WO2004055651A1

WO2004055651A1 - A simple digital right management language

Info

Publication number: WO2004055651A1
Application number: PCT/IB2003/005230
Authority: WO
Inventors: Willem Jonker; Robert P. Koster
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2002-12-17
Filing date: 2003-11-18
Publication date: 2004-07-01
Also published as: AU2003280073A1

Abstract

The present invention relates to a server (11), a device (14), a system and methods for simplified management of digital rights. The invention is based on the idea that rights are expressed in a DRM language containing a limited number of rights expressions focusing on the core DRM mechanisms. Read DRM elements are mapped onto a number of binary digits. The number of bits is provided such that it enables control of a device receiving the number of bits. The number of bits will be executed like an instruction word. By employing this concept, CE devices having limited processing power, such as for example CD players (14), portable displaying devices and mobile phones, are advantageously relieved from the managing and processing of a complex DRM language and need only process the number of bits presented to them.

Description

A SIMPLE DIGITAL RIGHT MANAGEMENT LANGUAGE

The present invention relates to a server, a device, a system and methods for simplified management of digital rights.

In today's society, the rapid spread of digital information has given birth to the concept of digital rights management (DRM). This concept is used to protect the rights of a creator of the digital information as well as the rights of an information provider distributing the information. This concept is applicable to information distributed via any type of media, such as the Internet, a CD, a DVD or the like. It is also applicable to any type of information, for example audio, video, text etc.

DRM systems incorporate more and more different business models which requires that the DRM system is sufficiently flexible to handle many different types of rights. To facilitate the management of the digital rights for the participants in the systems, rights are expressed using digital rights management languages. These languages are also called rights expression languages and include, for example, ODRL (Open Digital Rights Language) and XrML (Extensible Rights Markup Language). DRM languages usually conform to a standard language notation. ODRL and XrML both allow the rights to be expressed using XML (Extensible Markup Language) notation.

A description of XrML is given in "XrML Technical Overview", version 1.0, published March 8, 2002 by ContentGuard™. The document describes the XML-based DRM language XrML, which language thus is used to specify digital rights and conditions to control the access to digital information and services. According to this document, anyone owning or distributing digital resources can identify the parties allowed to use those resources, the rights available to those parties, and the terms and conditions under which those rights may be exercised using XrML. XrML is an advanced DRM language, and the number of possible rights expressions is rather extensive.

A problem with XrML, as well as with ODRL, is that these DRM languages are very complex in terms of the type of rights that can be expressed, and as a result thereof are difficult to manage and process. These consequences of the language complexity make the languages unsuitable for consumer electronics (CE) devices, in particular small devices with limited processing power, such as portable CD players and the like.

An object of the present invention is to solve the problem of how to simplify management and use of DRM languages. This object is achieved by a method at a server for simplified management of digital rights according to claim 1, a server for simplified management of digital rights according to claim 2, a method at a device for simplified management of digital rights according to claim 3, a device for simplified management of digital rights according to claim 5, a method at a system for simplified management of digital rights according to claim 7 and a system for simplified management of digital rights according to claim 9.

According to a first aspect of the invention, a method is provided in which DRM language elements are read. From a storage area containing the read DRM language elements and sets of binary digits associated with the elements, the sets of binary digits corresponding to each read DRM element is derived. The read DRM elements are mapped onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element. The set of binary digits is provided such that it enables control of a device receiving the number of binary digits.

According to a second aspect of the invention, a server is provided comprising processing means and storing means. The storing means is arranged to store DRM language elements and sets of binary digits associated with the elements. The processing means is arranged to read DRM language elements and to derive the set of binary digits corresponding to each read DRM element from the storing means. The processing means is further arranged to map the read DRM elements onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element. The number of binary digits is provided such that it enables control of a device receiving the number of binary digits.

According to a third aspect of the invention, a method is provided in which binary digits representing DRM language elements are received. A device is controlled in accordance with the received binary digits representing DRM language elements. According to a fourth aspect of the invention, a device is provided comprising receiving means arranged to receive binary digits representing DRM language elements. Moreover, the device comprises processing means arranged to control the device in accordance with the received binary digits representing DRM language elements. According to a fifth aspect of the invention, a method is provided in which DRM language elements are read at a server. From a storage area at the server, which area contains the read DRM language elements and sets of binary digits associated with the elements, the set of binary digits corresponding to each read DRM element is derived. At the server, the read DRM elements are mapped onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element. The number of binary digits is provided such that it enables control of a device receiving the number of binary digits. The number of binary digits is distributed from the server to a device. The number of binary digits representing DRM language elements is received at the device and the device is controlled in accordance with the received number of digits. The DRM language elements represented by the received number of binary digits are thereby derived.

According to a sixth aspect of the invention, a system is provided comprising a server including a first processing means, a first storing means and transmission means and at least one device including a second processing means and receiving means. The first storing means is arranged to store DRM language elements and sets of binary digits associated with the elements. The first processing means is arranged to read DRM language elements, to derive the set of binary digits corresponding to each read DRM element from said first storing means and to map each read DRM element onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element. The set of binary digits is provided such that it enables control of the device receiving the number of binary digits. The transmission means is arranged to distribute the number of binary digits to the device. The receiving means is arranged to receive the number of binary digits representing DRM language elements and the second processing means is arranged to control the device in accordance with the received number of binary digits representing DRM language elements.

The invention is based on the idea that rights are expressed in a DRM language containing a limited number of rights expressions focusing on the core DRM mechanisms. Preferably, the language used conforms to XML, given the broad spread of the XML technology. The limitation of the number of rights expressions can be performed by utilizing a subset of the rights expressions given in an existing language such as XrML or ODRL. It is also possible to introduce a new DRM language supporting a fewer number of rights expressions than the existing languages. An example of a less extensive DRM language will be described later. The DRM language rights expressions, i.e. the DRM language elements, are read by a processing means such as a CPU. A storage area containing read DRM language elements and sets of binary digits associated with the element is employed. The set of binary digits corresponding to each read DRM element is derived from the storage area. The read DRM elements are then mapped onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read element. The number of binary digits (hereinafter referred to as "the number of bits") is provided such that it enables control of a device receiving the number of digits.

The number of bits will, when the mapping is completed, correspond to a rights expression composed of the read DRM language elements. The reading of the DRM language elements, the deriving of the set of binary digits corresponding to each read element and the creating of the number of bits by means of the mapping is preferably performed at a server or the like. The number of bits, i.e. the representation of the digital rights, is then distributed together with some digital information, such as an audio file. The number of bits can also be distributed separate from the digital information. When an audio playback device receives the digital information, as well as the corresponding number of bits, and is to access it, the processor of the playback device controls the device in accordance with the received number of bits representing DRM language elements. The processor can directly execute the received number of bits in the same way as an instruction word is executed. By means of this execution, the device is controlled with respect to the rights the device has to the digital information.

By employing this concept, CE devices having limited processing power, such as for example CD players, portable displaying devices and mobile phones, are advantageously relieved from the managing and processing of a complex DRM language and need only process the number of bits sent to them, like processing an instruction word. The device need not interpret any DRM elements, since this is already performed at the server. The devices need not be arranged with an XML parser, which would be the case if they should interpret a DRM language using an XML notation. Neither must the devices have the processing power and storage capacity normally required to manage DRM languages, since a direct execution of the number of bits representing DRM language elements is performed. Therefore, the devices are not required to perform any complex parsing on the received number of bits, since the structure of the number is simple and does not require any advanced processing.

Also, at the server, because of the simple construction of the employed DRM language, it is not necessary to have a software module comprising a full XML parser, since only the core DRM language elements are included. The small number of bits resulting from the mapping performed at the server thus becomes easy to store, process and transmit.

