DE102005012878B4 - A method for the secure use of copyright-protected data on multiple computers by using multiple keys - Google Patents

Abstract

A method of providing copyrighted data in which, upon request of an authorized user's computer, such data is encrypted by a data server (200) over any telecommunications network to the user's computer and through an on-computer individualized decryption module can be decrypted for use, wherein the encryption of data to be transmitted from the data server (200) to the computer using a key (software key) uniquely assigned to the decryption module, wherein the requested data in an encrypted manner in such a record to the requesting computers (100, 110, 120, 130, 140) (201, 202) are decrypted to use them by a number of uniquely defined, individualized decryption modules defined on encryption during encryption In addition, with the request transmitted by the requesting computer, a data record is transmitted (101) which comprises a plurality of individualization information (software II (i)) uniquely assigned to each individualized decryption module, characterized in that the respective individualization information is provided individual key (software key (i)) of the decryption module is used.

Description

The invention relates to a method for providing copyright-protected data, in which the data are transmitted at the request of an authorized user of a data server in an encrypted manner via a substantially arbitrary telecommunications network to a connectable to the telecommunications network computer of the user and by a on the Computer-implemented, individualized decryption software can be decrypted for use.

In order to ensure copyright protection of digital data, which can also be retrieved via the Internet, for example, so-called Digital Rights Management (DRM) systems are used which provide the data in encrypted form. In order to use such data protected by encryption of copyrighted data on an authorized user's computer conventionally an individualized decryption software is necessary, which essentially comprises an individual key uniquely assigned to a respective user in order to largely rule out abuse. Usually, this is realized by the fact that each user must install other software or that each user can install the same software, but this is individualized after installation, for example, established and connected to the corresponding DRM system via the Internet individual key is downloaded.

Furthermore, in most cases, the software is designed in such a way that it is possible to decrypt the copyright-protected digital data by means of encryption, but these can only be viewed in a specific manner, but the data to be decrypted can not be accessed directly. Otherwise, a change and / or storage and thus a substantially arbitrary further use and / or distribution of the decrypted data would be given. For essentially the same reason, the key used by the software is protected by lock mechanisms so that access to it by a user is also excluded, since otherwise the user could decrypt such data himself.

The DRM system usually comprises the identification of the respective software used, the corresponding encryption of the user-side data to be protected, and the transmission of the encrypted data via a data / communication channel to the user or a computer used by the user institutions.

The general procedure for the use of copyright-protected data thus initially comprises the establishment of a data transmission connection between the user, that is to say essentially a computer used by the user, and a corresponding DRM system, in particular via the Internet. As a result of this, the desired data can be requested from the DRM system via a portal, whereby the DRM system manually or automatically transmits the necessary information about the respective software for identification via the integrated software.

The DRM system then encrypts the data according to the identified software, that is with a software integrated or assigned key, hereinafter generally referred to as a "software key".

By encrypting the requested data based on the respective software key corresponding cipher franchises are thus individually provided and then transferred to the computer. After transmission, the decryption of the encrypted data, that is to say the cipher data, takes place again by using the key integrated or assigned to the decryption software, so that the decrypted data can be displayed.

In modified form, it is sometimes provided that instead of a key two keys are used. In this case, the data are initially encrypted by the DRM system with a fixed data key, hereinafter generally referred to as a "data key", once for all users, hereinafter referred to as a data key cipher. This data key is also further encrypted in response to a corresponding data request by a user with the individual key of the respective user, ie with the aforementioned software key. The unencrypted original data is thus encrypted only once. The amount of data of the data key that is repeated several times, i. is individually encrypted, is generally smaller than that of the unencrypted data, so that the individual encryption of the data key requires less effort. The user is thus transferred the data key cipher and the data key encrypted with the individual key.

A significant disadvantage of the aforementioned variants, however, is that a user can essentially only use the requested data with the corresponding individualized software, because only this one contains the appropriate key.

