown being limited for facilitating the understanding. In particular, pixel PXl is intended to detect data stored on the macro-cell data MCl of the information carrier, pixel PX2 is intended to detect data stored on the macro-cell data MC2, and pixel PX3 is intended to detect data stored on the macro-cell data MC3. Each macro-cell data comprises a set of elementary data.
For example, macro-cell data MCl comprises elementary data referred to as MCIa-MCIb-
MCIc-MCId. Fig.4 illustrates by an example the macro-cell scanning of the information carrier 101. For facilitating the understanding, only 2-states data are considered, similar explanations holding for an N-state coding. Data stored on the information carrier have two states indicated either by a black area (i.e. non-transparent) or white area (Le. transparent). For example, a black area corresponds to a "0" binary state while a white area corresponds to a "1" binary state.
When a pixel of the detector 103 is illuminated by an output light beam generated by the information carrier 101, the pixel is represented by a white area. In that case, the pixel delivers an electric output signal (not represented) having a first state. On the contrary, when a pixel of the detector 103 does not receive any output light beam from the information carrier, the pixel is represented by a cross-hatched area. In that case, the pixel delivers an electric output signal (not represented) having a second state.
In this example, each macro-cell data comprises four elementary data areas, and a single light spot is applied simultaneously to each set of data. The scanning of the information carrier 101 by the array of light spots 102 is performed for example from left to right, with an incremental lateral displacement which equals the period of the elementary data areas.
In position A, all the light spots are applied to non-transparent areas so that all pixels of the detector are in the second state.
In position B, after displacement of the light spots to the right, the light spot to the left side is applied to a transparent area so that the corresponding pixel is in the first state, while the two other light spots are applied to non-transparent areas so that the two corresponding pixels of the detector are in the second state.
In position C, after displacement of the light spots to the right, the light spot to the left side is applied to a non-transparent area so that the corresponding pixel is in the second state, while the two other light spots are applied to transparent areas so that the two corresponding pixels of the detector are in the first state.
In position D, after displacement of the light spots to the right, the central light spot is applied to a non-transparent area so that the corresponding pixel is in the second state, while the two other light spots are applied to transparent areas so that the two corresponding pixels of the detector are in the first state.
Elementary data which compose a macro-cell opposite a pixel of the detector are read successively by a single light spot. The scanning of the information carrier 101 is complete when the light spots have each been applied to all elementary data area of a macro-cell data facing a pixel of the detector. This implies a two-dimensional scanning of the information carrier.
To read the information carrier, a scanning of the information carrier by the array of light spots is done in a plane parallel to the information carrier. A scanning device provides translational movement of the light spots in the two directions x and y for scanning all the surface of the information carrier.
In a first solution depicted in Fig.5, the scanning device corresponds to an H-bridge.
The optical element generating the array of light spots (i.e. the array of micro-lenses or the array of apertures) is implemented in a first sledge 501 which is movable along the y axis compared to a second sledge 502. To this end, the first sledge 501 comprises joints 503-504-
505-506 in contact with guides 507-508. The second sledge 502 is movable along the x axis by means of joints 511-512-513-514 in contact with guides 509-510. The sledges 501 and 502 are translated by means of actuators (not represented), such as by step-by-step motors, magnetic or piezoelectric actuators acting as jacks.
In a second solution depicted in Fig.6, the scanning device is maintained in a frame 601. The elements used for suspending the frame 601 are depicted in a detailed three- dimensional view in Fig.7. These elements comprise: a first leaf spring 602, - a second leaf spring 603, a first piezoelectric element 604 providing the actuation of the scanning device 601 along the x axis, a second piezoelectric element 605 providing the actuation of the scanning device 601 along the y axis.
The second solution depicted in Fig.6 has less mechanical transmissions than the H- bridge solution depicted in Fig.5. The piezoelectric elements, in contact with the frame 601, are electrically controlled (not represented) so that a voltage variation results in a dimension change of the piezoelectric elements, leading to a displacement of the frame 601 along the x and/or the y axis.
The position Posl depicts the scanning device 601 in a first position, while the position Pos2 depicts the scanning device 601 in a second position after translation along the x axis. The flexibility of the leaf springs 602 and 603 is put in evidence. A similar configuration can be built with four piezoelectric elements, the two extra piezoelectric elements replacing the leaf springs 602 and 603. In that case, opposite pair of piezoelectric elements act together in one dimension in the same way as an antagonist pair of muscles.
The system according to the invention also comprises means for changing the relative position of said optical element 104 and said detector 103, and said diffractive structure DS, respectively, so as to align said optical element 104 and said detector 103 with said data area DA in view of detecting data on said detector, or to align said optical element and detector with said diffractive structure DS in view of detecting said cryptographic key on said detector.
To this end, the system may comprise, for example, actuation means (e.g. an actuator such as a linear servo motor, not shown) for displacing said optical element 104 and said detector 103 in a first position in front of said data area DA in view of detecting data on the detector (as illustrated by the top Fig.8), and in a second position in front of said diffractive structure DS in view of detecting said cryptographic key on the detector (as illustrated by the bottom Fig.8).
The cryptographic key may be analyzed by conventional processing means in charge of extracting optical characteristics in the diffractive pattern (e.g. by means of a signal processor executing code instructions reflecting the steps of an algorithm).
Fig.9 depicts an improved information carrier 901 according to the invention. The information carrier 901 differs from the information carrier depicted in Fig.2 in that it additionally comprises markers (Ml, M2) intended to be used for controlling the alignment between said array of light spots 102 and said diffractive structure DS. Markers may be made of non-transparent areas which are expected to generate a known pattern (e.g. a black dot) at a known position (e.g. on a specific pixel) on the detector when the information carrier is accurately positioned in the reading system. Accordingly, the reading system comprises detection means for detecting the markers
(Ml, M2) which are placed on the information carrier, and actuation means (e.g. piezoelectric actuators) for positioning said information carrier from said markers. Said detection means comprises the detector, and also analysis means for extracting said known pattern at a known position. Before detecting and analysing the diffractive patterns for recovering the cryptographic key, the information carrier is first accurately positioned in the reading system with the help of said markers. The expected reference diffractive pattern which characterizes the cryptographic key can thus be more easily detected.
In a preferred embodiment (not shown), the system comprises a Liquid Crystal (LC) layer placed at the input of the array of apertures 104. The LC layer aims at modifying the phase profile of the input light beam 105 according to various known and predetermined phase profiles (e.g. linear/quadratic phase profile, or a more complex phase profiles) set by the reading system. As a consequence, the optical characteristics of the array of light spots applied to the diffractive structures DS are modified.
If a pixelated LC layer is used, the various phase profiles are successively defined by addressing accordingly the matrix of LC elements. A first phase profile is defined and applied to the diffractive structure DS in view of detecting a first expected diffractive structure, a second phase profile is defined and applied to the diffractive structure DS in view of detecting a second expected diffractive structure, and so on. Instead the cryptographic key is derived from only one expected diffractive pattern, it is now derived from the matching between a plurality of couples (detected diffractive patterns, expected diffractive patterns). This reinforces the digital right management of the information carrier.
As illustrated in Fig.10, the system according to the invention may advantageously be implemented in a reading apparatus RA (e.g. home player apparatus ...), a portable device PD (e.g. portable digital assistant, portable computer, a game player unit...), or a mobile telephone MT. These apparatus and devices comprise an opening (OP) intended to receive an information carrier 1001 as depicted by Fig.2 and/or Fig.9, and a system as depicted by Fig.l and Fig.8 in view of recovering data and the cryptographic key stored on said information carrier.
The verb "comprise" does not exclude the presence of other elements than those listed in the claims.