According to an embodiment of the invention, the device is arranged with a memory containing prestored sets of binary digits and corresponding DRM language elements. The processing means in the device is arranged to map the received binary digits against the prestored corresponding DRM language elements. The DRM language elements represented by the received binary digits are thereby derived. The playback device now knows what rights it has to the digital information. This embodiment is advantageous since more complex rights expressions can be employed, but still XML notation parsing need not be performed. The device maps the received binary digits and thus derives the DRM language elements. The device must now interpret each DRM element so that it knows which rights it has to the digital information. The more prestored elements that are included in the memory, the more advanced rights can be expressed.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following. Many different alterations, modifications and combinations will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the invention, as defined by the appended claims.

Embodiments of the present invention will be described with reference made to the accompanying drawings, in which: Fig. 1 shows a schematic system for simplified management of digital rights according to an embodiment of the invention;

Fig. 2 shows a digital right expressed in a simplified DRM language according to an embodiment of the present invention;

Fig. 3 shows another digital right expressed in a simplified DRM language according to an embodiment of the present invention;

Fig. 4 shows yet another digital right expressed in a simplified DRM language according to an embodiment of the present invention; and Fig. 5 shows a schematic system for simplified management of digital rights and the mapping of DRM elements onto binary digits according to an embodiment of the invention.

Fig. 1 shows a system for simplified management of digital rights according to an embodiment of the invention. A server 11 for distributing digital information and accompanying digital rights is arranged to read a DRM language supporting a limited number of rights expressions focusing on core DRM mechanisms. The DRM language preferably conforms to XML, but is not limited to XML only. Other notations could be employed, for example the BNF (Backus Naur Form) notation. The DRM language rights expressions, i.e. the DRM language elements, are read by processing means, such as a CPU 16, contained in the server 11. The server 11 is arranged with storing means in the form of a memory 17 containing the read DRM language elements and sets of bits associated with the elements. From the memory 17, the set of bits corresponding to each read DRM element is derived. The processor 16 then maps each element onto a number of bits by including, in the number of bits, the set of bits corresponding to each read DRM element. The number of bits now represents the rights expressions composed of the elements originally read from the DRM language. The number of bits is provided such that it enables control of the device in accordance with the number of bits. The number of bits can be seen as an instruction word. Some of the reasons for employing a limited number of rights expressions focusing on core DRM mechanisms are that:

(i) each element in the read language is to be stored together with a number of bits representing the element. The more possible elements to read, the larger the storage area 17;

(ii) each element is mapped onto a set of bits. The more elements included, the larger the set of bits. Since sets of bits are put together to form the previously described number of bits to be executed by a processor in a CE device, it is advantageous if the set of bits is rather small. (iii) each element must be parsed at the server 11. A limited number of elements results in a less complex parser. Moreover, each element is later interpreted in the form of an instruction word by means of the CE device processor executing the instruction word. The less elements, the smaller the number of instruction words. The number of bits, i.e. the representation of the digital rights, is then distributed together with some digital information, such as an audio file. This distribution can occur in many different ways. In Fig. 1, the distribution is effected via an open network 12, for example the Internet. A computer 13 can be employed to download an audio file and corresponding digital rights in the form of a number of bits via the network 12 from the server 11. The digital information and the set of bits are burned onto a CD-R 15 and placed in a playback device in the form of a CD player 14.

When the CD player 14 receives the digital information and accesses it, the processor 18 of the playback device executes the number of bits on the CD-R 15 as an instruction word and thereby controls rights the CD player 14 has to the digital information. The CD player 14 now know what rights it has to the digital information on the CD-R 15. The rights could, for example, be of the type "Play unlimited for one week", "No copying allowed" etc. When distributing the digital information from the server 11 to the computer 13 via the network 12, it is possible that the computer 13 has to interpret the set of bits to validate that it actually has the right to burn the digital information onto the CD-R 15.

As mentioned earlier, the present invention enables CE devices, such as for example CD players, to be relieved from the managing and processing of complex DRM languages and need only process the number of bits presented to them. The digital rights are derived by simple processing, and the devices need not be arranged with XML parsers, powerful processors and large memories. Advantageously, the devices are not required to perform parsing on the received number of bits, since the structure of the number of bits is simple and executed like an instruction word. This eliminates requirements on advanced computer processing. The present invention can of course be employed by devices with more processing power, but it has a larger impact on computationally weak CE devices. Note that it is possible that authentication may occur between any two, or more, of the appliances comprised in the present invention. This would require the distributed information to be provided with some identifier or authenticator, for example in the form of an identification number or some type of encryption or digital signature. Authentication is typically used to improve the security in a system. Optionally, information is encrypted to prevent unauthorized third parties from eavesdropping on the network and accessing/stealing the distributed information.

As has been mentioned above, the distribution of digital information and corresponding digital rights can be effected in a number of different ways. Possibly, the distribution is made from an information provider server to a retailer of information. The information is thereafter distributed from the retailer to a customer. The retailer or the provider can thus handle the placing of the information on a media, such as a CD-R, a video cassette, a DVD etc.

The end user can be part of a so called Authorized Domain (AD). The concept of authorized domains tries to solve the problem of how to serve the interests of the content owners (who want protection of their copyrights) as well as the interests of the content consumers (who want unrestricted use of the content). The basic principle is to have a controlled network environment in which content can be used relatively freely as long as it does not cross the border of the authorized domain. Typically, authorized domains are centered around the home environment. Of course, other scenarios are also possible. A user could for example take a portable television with him on a trip, and use it in his hotel room to access content stored on his Personal Video Recorder at home. Even though the portable television is outside the home network, it is a part of the authorized domain of the user.

Fig. 2 shows a digital right expressed in a simplified DRM language (sDRML) according to an embodiment of the present invention. The sDRML uses XML notation, and all elements located between <Right> and </Right> in Fig. 2 forms the digital right expressed in sDRML. The functionality of the sDRML code given in Fig. 2 can be described as:

"Anyone within a group is allowed to play "Stay" by U2 using any device and any media"

General pseudo code for this functionality can be expressed as:

ConsumerGroup is allowed to OperationList with ContentlD using DeviceList on

MediumList.

For this specific example, the pseudo code would look like: Any is allowed to play with U2-Stay using any on any.

The ConsumerGroup option included in the digital right could imply that the digital information typically is distributed in a controlled network such as an AD. It could also imply that a specific user, which is part of an AD, is designated. This will be shown later. The main advantage with ADs is that they provide a compliant environment and can therefore be trusted. Thus, it is easier to control the access to digital information within an AD than it is in an open network. Some more examples on digital rights expressions will be given before the actual mapping of elements onto binary digits is described in detail.

Fig. 3 shows another digital right expressed in sDRML. The functionality of the sDRML code given in Fig. 3 can be described as:

"Alice is allowed to play track A and B of CD C using any device for one month starting from 5 April 2002".

For this specific example, the pseudo code would look like: Alice is allowed to play with A and B using any on C from 5 April 2002 until 5 May 2002.

When a specific user is designated, in this case Alice, it might be necessary for Alice to authenticate herself to the playback device used to play the digital information. This can, for example, be done with a simple password procedure. Fig. 4 shows yet another digital right expressed in sDRML. The functionality of the sDRML code given in Fig. 4 can be described as:

"Bob is allowed to make three copies on content C and can also play it on any device and medium".

For this specific example, the pseudo code would look like:

Bob is allowed to play copy subject to count is 3 with C using any on any.

As can be seen from the given examples, sDRML is a non-recursive language, making it less complex and easier to handle than a recursive language. Now, when sDRML and possible digital rights that can expressed using sDRML have been described, the mapping of elements onto binary digits will be described. The mapping can be performed as follows:

• Consumer ID is mapped onto k bits,

• Operation ID is mapped onto 1 bits,

• Content ID is mapped onto m bits,

• Device ID is mapped onto n bits,

• Medium ID is mapped onto o bits, • Count is mapped onto p bits,

• Generation is mapped onto q bits

• Time is mapped onto r bits.