One way to get the requested data on multiple computers by the same user to use is to customize the software in the same way on all these computers. On the one hand, this can be prevented by anti-abuse protection mechanisms built into the software. On the other hand, the legitimate implementation of the individualized software on different computers in certain scenarios can be very expensive. For example, if a student in a university library downloads a document and then wants to use it at home, he would need to personalize the software in the library so that it contains the same key as his software at home, or he can save the data not use on both computers. Significant disadvantages here are that a subsequent student on the same library computer in case of doubt, the software has to re-individualize himself and the aforementioned first student the next time a DRM system based data request, using the same or another library computer, the software again needs to be individualized. Moreover, if customization is hardware-dependent, it is even completely impossible to customize different computers in the same way.

Another possibility would be that the user has to download the data from each computer used by him again from the DRM system or must be transferred, which must then suitably for the requesting computer to re-encrypt the data. This brings an additional expense for both the user and for the DRM system and possibly different copies of the same data on different computers, so that a data comparison is difficult or impossible to carry out.

The object of the invention is thus to show a technical solution with which the secure provision of copyright-protected data on multiple computers of a user is ensured in a simple manner.

The solution according to the invention is given in a most surprising way already by the article having the features of a dependent independent claim. Advantageous and / or preferred embodiments and further developments are the subject of the dependent claims.

Starting from the JP 2000-358 003 A Accordingly, the invention provides a method for providing copyright-protected data in which, upon request of an authorized user's computer, such data is encrypted by a data server over a substantially arbitrary telecommunications network to the user's computer and transmitted through the computer Computer-implemented, individualized decryption module can be decrypted for use, wherein the encryption of data to be transmitted from the data server to the computer using a key unique to the decryption module is performed, the requested data in an encrypted manner in a record to the requesting computer be transferred for use of the data by a specified during the encryption number of clearly defined, individualized decryption modules on different computers Use can be decrypted, wherein the request transmitted from the requesting computer, a record is transmitted, which comprises a plurality of each individualized decryption module unique individualization information. The invention is characterized in particular by the fact that the respective individual key of the decryption module is used as individualization information.

The transmitted, requested digital and encrypted data can thus be exchanged in the easiest manner between individual predefined computers, each with a differently individualized decryption module, for the corresponding on-site decryption, whereby a decryption module comprising software and / or hardware can be used for the specific application.

For this purpose, in particular, it is proposed that the requested data record be encrypted several times by using different keys, which are each uniquely assigned to another particular individualized decryption module, and a data record is transmitted to the requesting computer, in which the respective differently encrypted data is embedded in the requested data become.

In particular, in order to reduce the encryption effort and / or the amount of data to be transmitted, it is further provided according to a particularly preferred embodiment that for encrypting data to be transmitted to the user, the requested data is first pre-encrypted using a common data key and this common data key then encrypted with respective uniquely assignable software keys. For this purpose, the common data key is stored in an application-specific manner in a memory allocated to the server, for example a database, or in response to a request for transmission of copyright-protected data generates a server associated with the generation device.

According to one embodiment, when selecting the respective keys to be used, a memory, e.g. a database is accessed in which a list is maintained by a respective requesting computer and / or user respectively assigned, implemented on different computers, individualized decryption modules.

In further development, in order to further increase security, it is envisaged that the respective individual keys are encrypted prior to transmission of the request data record using a common system key stored on the computers with the respective implemented individualized decryption module, and the server accesses a memory, e.g. a database in which the system key is held, first decrypting the encrypted customization information contained in the request data set to obtain the key selected for encrypting the requested data.

It is also advantageous if the system key and / or software key stored in the computers is stored so that it is unobservable to the user, in particular read / write protected, so that unauthorized access by the user is precluded.

In order to adapt the invention in a simple manner specific to the application, embodiments are proposed in which a key assigned uniquely to an individualized decryption module is used once or in a repetitive manner in response to the respectively implemented decryption software using random numbers and / or hardware properties of the respective computer is generated.

Furthermore, this is application-specific useful if the respective decryption module is assigned a hardware token for their use.

In addition, the unreadable storage of system key and / or software key for a user can be done by and in particular within the hardware token.

In an embodiment which is particularly simple to implement, the individualization information used is an identifier uniquely assigned to each decryption module, such as e.g. a registration code.

According to a preferred refinement, it is provided that the server determines and / or generates the respective key selected for encrypting the requested data using a derivation function accessible by the server from the respective identifier.

Derivative functions that use a keyed hash function, an encryption algorithm and / or a signature algorithm have proven to be expedient.

As a preferred alternative to the derivative function, the invention contemplates using a memory associated with the server, e.g. a database, in which for each software identifier a unique associated key is kept.

The invention thus further comprises a computer-readable storage medium having electronically readable data which, read by a computer, interacts with the computer to provide and / or utilize copyright-protected data according to the method of the invention.

• 1 schematisch ein allgemeines Funktionsschema betreffend die Übertragung eines bevorzugten Anforderungsdatensatzes von einem anfordernden Computer an einen DRM-Server und die Rückübertragung von auf den angeforderten Daten basierenden, verschlüsselten Dateneinheiten umfassenden Datensätzen nach der Erfindung,
• 2 schematisch ein beispielhaftes Funktionsschema zur Bestimmung der jeweils auszuwählenden Schlüssel auf Seiten des Servers nach der Erfindung, und
• 3 schematisch ein Funktionsprinzip betreffend die Entschlüsselung empfangener verschlüsselter Dateneinheiten zur Nutzung der angeforderten Daten auf unterschiedlichen Computern mit jeweils implementierter individueller Entschlüsselungssoftware nach der Erfindung.

Further features and advantages of the invention will become apparent from the following exemplary description of preferred embodiments with reference to the accompanying drawings. In the drawings show:

• 1 12 schematically illustrates a general functional diagram relating to the transmission of a preferred request data record from a requesting computer to a DRM server and the retransmission of data records according to the invention comprising data records based on the requested data-based encrypted data units;
• 2 schematically an exemplary functional scheme for determining the respective key to be selected on the server side according to the invention, and
• 3 schematically an operating principle relating to the decryption of received encrypted data units to use the requested data on different computers, each with implemented individual decryption software according to the invention.

The following is first of all in particular 1 Referenced.

1 In a very simplified manner, a general functional diagram relating to the transmission of three different request data records according to the invention from a requesting computer of an authorized user to a DRM server is shown and the retransmission of encrypted data units based on the requested data in functional dependence of a respective request record.

Presented at 1 is a user's computer assembly labeled 100 that is entitled to use encrypted, copyrighted data. The computer assembly is a number of individual computers 3 labeled 110, 120, 130 and 140, assigned, each of which has implemented an application-specific trained and each individualized software for decryption.

The computers can be networked with each other or are separated from each other, so that a data exchange is possible only with portable storage.

Through a telecommunication system labeled 300, such as the Internet, at least one of the computers of the computer arrangement 100 is in communication with a server 200 which, upon request, encrypts corresponding copyright-protected digital data to the requesting computer of the computer device 100 transfers.

The server 200 is thus in particular part of a not-so-called "Digital Rights Management" (DRM) system.

If the user requests data requested by him in the first step, the computer will issue the order 100 interacting with the software implemented thereon, an application-specific request data record to the server 200 transmitted 101.

For this purpose, such a request data record comprises an identifier "data ID" identifying the desired data, for example a unique request code or an order / article number. In addition, a desired software to be used by the user for decryption is transmitted to server 200 with respect to identifying individualization information "SoftwareII (i)", wherein the index i designates the number of software versions or the number of computers on which the user respectively individualized software has implemented with which he wants to use the data in the future. For example, he sends the customization information with the library software and his own software at home.

It should be noted that, in modification, the selection of a data identifier and the specification of the software customization information, for example, only after connection to the server 200 can be performed via a portal provided to the user.

The number of computers allowed or individualized versions of software allowed for use may be limited by the DRM system or the server providing the copyrighted data.

at 1 Three different types of software customization information software II (i) are displayed.

For one, the respective

Software customization information is a simple identifier "SoftwareID (i)", such as be a registration code. Based on this, the server determines, as described in more detail below, the corresponding software keys associated with the respective individualized software with which the data is encrypted prior to transmission.

On the other hand, the respective

Software customization information directly the respective software key associated with an individualized software (i).

To further increase the security, this is expediently re-encrypted, as indicated in the third alternative, e.g. with a common system key, hereinafter referred to as "system key", although the server, but not the user knows, that is, this is stored inexplicably for the user, for example, hidden in the decryption software.

Basically, it can be assumed that the user knows neither the individual software key software key (i) nor the system key, since otherwise he or she could decrypt the data himself.

For example, in the respective computers on which the decryption software is implemented, the respective software key (i) is stored in each case inexplicable for the user, for example hidden in the decryption software. To be on the part of the user from a computer from the respective, belonging to another individualized decryption software software key (i) bundled to the server 200 Thus, for example, the user is able to read / write protected by means of transportable memory so portable for the user that the respective software key (i) may be transmitted by a "foreign" decryption software for transmission to the server 200 usable, but only can be used by the "belonging" decryption software for decryption.

The following is also on 2 Reference is made, which schematically shows an exemplary functional scheme for determining the respective applicable decryption software and thus the respective key for encrypting the requested data on the server 200 side.

As in 2 to see, the server speaks 200 on received ( 101 ) Software customization information software II (i) such that it is first checked whether the software II (i) is in the form of an identifier SoftwareID (i).

$${\text{f}}_{\text{Ableitung}}\left(\text{SoftwareID2}\right)=\text{Software-Key 2}\text{,}$$

usw....If so, the server forwards 200 according to a first embodiment from the software identifier by means of a derivative function "f" from the corresponding software key. Expediently, a secret, for example a secret key, is additionally added to the derivation 2 used as "Derivation", that is, the key Software Key (i) to be used by the server for encryption is given by: $${\text{f}}_{\text{derivation}}\left(\text{SoftwareID1}\right)=\text{<figure-callout id="1" label="Software Key" filenames="DE102005012878B4\_0013.png,DE102005012878B4\_0014.png" state="{{state}}">Software Key</figure-callout> 1}\text{.}$$

$${\text{f}}_{\text{derivation}}\left(\text{SoftwareID2}\right)=\text{<figure-callout id="2" label="Software Key" filenames="DE102005012878B4\_0015.png" state="{{state}}">Software Key</figure-callout> 2}\text{.}$$

etc....

Such a derivative function may be, for example, a so-called "keyed hash function", an encryption algorithm and / or a signature algorithm.

In an alternative embodiment, according to 2 instead of deriving the respective software key from the SoftwareID, the server also accesses a database in which a uniquely associated software key is stored for each software ID, that is, maintained.

If the check indicates that the software II (i) does not exist in the form of an identifier SoftwareID (i), it is checked whether the software II (i) is directly the respective software key (i) associated with an individualized software.

$${\text{decrypt}}_{\text{System-Key}}\left(\text{Software-Key 2}\right)=\text{Software-Key 2}\text{, usw}\text{.}$$

If the check indicates that the software II (i) is not directly the respective software key (i) associated with an individualized software, the exemplary embodiment on which the description is based assumes that the software key (i) is encrypted, So it has been transmitted by encryption with the common system key "system key". In this case, the respective software key (i) is determined by decoding the software ID (i), ie the encrypted software key (i), based on the system key $${\text{decrypt}}_{\text{System-Key}}\left(\text{Software Key 1}\right)=\text{<figure-callout id="1" label="Software Key" filenames="DE102005012878B4\_0013.png,DE102005012878B4\_0014.png" state="{{state}}">Software Key</figure-callout> 1}\text{.}$$

$${\text{decrypt}}_{\text{System-Key}}\left(\text{Software Key 2}\right)=\text{Software Key 2}\text{, etc}\text{,}$$

Consequently, the respective software key underlying the decryption software can also be determined with the identified software key.

Coming back to 1 Upon receipt of the data request set and identification of the respective software based on the respectively identified software II, the encryption of the data to be transmitted is initiated. Optionally, according to 1 also from the server 200 or an associated unit initially checked to see whether for the Chiffredaten to be transmitted first a uniform encryption of the requested data (D) with additional use of a common data key (DK) to be performed with subsequent individual encryption of the data key (DK).

The use of a common data key (DK) may e.g. be useful to reduce the encryption and / or transmission costs, if, in particular depending on the number of identified software, the amount of data requested copyright data over the amount of data of a common data key exceeds a predetermined limit.

The use of a common data key (DK), however, can also be predetermined for the application.

$${\text{encrypt}}_{\text{Software-Key2}}\left(\text{Daten}\right)=\text{Chiffredaten}\left(\text{2}\right)\text{,}$$

Performs according to 1 the verification of the result of providing the cipher handovers to be transmitted without additional use of a common data key becomes the requested data for the number "n" of identified software versions from the server 200 then encrypted with the respective corresponding key so in particular according to $${\text{encrypt}}_{\text{Software Key1}}\left(\text{dates}\right)=\text{cipher data}\left(\text{1}\right)\text{.}$$

$${\text{encrypt}}_{\text{Software Key2}}\left(\text{dates}\right)=\text{cipher data}\left(\text{2}\right)\text{.}$$

This number of individual ciphers based on the requested data (i), at 1 with [cipher (i) _(D) ] with i designated from 1 to n, thus corresponds to the number "n" of identified Software versions and will then be sent to the computer 100 transmit 201.

Performs according to 1 checking for the result of providing the cipher handlers to be transmitted using an additional shared data key, the requested data is first encrypted using this fixed data key.

zunächst in ein für alle Nutzer bzw. für jede Software gleiches Daten-Key-Chiffre umgewandelt oder liegen bereits als solches vor.Specifically, therefore, the requested data by a function $${\text{encrypt}}_{\text{Data Key}}\left(\text{dates}\right)=\text{Data-key cipher}$$

initially converted into a for all users or for each software the same data key cipher or are already present as such.

$${\text{encrypt}}_{\text{Software-Key2}}\left(\text{Daten-Key}\right)=\text{Chiffredaten }\left(\text{2}\right)\text{,}$$

The data key is then individually encrypted with the respectively identified individual keys software key (i), thus in particular according to $${\text{encrypt}}_{\text{Software Key1}}\left(\text{Data Key}\right)=\text{cipher data}\left(\text{1}\right)\text{.}$$

$${\text{encrypt}}_{\text{Software Key2}}\left(\text{Data Key}\right)=\text{cipher data}\left(\text{2}\right)\text{.}$$

In this case, a number of individual key data (i) based on the common data key is thus generated corresponding to the number "n" of identified software versions.

It should be noted that the encryption of requested data using a fixed data key does not have to take place after requesting this data but may have already been carried out in advance. However, individual encryption of this data key also takes place in this case only after appropriate request.

This number of individual ciphers (i), at 1 with [cipher (i) _(DK) ] with i from 1 to n is added together with the data key cipher based on the requested data 1 with cipher (DK) _(D) , to the computer 100 transmit 202.

After receiving the server 200 transferred to Cipher, at 3 Generally designated with cipher, at the requesting computer assembly 100 , the encrypted data, for example via removable storage units for each decryption to the individual for the computer arrangement 100 the server 200 displayed computer 110 . 120 . 130 and 140 on which an individualized software identified in the data request set is or will be implemented.

With the on the computer 110 Implemented and individualized software, the data can eg with the associated software key 1 be decrypted on the computer 120 with the software key 2 on the computer 130 with the software key 3 and, at the computer 140 with the software key 4.

The respective software can thus decrypt the individual keyframes (i) again using the corresponding individual key.

If the individual cipher franchises (i) are based on the requested data, then after decryption of the individual cipher franchises (i) the requested data are immediately available, ie $${\text{decrypt}}_{\text{Software Key}\left(\text{i}\right)}\left(\text{cipher}\left(\text{i}\right)\right)=\text{dates}\text{,}$$

Insofar as the individual cipher franchises (i) are based on the data key, after decryption of the individual cipher franchises (i) with the respective individual key, the fixed data key is initially available, ie $${\text{decrypt}}_{\text{Software Key}\left(\text{i}\right)}\left(\text{cipher}\left(\text{i}\right)\right)=\text{Data Key}\text{,}$$

At the respective computers 110 . 120 . 130 and 140 Thus, the requested data at only by subsequent subsequent decryption of the transmitted with data key cipher, at 3 denoted by cipher (DK), decrypted using the respective previously decrypted fixed data key, as indicated by the dashed arrows marked 202, ie $${\text{decrypt}}_{\text{Data Key}}\left(\text{cipher}\left(\text{DK}\right)\right)=\text{dates}\text{,}$$

In addition to the above description, the invention also includes modified embodiments in which a hardware token, for example a chip card, is used for decryption, which application-specifically interacts with a respective computer and / or the decryption software implemented on the computer. Also, as an alternative or in addition to the decryption by software application specific hardware can be used.

In a further preferred embodiment, it is further provided that the respective software key (i) is generated by the decryption software from random numbers and / or hardware properties once, in particular upon first access to the decryption software by a user, or in a repeated manner. Again, the interaction with a hardware token is appropriate.

The invention further includes embodiments in which the server 200 or a cooperating unit has stored an association of users and / or computers and individualized, different decryption software. In this case, only the user needs to be identified by the data request set and the selection of the individual software keys is done by means of the stored assignment.

Claims (15)

A method of providing copyrighted data in which, upon request of an authorized user's computer, such data is encrypted by a data server (200) over any telecommunications network to the user's computer and through an on-computer individualized decryption module can be decrypted for use, wherein the encryption of data to be transmitted from the data server (200) to the computer is performed using a key (software key) uniquely assigned to the decryption module, wherein the requested data in an encrypted manner in a record the requesting computer (100, 110, 120, 130, 140) are transmitted (201, 202) to use it for encryption by means of a number of uniquely defined, individualized decryption modules specified on the encryption on different computers can be sselt, further transmitted with the data transmitted by the requesting computer request a record (101) having a plurality of in each case a different individualized decryption module unambiguously assigned individualization information (SoftwareII (i)), characterized in that the individualizing information of the respective individual key (software key (i)) of the decryption module is used. Method according to the preceding claim, further characterized in that the requested data are encrypted several times by using different keys (software key (i)), which are each uniquely assigned to a different particular individualized decryption module, and a data record is transmitted to the requesting computer, in which the differently coded data (cipher (i)) based on the requested data are embedded. Method according to Claim 1 , further characterized in that the requested data once by using a predeterminable via the data server key (data key) and this predetermined key several times by using different keys (software key (i)), each assigned to a different particular individualized decryption module are encrypted, and a record is transmitted to the requesting computer, in which the data based on the requested data encrypted data (cipher (DK)) and based on the predetermined key each differently encrypted data (cipher (i)) are embedded. Method according to Claim 3 , further characterized in that the predefinable key is held in memory associated with the server or generated in response to the data request of a computer by a device associated with the server. Method according to one of the preceding claims, further characterized in that, in the selection of the respective keys to be used, a memory is accessed in which a list is maintained by a respective requesting computer and / or user respectively assigned, individualized decryption modules implemented on different computers becomes. Method according to one of the preceding claims, further characterized in that the respective individual key is encrypted prior to transmission of the request data record using a common system key assigned to the individualized decryption module implemented on the computers and the server accessing a memory in which the system key is initially maintained, a decryption of the encrypted customization information contained in the request data set to obtain the key selected for encrypting the requested data performs. Method according to one of the preceding claims, further characterized in that a respective the individualized decryption module associated system key and / or individual key in a computer or acting together with this hardware token for the user secluded, especially read / write protected, stored for the user , Method according to one of the two preceding claims, further characterized in that the individual key uniquely assigned to an individualized decryption module is automatically or once generated in response to the respectively implemented decryption module using random numbers and / or hardware properties of the respective computer. Method according to one of the preceding claims, further characterized in that a hardware token is assigned to the respective decryption module for their use. Method according to one of the preceding claims, further characterized in that an identifier (SoftwareID (i)) uniquely assigned to each decryption module is used as individualization information. Method according to the preceding claim, further characterized in that the server (200) determines and / or generates the respective key selected for encrypting the requested data by using a derivation function accessible by the server (200) from the respective identifier. Method according to the preceding claim, further characterized in that a keyed hash function, an encryption algorithm and / or a signature algorithm is used as the derivation function. Method according to one of the three preceding claims, further characterized in that in a memory associated with the server to each software identifier a unique associated key is kept. Method according to one of the preceding claims, further characterized in that a decryption module comprising software and / or hardware is used as the decryption module. A computer readable storage medium having electronically-readable data that, when read by a computer, interacts with the computer to provide and / or benefit from copyright-protected data as claimed in any preceding claim.

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