Claims

1. An information carrier (101) intended to store data, said information carrier comprising: a data area (DA) intended to generate an output light beam representative of said data in response of an array of light spots, a diffractive structure (DS) intended to generate at least one diffractive pattern representative of a cryptographic key in response of said array of light spots, said diffractive structure (DS) being placed beside said data area (DA) and at a different depth in said information carrier (101).
2. An information carrier as claimed in claim 1, further comprising markers (Ml, M2) intended to be used for controlling the alignment between said array of light spots and said diffractive structure.
3. A system for reading an information carrier comprising a data area (DA) and a diffractive structure (DS) representative of a cryptographic key, said system comprising: an optical element (104) for generating an array of light spots (102) intended to be applied to said information carrier, a detector (103) for detecting the output light beam generated by said information carrier in response of said array of light spots (102), - means for changing the relative position of said optical element (104) and said detector
(103), with respect to said diffractive structure (DS), so as to align said optical element (104) and detector (103) with said data area (DA) in view of detecting data on said detector (103), or to align said optical element (104) and detector (103) with said diffractive structure (DS) in view of detecting said cryptographic key on said detector (103).
4. A system as claimed in claim 3, further comprising:
- detection means for detecting markers placed on said information carrier,
- actuation means for positioning said information carrier from said markers.
5. A system as claimed in claim 3 or 4, further comprising a liquid crystal layer (LC) placed at the input of said optical element for modifying the optical characteristics of the array of light spots applied to said diffractive structures (DS).
6. A portable device comprising a system as claimed in claim 3, 4 or 5.
7. A mobile telephone comprising a system as claimed in claim 3, 4 or 5.
8. A game player unit comprising a system as claimed in claim 3, 4 or 5.
PCT/IB2005/052468 2004-07-29 2005-07-22 Information carrier with copy protection, system for reading such an information carrier WO2006013528A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP04300492.8 2004-07-29
EP04300492 2004-07-29