The actual values of k...r depend on the specific implementation. A right is mapped onto k+1+m+n+o+p+q+r bits. Assuming that we have the digital right as expressed in Fig. 2, the mapping of elements onto bits can be done according to the following:

• Consumer ID "Any" is mapped onto "000" • Operation ID "Play" is mapped onto "010"

• Content ID "U2-Stay" is mapped onto "011"

• Device ID "Any" is, as in the Consumer ID case, mapped onto "000"

• Medium ID "Any" is, as in the foregoing case, mapped onto "000"

• Count and Generation are mapped onto "111", respectively. "I l l" stands for "unrestricted".

• Time is mapped onto "00000". The resolution on this parameter can, for example, be one day. "00000" stands for "unlimited" or "not defined".

The actual mapping format could, for example, be in the form [Consumer ID, Operation ID, Count, Generation, Content ID, Device ID, Medium ID, Start, End]. The specific right expressed in Fig. 2 would thus consist of the following set of bits:

000 010 111 111 011 000 000 00000 00000 (1)

The actual mapping performed in accordance with an embodiment of the present invention is described with reference to Fig. 5. The digital right used to exemplify the mapping is the right shown in Fig. 2. The processor of a server 51 parses and reads the right expressed in sDRML. The server 51 is arranged with storing means in the form of a memory containing the read DRM language elements and sets of bits associated with the elements. A part of the content of the memory is shown in box 56. From the memory, the binary representation corresponding to each read DRM element is derived. "Any" corresponds to "000", "play" corresponds to "010" etc. The processor then maps each element onto a number 57 of bits by including, in the number 57 of bits, the set of bits corresponding to each read DRM element. The number 57 of bits now represents the right as shown in Fig. 2. The number 57 of bits is provided such that it enables control of the device 54 receiving the number 57 of bits.

The number 57 of bits, i.e. the representation of the digital rights, is then distributed together with some digital information, such as an audio file, via a network 52. Note that the digital rights alternatively can be distributed separate from the information. A computer 53 downloads the audio file and the number 57 of bits via the network 52 from the server 51. The digital information and the number 57 of bits are burned onto a CD-R 55 and placed in a CD player 54.

When the CD player 54 receives the digital information and is to access it, the processor of the CD player 54 inteφrets the number 57 of bits on the CD-R 55 and derives the digital rights from this inteφretation. A memory in the CD player 54 contains the received set of bits and prestored corresponding DRM language elements. A part of the content of the memory is shown in box 58. The inteφretation is performed by mapping the number 57 of bits to the prestored corresponding DRM language elements contained in the CD player memory. For example, "000" corresponds to "any", "010" corresponds to "play" etc. The DRM language elements represented by the received number 57 of bits are then derived. The CD player 54 now knows what rights it has to the digital information on the CD-R 55.

The actual bits representing each element in the read DRM language can be formed in many different ways, for example "Any" might be represented by "111" instead of "000". Also the number of bits that constitutes the digital rights does not necessarily have the form [Consumer ID, Operation ID, Count, Generation, Content ID, Device ID, Medium ID, Start, End]. The key issue is that the server that creates the number of bits and the device which is to derive the digital right from the number of bits use the same representation. Given the number of bits (1), the device will map the three first bits, "000" to ConsumerlD = any, the next three bits, "010", to OperationID = play and so on. The structure of the number of bits is very simple and enables direct reverse mapping by a device, thereby deriving the digital rights composed of the sDRML elements.

As can be seen, the representation of the rights expressed in a simplified DRM language, such as sDRML, focusing on core DRM mechanisms, by means of a number of bits, strongly simplifies the managing of digital rights. At the server, the parsing of the sDRML semantics are quite simple because of the non-complex structure of sDRML. The storing and transmitting of the set of bits representing the digital rights becomes easy due to the small-size set of bits. At the CE device, a complex DRM language need not be parsed, processed and managed. Only the set of bits presented to the device need to be processed. Another advantage is that the CE device is not required to perform parsing on the received set of bits, since the structure of the set is simple and easy to inteφret and process.

It should be noted that the above mentioned embodiments exemplify the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device claims enumerating several means, several of these means can be embodied by one and the same item of hardware.

Claims

CLAIMS:

1. A method at a server for simplified management of digital rights, the method being characterized in that it comprises the steps of: reading DRM language elements; deriving, from a storage area containing the read DRM language elements and sets of biliary digits associated with the elements, the set of binary digits corresponding to each read DRM element; and mapping the read DRM elements onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element, wherein the number of binary digits is provided such that it enables control of a device receiving the number of binary digits.

2. A server for simplified management of digital rights, the serverbeing characterized in that it comprises: processing means; and storing means; wherein said storing means is arranged to store DRM language elements and sets of binary digits associated with the elements; said processing means is arranged to read DRM language elements, to derive the set of binary digits corresponding to each read DRM element from said storing means and to map the read DRM elements onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element, wherein the number of binary digits is provided such that it enables control of a device receiving the number of binary digits.

3. A method at a device for simplified management of digital rights, the method being characterized in that it comprises the steps of; receiving binary digits representing DRM language elements; and controlling the device in accordance with the received binary digits representing DRM language elements.

4. The method according to claim 3, further comprising the step of: reading prestored sets of binary digits and corresponding DRM language elements; and wherein the step of controlling the device includes mapping the received binary digits against the prestored corresponding DRM language elements, wherein the DRM language elements represented by the received binary digits are derived.

5. A device for simplified management of digital rights, the device being characterized in that it comprises: receiving means arranged to receive binary digits representing DRM language elements; and processing means arranged to control the device in accordance with the received binary digits representing DRM language elements.

6. The device according to claim 5, the device further comprising: storing means containing prestored sets of binary digits and corresponding DRM language elements; and wherein said processing means is arranged to map the received binary digits against the prestored corresponding DRM language elements, wherein the DRM language elements represented by the received binary digits are derived.

7. A method at a system for simplified management of digital rights, the method being characterized in that it comprises the steps of: reading, at a server, DRM language elements; deriving, from a storage area at said server, which area contains the read DRM language elements and sets of binary digits associated with the elements, the set of binary digits corresponding to each read DRM element; mapping, at said server, the read DRM elements onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element, wherein the number of binary digits is provided such that it enables control of a device receiving the number of binary digits; distributing, from said server, the number of binary digits to a device; receiving, at the device, the number of binary digits representing DRM language elements; and controlling the device in accordance with the received number of binary digits representing DRM language elements.

8. The method according to claim 7, further comprising the step of: reading, at the device, prestored sets of binary digits and corresponding DRM language elements; and wherein the step of controlling the device includes mapping, at the device, the received number of binary digits against the prestored corresponding DRM language elements, wherein the DRM language elements represented by the received number of binary digits are derived.

9. A system for simplified management of digital rights, the system being characterized in that it comprises: a server including a first processing means, first storing means and transmission means; and a device including a second processing meansand receiving means; wherein said first storing means is arranged to store DRM language elements and sets of binary digits associated with the elements; said first processing means is arranged to read DRM language elements, to derive the set of binary digits corresponding to each read DRM element from said storing means and to map each read DRM element onto a number of binary digits by including, in the number of binary digits, the set of binary digits corresponding to each read DRM element, wherein the number of binary digits is provided such that it enables control of the device receiving the number of binary digits; said transmission means is arranged to distribute the number of binary digits to said device; said receiving means is arranged to receive the number of binary digits representing DRM language elements; and said second processing means is arranged to control the device in accordance with the received number of binary digits representing DRM language elements.

10. The system according to claim 9, wherein the device comprised in the system further comprises: a second storing means containing prestored sets of binary digits and corresponding DRM language elements; and wherein said second processing means is arranged to map the received number of binary digits against the prestored corresponding DRM language elements, wherein the DRM language elements represented by the received number of binary digits are derived.