WO2010113078A1

WO2010113078A1 - Information carrier, reproduction apparatus and manufacturing apparatus

Info

Publication number: WO2010113078A1
Application number: PCT/IB2010/051277
Authority: WO
Inventors: Jacobus M. Den Hollander; Henricus F. P. M. Van Doveren
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2009-03-31
Filing date: 2010-03-24
Publication date: 2010-10-07
Also published as: TW201040787A

Abstract

The present invention relates to an information carrier, a reproduction apparatus and method and a manufacturing apparatus and method. To provide a secure protection of data on the information carrier and also to provide safety against the save-and- restore attack an information carrier is proposed having stored thereon a payload data stream (E) comprising payload data (C) stored in blocks according to a first format allowing reproduction by a reproduction apparatus adapted for reproduction of data according to the first format, and confusion data (D) stored in between the blocks of payload data (C), wherein the confusion data (D) do not contain actual payload data (C) and are stored according to a second format, that does not allow the reproduction apparatus to distinguish it from payload data (C) stored according to the first format and that does not allow a recording apparatus adapted for recording of data according to the first format to copy the confusion data (D) and record them on another information carrier.

Description

Information carrier, reproduction apparatus and manufacturing apparatus

FIELD OF THE INVENTION

The present invention relates to an information carrier, to a reproduction apparatus and method for reproducing payload data from an information carrier and to a manufacturing apparatus and method for manufacturing an information carrier.

BACKGROUND OF THE INVENTION

There is an increasing need for protection of usage rights by means of Digital Rights Management (DRM). As is described in WO 2006/064412 Al, DRM can be Network- centric, Card-centric, Device-centric or Media-centric. In the latter case, the digital rights are solely stored on the media.

A typical attack on such a Media-centric DRM solution is the so called 'save- and-restore' attack where an image of the disc is created which contains all channel bits stored on the original information carrier (also hereinafter referred to as storage medium), such as an optical disc. The image is a one-to-one copy of the information carrier without further interpretation of the bits. This image is written on a blank information carrier in order to produce a copy.

One way to resolve this hack is the method described in WO 02/015184 Al where it is proposed to use a Hidden Channel (HC). The HC is a side channel (SC) on the storage medium, which is used to store information in, necessary for the DRM. The user cannot write a SC, therefore the DRM information is lost in a save-and-restore attack.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an information carrier, a reproduction apparatus and method as well as a manufacturing apparatus and method which allow a secure protection of data on the information carrier and by which also provide safety against the save-and-restore attack.

In a first aspect of the present invention an information carrier is presented having stored thereon a payload data stream comprising: - payload data stored in blocks according to a first format allowing reproduction by a reproduction apparatus adapted for reproduction of data according to said first format and

- confusion data stored in between said blocks of payload data, wherein said confusion data do not contain actual payload data and are stored according to a second format, that does not allow said reproduction apparatus to distinguish it from payload data stored according to said first format and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data and record them on another information carrier.

In a further aspect of the present invention a reproduction apparatus is presented for reproducing from such an information carrier having stored thereon a payload data stream, said apparatus comprising:

- reading means for reading said payload data stream from said information carrier and

- de-interleaving means for reproducing said payload data stored in blocks and ignoring the confusion data stored in between said blocks of payload data. In still a further aspect of the present invention a manufacturing apparatus is presented for manufacturing an information carrier according to the present invention, said apparatus comprising:

- interleaving means for interleaving payload data and confusion data into a payload data stream in which the payload data are arranged in blocks and the confusion data are arranged in between said blocks,

- recording means for recording said data stream onto said information carrier, wherein the payload data are stored to a first format allowing reproduction by a reproduction apparatus adapted for reproduction of data according to said first format and said confusion data do not contain actual payload data and are stored according to a second format, that does not allow said reproduction apparatus to distinguish it from payload data stored according to said first format and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data and record them on another information carrier.

According to further aspects of the present invention, a corresponding reproduction method and a corresponding manufacturing method are presented.

Preferred embodiments of the invention are defined in the dependent claims. It shall be understood that all the claimed methods and devices have similar and/or identical preferred embodiments as the claimed information carrier and as defined in the dependent claims. The present invention is based on the idea to create a hidden channel (HC) by hiding the copy protection data in an area containing confusion data (or patterns). A confusion pattern is a pattern that appears to contain information but actually does not. The confusion pattern is significantly different from traditional recording patterns, and at the same time it is difficult to discriminate from the area that does contain information. A boundary condition for the confusion pattern is that it must be written along a track and that the drive (i.e. the recording apparatus and/or reproduction apparatus) must be able to follow this track.

According to a preferred embodiment said second format is adapted such that it does not allow said reproduction apparatus and said recording apparatus to reproduce said confusion data. In other words, reproduction and recording apparatus which are adapted for reproducing/recording of data according to said first format are generally not able to reproduce said confusion data. Such apparatus would need to be severely modified in order to enable the reproduction of said confusion data which makes it very difficult and cost- intensive for developers/producers of such apparatus to implement such a functionality.

Moreover, this functionality would enable a simpler detection of infringement of this kind of rights protection since generally there will be no other reason to implement this functionality apart from the reason to circumvent this copyright protection.

According to another preferred embodiment the distance between the blocks in which said confusion data is stored is fixed and predetermined. In this case, the compliant device then only needs to be informed of this distance information to enable it to read out the actual payload data and ignore the confusion data. This distance information can, for instance, be provided via an external link, e.g. it can be provided by the content owner or other certified authority, or the distance information can be stored on the device itself. However, further possibilities exist as well.

According to an alternative embodiment the distance between said blocks is variable. In this case the distance can be made dependent on some other data related uniquely to the reproduction apparatus and/or recording apparatus. Hence, only particular apparatus are then able to determine the correct distance information whereas other (non-compliant or illegal) apparatus are not able to determine the correct distance information, for instance because their apparatus identification does not lead, e.g. via a fixed algorithm, to the correct distance information. This embodiment does provide the ability and flexibility to certify certain devices but exclude other devices from the access to the information carrier. Preferably, said payload information contains copy protection data or digital rights management data. However, generally the information can be applied for protection of other kind of information or data as well.

A preferred embodiment of the reproduction apparatus according to the present invention comprises a distance determination means for determining the distance between the blocks of payload data, wherein said reading means is adapted to use said determined distance to read and reproduce only the payload data stored in those blocks and to ignore said confusion data. Preferably, said distance determination means is adapted for determining the distance from a distance information stored on the information carrier. However, the distance information can also be stored in the reproduction apparatus itself, if the reproduction apparatus is a compliant device, or can be provided from an external device or authority as mentioned above.

According to another embodiment of the reproduction apparatus said distance determination means is adapted for determining the distance by use of a multiplication factor indicating the distance as the product of said multiplication factor times a unit length, in particular the product of said multiplication factor times the channel bit length or wobble period. In particular, the frequency which determines the bit clock for the hidden channel (i.e. the channel storing the payload data and hidden by use of the confusion data) is multiplied. The advantage is that a higher bit clock is obtained which allows for a higher information density.

Preferably said distance determination means comprises a phase locked loop (PLL) to provide timing information. The PLL will provide this timing information to the reproduction apparatus, so that the reproduction apparatus can, based thereon, determine the beginning and end of a block containing actual payload data. The bit clock frequency is thus preferably equal to the product of the timing information frequency and the multiplication factor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the following drawings

Fig. 1 shows a block diagram of an embodiment of a manufacturing apparatus according to the present invention,

Fig. 2 shows a schematic diagram illustrating a channel data stream according to an embodiment of the present invention, Fig. 3 shows a schematic diagram illustrating the interleaving of payload data and confusion data according to an embodiment of the present invention,

Fig. 4 shows a block diagram of an embodiment of a reproduction apparatus according to the present invention, Fig. 5 shows a schematic diagram illustrating how timing information is hidden in the confusion data according to an embodiment of the present invention,

Fig. 6 shows a schematic diagram illustrating how the blocks storing payload data can be found according to an embodiment of the present invention,

Figs. 7 A, 7B show a further embodiment how payload data and confusion data can be interleaved, and

Fig. 8 shows a schematic diagram illustrating how different groups of payload data can be interleaved with confusion data.

DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows a block diagram of an embodiment of a manufacturing apparatus

10 for manufacturing an information carrier 20 according to the present invention. The manufacturing apparatus 10 comprises an interleaving unit 12 which receives payload data C, such as digital rights management data or copy protection data (generally, the payload data C could also be other data that shall be securely protected, such as audio, video or software data), a key K and confusion data D. The payload data C are generally provided from a content owner of the content data F (e.g. audio, video or software data) that shall be stored on the information carrier 20 and that shall, for instance, be protected by the payload data C against illegal copying or whose recording or reproduction shall be restricted by said payload data C. The content owner is, for instance, a music or software company. The confusion data D are generally generated and provided by a confusion data generator 14 which is generally part of the manufacturing apparatus 10. The key K can be provided by an external instance 18, such as the content owner, any other certified authority or the drive vendor. The key K determines how the payload data C is interleaved with the confusion data D by the interleaving unit 12. The interleaving unit 12 interleaves the payload data C and the confusion data

D by use of the key K into a payload data stream E in which the payload data C are arranged in blocks and the confusion data D are arranged in between said blocks of payload data C. This payload data stream E is then provided to a recording unit 16. The recording unit 16 also receives the content data F which is the actual payload of the information such as audio, video or software data. The recording unit 16 generates the channel data stream G by interleaving the content data F and the data of the payload data stream E using a switch for switching between data streams E and F under control of a control signal S. The channel data stream G outputted from the recording unit 16, which is schematically illustrated in Fig. 2, is recorded onto the information carrier 20.

The information carrier 20 is preferably an optical disc, such as a CD, DVD or BD, and also the general layout and function of the interleaving unit 12 and the recording unit 16 are generally known in the art and are thus not explained in more detail here.

According to the present invention payload data C (i.e. the copy protection data or the digital rights management information) are stored according to a first format allowing reproduction by a reproduction apparatus adapted for the reproduction of data according to said first format. This first format is preferably a standardized format, such as the CD audio standard or the DVD-ROM standard, which formatting of the raw payload has been done in other elements of the manufacturing apparatus 10 (not shown) or which has been done before the payload data C are actually provided to the manufacturing apparatus, for instance in an external data processing device including generally known elements such as an encoder (e.g. an ECC encoder) and a modulator (e.g. a EFM modulator).

The content data F are preferably also stored in the first format, preferably a standard format, so that reproduction is possible with a standardized reproduction apparatus. However, it is also possible that the content data F are stored in a different format, e.g. in a format having a lower bit error rate. It is generally not important if the same formats are used for storing the content data F and the payload data C, and which formats are used for storing these data.

Further, the storage of content data F interleaved with the data of the payload data stream E is not an essential feature of the present invention. It is also possible that only the payload data stream E is stored in the channel data stream G and on the information carrier, either completely separate from (i.e. not interleaved with) the content data F, or without any content data F at all.

According to the present invention the confusion data D do not contain actual payload data and are stored on the information carrier 20 according to a second format, that does not allow said reproduction apparatus (which is adapted for reproduction of data according to said first format) to distinguish it from payload data C and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data and record them on another information carrier. In other words, only a compliant reproduction apparatus which knows how to distinguish between payload data C and confusion data D, e.g. which exactly knows the positions of the payload data C in the payload data stream E, can correctly reproduce the payload data C. Further, and more important, a recording apparatus is generally not able to copy the payload data C, which is particularly important in case where copy protection data or digital rights management data shall be protected against copying to avoid that hackers can illegally make (an unlimited number of) copies of protected content data or that the content is replayed without restriction despite digital rights management data containing restrictions regarding the reproduction (e.g. country restrictions, age restrictions, restrictions regarding the number of replays, time restrictions, ...).

Fig. 3 shows a payload data stream E showing the blocks Cl to C4 of payload data C interleaved with blocks Dl to D4 of confusion data D. Between the blocks Cl to C4 of payload data C a constant or a variable interleaving distance d can be used. In the example shown in Fig. 3 the distances dl to d5 are indicated, wherein the distance d indicates the start or end of a block containing payload data C. The payload data stream E can thus be regarded as a kind of hidden channel hiding the payload data C with interleaved confusion data D.

It shall be noted here that a variable interleaving distance d can be specified depending on the drive/vendor ID, i.e. a unique identifier of the drive or the vendor of the drive. It shall further be noted that interleaving also enhances the robustness of the readout of the data since burst errors (scratches, fingerprints) only affect a small part of the data.

Fig. 4 shows a block diagram of an embodiment of a reproduction apparatus 30 according to the present invention. The reproduction apparatus 30 comprises a reading unit 32 for reading the channel data stream G from the information carrier 20 and for de- interleaving the content data F and the payload data stream E therefrom. The content data F can then be further processed, e.g. decoded, demodulated and reproduced, in the usual and known manner as required. Selection between the content data F and the data of the payload data stream E is done based on a control signal S.

The payload data stream E is then provided to a de- interleaving unit 36 for de- interleaving, for reproducing the payload data C and for ignoring the confusion data D stored in between said blocks of payload data C. Said de-interleaving unit 36 is generally interrelated to the interleaving unit 16 of the manufacturing apparatus 10.

For said de-interleaving and reproduction of said payload data the de- interleaving unit 36 requires some information on how and/or where to find said payload data C in said payload data stream E. Preferably, the distance information d is provided to the de- interleaving unit 36 informing the de-interleaving unit 36 on the distances between the blocks of payload data and thus indicating the beginning and end of those blocks of payload data C which need to be reproduced so that the blocks interleaved therebetween can be ignored as they are interpreted to contain confusion data D only. The distance information d can be stored (directly, or indirectly as distance- related information) in the reproduction apparatus 30 or it can be read from the information carrier 20 where it can be, for instance, stored at some hidden location which is only known to a compliant reproduction apparatus. In a further embodiment, as explicitly shown in Fig. 4, a distance determination unit 34 is provided for determining the distance between the blocks of payload data C based, for instance, on some distance information stored on the information carrier or provided from an external instance 18, such as the content owner or any other certified authority.

In an embodiment, for instance, said distance determination unit 34 is adapted for determining the distance by use of a multiplication factor indicating the distance as the product of said multiplication factor times a unit length, which unit length can be the channel bit length or a wobble period. Of course, other unit lengths that are available or appropriate can be used as well.

As mentioned, the distance d can be expressed in wobble periods, if a wobble (which is generally known in the art of optical recording media) is added to the track containing the hidden channel. Another way of expressing distance d can be by using an arbitrary unit length (e.g. equivalent of the channel bit length), which is given by the timing information embedded in the confusion patterns. The timing information can be retrieved by means of a PLL. Timing information can be hidden in the confusion patterns by placing only a subset of the edges (rising/falling) in the confusion pattern on a grid. This is illustrated by the diagram shown in Fig. 5. A PLL is fed with the zero crossings indicated by f(n) (gating) where f(n) is a scalar pointing to the zero crossing to be used. Hence the PLL will lock to the f(n)-th edge after the last used edge (f(2..6) = 3 4 4 1 4). The information to which edge the PLL shall lock is generally embedded in key signal K, i.e. the secret key which is, for instance, stored in the reproduction device 30, or provided by the third party 18 via a link. It should be noted here that f(n) can be made drive/vendor specific such that different drives use different timings.

The advantage of this solution compared to existing solutions is that the confusion pattern will call the attention of a pirate who attempts to make an illegal copy of the information carrier. By making these patterns difficult to reproduce, it can become economically unattractive for the pirate to attempt to duplicate the information carrier. Further, there is a large freedom to change the confusion patterns without compromising the principle according to which the hidden channel is made.

It is free to the designer of the system to use an appropriate modulation code for the payload data in the blocks Cl to C4 (cf. Fig. 3). An example could be to use a spread spectrum type of modulation. These are known for their robustness and are hard to detect without knowledge of the demodulation sequence the (de-)modulation sequence could be based on the drive/vendor ID). Alternatively, a straightforward repetition code, perhaps combined with a simple Hamming-code error correction, can be used. Preferably, the payload data C to be protected, e.g. the data bit (copy protection bit), is sufficiently repeated to guarantee a Bit Error Rate, which is sufficiently low (typically in the range of 10^~12).

Fig. 6 shows a schematic diagram illustrating how the blocks storing payload data can be found according to the present invention. As can be derived therefrom the blocks Cl and C2 of payload data are interleaved in blocks Dl to D3 of confusion data. By use of variable interleaving and timing information f(l), f(2), f(3) the blocks Cl, C2 can be found. The selection of the edges to be used for finding the blocks Cl, C2, ... of payload data C is based on the key K, i.e. essentially a gating method is applied.

Preferably, the frequency which determines the bit clock for the payload data stream E is multiplied. The advantage is that a higher bit clock is obtained which allows for a higher information density. Imagine the following case. The distance between the pieces of timing information (denoted as f(l), f(2, ... in Fig. 6) are 1 ms apart. This corresponds to a frequency of 1 kHz. In order to make a bit-clock of 10 kHz, a multiplication of a factor 10 is used in the PLL. This multiplication factor could be secret (e.g. a key), standardized, provided via an external link or provided by the payload owner as explained above. Next, two particular embodiments, according to which data is stored on an optical disc according to a certain standard (generally referred to as the channel code), shall be explained. All standardized channel codes for optical storage have in common that they are binary level and use discrete runlengths. In one embodiment this property is exploited by using a confusion pattern which uses more than two levels. An example of this is shown in Fig. 6 where four levels are used. When the payload data C are reproduced, the multi-level signal T, whose reflection R is shown over time t, is translated into a binary signal by comparing it with a slicer level SL. If the signal level exceeds the sheer level SL it gets a first binary level (e.g. 1), in all other cases it gets the other binary value (e.g. zero). Thus, it is not possible for a reproduction apparatus to distinguish the confusion data D from payload data C stored according to said first format (i.e. the standardized format using only two (binary) levels). Further, it is also not possible for a recording apparatus adapted for recording of data according to said first format (using only a binary level) to copy said confusion data and record them on another information carrier, i.e. such a recording device cannot apply multi-level recording.

According to a second embodiment applicable for optical storage media the property is exploited that all channel codes used for optical storage use discrete runlengths. In Figs.7A, 7B, two waveforms are shown. Fig. 7A one shows a signal Tl having typical waveform representing an optical storage standardized channel code. The transitions are clearly aligned on a grid resulting in discrete runlengths, and there is a limit on the minimum and maximum runlength (not shown in this figure). The latter is generally known and referred to as the d,k constraint.

The second signal T2 shown in Fig. 7B shows what it would look like if the transitions are put off the grid. Consequently the runlengths are not discrete making it significantly different. It should, however, be noted that due to noise, the transitions are never perfectly on the grid, but the standard variation is typically very small. For illustrative purposes of this embodiment it should be clear that the transitions are intentionally put off grid. Further, different limitations could be set on the minimum and/or maximum runlength. Thus, also according to this embodiment, it is not possible for a reproduction apparatus to distinguish the confusion data from payload data stored according to said first format (i.e. the standardized format where the transitions are aligned along the grid). Further, it is also not possible for a recording apparatus adapted for recording of data according to said first format to copy said confusion data and record them on another information carrier, i.e. such a recording device cannot intentionally put the transitions off grid.

It should be noted here that for applications other than optical storage different examples may apply.

According to a further embodiment different messages could be interleaved in the channel. The message that the reproducing device reads could depend on its ID/rights. For instance, if a disc which is distributed in the USA shall be replayed in a

European player, it can not be played back because the European player reads a different code from the confusion pattern because of its different (European) ID. This is illustrated in Fig. 8 showing a channel stream E according to this embodiment. The blocks Dl to D5 of confusion data here interleave blocks CAl to C A3 that contain payload data for USA players and blocks CBl to CB3 that contain payload data for European players. The player will then select the blocks with payload data based on its ID.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. Information carrier (20) having stored thereon a payload data stream (E) comprising:

- payload data (C) stored in blocks according to a first format allowing reproduction by a reproduction apparatus (30) adapted for reproduction of data according to said first format and

- confusion data (D) stored in between said blocks of payload data (C), wherein said confusion data (D) do not contain actual payload data (C) and are stored according to a second format, that does not allow said reproduction apparatus (30) to distinguish it from payload data (C) stored according to said first format and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data (D) and record them on another information carrier (20).

2. Information carrier (20) as claimed in claim 1, wherein said second format is adapted such that it does not allow said reproduction apparatus (30) and said recording apparatus to reproduce said confusion data (D).

3. Information carrier (20) as claimed in claim 1, wherein a distance (d) between said blocks is fixed and predetermined.

4. Information carrier (20) as claimed in claim 1, wherein a distance (d) between said blocks is variable.

5. Information carrier (20) as claimed in claim 3 or 4, wherein a distance information is stored on the information carrier (20) allowing a reproduction apparatus to determine the distance (d) between said blocks to enable said reproduction apparatus to ignore said confusion data (D) and to access only said payload data (C) for reproduction.

6. Information carrier (20) as claimed in claim 1, wherein said payload data (C) contains copy protection data or digital rights management data.

7. Reproduction apparatus (30) for reproducing payload data (C) from an information carrier (20) as claimed in claim 1 having stored thereon a payload data stream (E), said apparatus comprising:

- a reading unit (32) for reading said payload data stream (E) from said information carrier (20), and - a de-interleaving unit (36) for reproducing said payload data (C) stored in blocks and ignoring the confusion data (D) stored in between said blocks of payload data (C).

8. Reproduction apparatus as claimed in claim 7, further comprising a distance determination unit (34) for determining a distance between the blocks of payload data (C), wherein said de-interleaving unit (36) is adapted to use said distance to read and reproduce only the payload data (C) stored in said blocks and to ignore said confusion data (D).

9. Reproduction apparatus as claimed in claim 8, wherein said distance determination unit (34) is adapted for determining the distance from a distance information stored on the information carrier (20).

10. Reproduction apparatus as claimed in claim 8, wherein said distance determination unit (34) is adapted for determining the distance by use of a multiplication factor indicating the distance as the product of said multiplication factor times a unit length, in particular the product of said multiplication factor times a channel bit length or wobble period.

11. Reproduction apparatus as claimed in claim 8, wherein said distance determination unit (34) comprises a phase locked loop for providing timing information.

12. Reproduction method for reproducing payload data from an information carrier (20) as claimed in claim 1 having stored thereon a payload data stream (E), said method comprising the step of:

- reading said payload data stream (E) from said information carrier (20), and

- reproducing said payload data (C) stored in blocks and ignoring the confusion data (D) stored in between said blocks of payload data (C).

13. Manufacturing apparatus (10) for manufacturing an information carrier (20) as claimed in claim 1, said apparatus comprising:

- an interleaving unit (12) for interleaving payload data (C) and confusion data (D) into a payload data stream (E) in which the payload data (C) are arranged in blocks and the confusion data (D) are arranged in between said blocks,

- a recording unit (16) for recording said payload data stream (E) onto said information carrier (20), wherein the payload data (C) are stored according to a first format allowing reproduction by a reproduction apparatus adapted for reproduction of data according to said first format and said confusion data (D) do not contain actual payload data (C) and are stored according to a second format, that does not allow said reproduction apparatus to distinguish it from payload data (C) stored according to said first format and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data (D) and record them on another information carrier (20).

14. Manufacturing method for manufacturing an information carrier (20) as claimed in claim 1 , said method comprising the steps of:

- interleaving payload data (C) and confusion data (D) into a payload data stream (E) in which the payload data (C) are arranged in blocks and the confusion data (D) are arranged in between said blocks,

- recording said data stream (E) onto said information carrier (20), wherein the payload data (C) are stored to a first format allowing reproduction by a reproduction apparatus adapted for reproduction of data according to said first format and said confusion data (D) do not contain actual payload data (C) and are stored according to a second format, that does not allow said reproduction apparatus to distinguish it from payload data (C) stored according to said first format and that does not allow a recording apparatus adapted for recording of data according to said first format to copy said confusion data (D) and record them on another information carrier (20).