Publications (1)

Publication Number Publication Date
WO2006013528A1 true WO2006013528A1 (en) 2006-02-09

Family

ID=35431296

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2005/052468 WO2006013528A1 (en) 2004-07-29 2005-07-22 Information carrier with copy protection, system for reading such an information carrier

Country Status (2)

Country Link
TW (1) TW200617934A (en)
WO (1) WO2006013528A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8324562B2 (en) 2007-07-20 2012-12-04 Koninklijke Philips Electronics N.V. Fiber scanning system having a magnet attached to the fiber at a position before or after an electrical coil with improved tip positioning

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5587984A (en) * 1994-09-13 1996-12-24 Sony Corporation Hologram printed on optical recording medium for copy protection
EP0980070A2 (en) * 1998-08-10 2000-02-16 Electrowatt Technology Innovation AG Diffractive security device on compact discs
WO2002011050A2 (en) * 2000-07-31 2002-02-07 Trid Store Ip Llc Method for data reading/writing using an optical carrier with pattern information pits
US20020186919A1 (en) * 2001-06-08 2002-12-12 Hrl Laboratories, Llc Electro-optical programmable true-time delay generator
US20030235135A1 (en) * 2002-06-24 2003-12-25 Yin-Chun Huang Data reading apparatus and operating method thereof
WO2005048256A2 (en) * 2003-11-14 2005-05-26 Koninklijke Philips Electronics N.V. A data carrier having security mark and apparatus for handling such data carrier.

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5587984A (en) * 1994-09-13 1996-12-24 Sony Corporation Hologram printed on optical recording medium for copy protection
EP0980070A2 (en) * 1998-08-10 2000-02-16 Electrowatt Technology Innovation AG Diffractive security device on compact discs
WO2002011050A2 (en) * 2000-07-31 2002-02-07 Trid Store Ip Llc Method for data reading/writing using an optical carrier with pattern information pits
US20020186919A1 (en) * 2001-06-08 2002-12-12 Hrl Laboratories, Llc Electro-optical programmable true-time delay generator
US20030235135A1 (en) * 2002-06-24 2003-12-25 Yin-Chun Huang Data reading apparatus and operating method thereof
WO2005048256A2 (en) * 2003-11-14 2005-05-26 Koninklijke Philips Electronics N.V. A data carrier having security mark and apparatus for handling such data carrier.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
RAVIKANTH P S: "Physical One-way Functions", March 2001, THESIS AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY, PAGE(S) 1-154, XP002251679 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8324562B2 (en) 2007-07-20 2012-12-04 Koninklijke Philips Electronics N.V. Fiber scanning system having a magnet attached to the fiber at a position before or after an electrical coil with improved tip positioning

Also Published As

Publication number Publication date
TW200617934A (en) 2006-06-01

Similar Documents

Publication Publication Date Title
EP1771860B1 (en) Information carrier, system and apparatus for reading such an information carrier
JP2004177958A (en) Method for executing holography record/readout based on page
EP1771849B1 (en) Information carrier, system for reading said information carrier, method of manufacturing said information carrier
KR20080056014A (en) Method and system for scanning an information carrier via one-dimensional scanning
US7738736B2 (en) Methods and systems for holographic data recovery
JP2007156801A (en) Optical information recording method and reproduction method
JP2007506209A (en) Information carrier and system for reading data stored in the information carrier
CN100557688C (en) Optical information detecting method and optical information detector
TW200521604A (en) System for shifting at least one light spot
WO2006013528A1 (en) Information carrier with copy protection, system for reading such an information carrier
EP2118895B1 (en) Method of reading a fourier hologram recorded on a holographic storage medium and a holographic storage system
WO2006013519A1 (en) Method of storing data in an information carrier, system for reading such an information carrier.
KR100601283B1 (en) Apparatus and method for detecting align mark for over-sampling in hologram data reproducing system
KR100600300B1 (en) Holographic digital data system and method for detecting recording image's unmatching therefor
EP1807832B1 (en) Optical device for scanning an information carrier
JP2008524762A (en) Data encoding method on information carrier and system for reading the information carrier
KR100601256B1 (en) Method and device for reading of the holographic digital data system
KR20080068118A (en) Method and system for adjusting the pitch of light spots used to read an information carrier
KR20090057123A (en) Optical holographic device and method with alignment means
KR100682259B1 (en) Method for optimally detecting frame on ccd image in a hdds
KR20080017964A (en) Method and apparatus for recording/replaying data
JP2005018940A (en) Recording and reproducing device

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU LV MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase