CN101459508B - Content ciphered key exchange method for digital copyright management system - Google Patents
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Abstract
A content encryption key switching method of a digital copyright management relates to the technical field of the digital copyright management, which aims to solve the technical problems of easy replacement and difficult declassification of CEK. The CEK switching method lies in the RO prerelease and a switching time window. The RO prerelease means that copyright issuers (RI) issue RO including CEK to a client terminal device before the CEK switching prepared for the switching of CEK. As the clocks of all devices of a system have deviation unable to realize the complete synchronization of switching time, and a switching time window is set for assuring the client terminal device to normally use digital information products under the condition of existing slight deviation between the time of the client terminal device and the time of a server. The switching time window comprises a front window and a back window, which is a unified parameter inside a system, and is uniformly allocated and managed by a middleware without easily changing. The CEK switching method of the invention has the characteristics of each replacement and difficult declassification.
Description
Technical field
The present invention relates to digital copyright management (DRM) field, relate in particular in the DRM system, the method that contents encryption key (CEK) switches.
Background technology
In the DRM system, the digital information product that content publisher (CI) provides is published on the network after encrypting through CEK.Client device will use the digital information product such as (comprise online broadcast, check, downloading and playing operation) in advance like this, just must obtain corresponding CEK, the common customer end also needs to obtain to use the associated rights of this digital information product, as play, check, the restriction such as access times, service time.In the DRM system, CEK generally will pass through and encrypt, and combines with digital information product rights of using, forms right objects (RO), and RO generally is the requirement integrity protection.The digital information product of RO and process encipherment protection generally arrives client devices through two different approach, and the digital information product of wherein encrypting may be the form with information flow, also may arrive client device with the form of file.DRM terminal agent (DRM Agent) the control client device that resides in client device uses the digital information product with the authority that RO gives.The basic thought of DRM system that Here it is.
In the DRM system, as the important content of RO, protection and the distribution of CEK have consequence.CEK must store, transmit, use in the mode of safety.Along with DRM in field extensive uses such as IPTV, electronic publishing society, Web educations, the digital information product of CEK institute encipherment protection has increasing value.The fail safe of CEK just seems even more important like this.
In existing DRM system, the CEK that each digital information product is corresponding fixes.Just there is very large potential safety hazard in this, in case the CEK of this digital information product is cracked this digital information product of the use that so just can put things right once and for all.For example, in Web education, a certain Video tutorials adopts fixation of C EK to encrypt, in case this CEK is cracked so, provides the legitimate rights and interests of the CI of this Video tutorials to be encroached on.And if will change CEK, because some digital information product is real-time or plays online that this will affect user's normal use.
Summary of the invention
For the defective that exists in the above-mentioned prior art, technical problem to be solved by this invention provides a kind of easy replacing, the contents encryption key of the system for numeral copyright management that is difficult for cracking (CEK) changing method.
In order to solve the problems of the technologies described above, the contents encryption key of a kind of system for numeral copyright management provided by the present invention (CEK) changing method, described system for numeral copyright management comprise interconnected content-encrypt layer, mandate/key management layer, flow processing/user interface layer, customer management layer and DRM agency; Wherein, the content-encrypt layer is used for finishing the encryption of programme content, comprises the pre-encryption server of real-time streams encryption server and file; Mandate/key management layer comprises RO administration module, entitlement management module and KMS (Key Management server) module, and entitlement management module comprises copyright real-time release server and the pre-publisher server of copyright; The DRM agency comprises RO administration module, key management module, content decryption module and supervision control module etc.;
It is characterized in that, comprise the CEK switching sequence of real-time streams digital information product and file type digital information product in the CEK changing method;
The CEK switching sequence of described real-time streams digital information product:
1) enter the phase that issues in advance,
Issue (t zero hour phase in advance
PRE), middleware is finished following three work:
Middleware takes out two parts of new CEK from KMS, a KEK by KMS
KMSEncipherment protection, another part protected by real-time streams encryption server public key encryption, and with KEK
KMSThe CEK of protection adds program database;
The pre-publisher server of middleware notice copyright starts pre-issuing process, finishes RO by the pre-issue of rights issuer (RI) to DRM Agent;
Middleware notice real-time streams encryption server key switching instant, and will send to the real-time streams encryption server by the new CEK of encryption server for encrypting protection, make it carry out CEK and switch preparation;
2) enter and issue in advance interim switching phase buffer,
When the RO request of this real-time streams product occurs during this period, new and old CEK should be issued simultaneously; Require middleware switching the starting point notice copyright real-time release server of phase buffer, simultaneously new CEK is delivered to copyright real-time release server;
3) CEK switching instant (t
SWITCH),
The real-time streams encryption server is determined this moment according to the notice of middleware, and constantly starts the CEK switching at this; This occurs among window switching time constantly, switching time window take this constantly as boundary, be divided into front window and rear window; Middleware should be notified this absolute time real-time streams encryption server, the pre-publisher server of copyright and copyright real-time release server.
Further, be provided with a key transitional period in the described CEK switching sequence, the key transitional period starts from before window switching time, ends at after window switching time, formed by front transition and rear transitional period, and also be as boundary take switching instant tSWITCH; The key transitional period is synchronous for the new and old CEK's of realization between real-time streams encryption server and DRM Agent; " key transitional period " changed the strategy configuration by key and delivers to the real-time streams encryption server.
The CEK switching sequence of described file type digital information product:
1) enter the phase that issues in advance,
Issue (t zero hour phase in advance
PRE), middleware takes out two parts of new CEK from KMS, a KEK by the KMS management
KMSEncipherment protection, another part protected by the pre-encryption server public key encryption of file, and with KEK
KMSThe CEK of protection adds program database;
The pre-publisher server of middleware notice copyright starts pre-issuing process;
Middleware will send to the pre-encryption server of file by the new CEK that the pre-encryption server public key encryption of file is protected, and the pre-encryption server of circular document adopts new CEK that file is encrypted, and the CEK switching instant is informed the pre-encryption server of file;
2) issuing in the phase in advance,
The pre-publisher server of copyright is finished RO by the pre-issue of rights issuer (RI) to DRM Agent; The pre-encryption server of file returns the storage address that adopts the file after new CEK encrypts;
3) CEK switching instant (t
SWITCH),
The pre-encryption server of file is determined this moment according to the notice of middleware, and notifies media asset management system at this moment middleware: upgrade this digital information product URL, point to new encrypt file; Middleware should be notified this absolute time the pre-encryption server of file, the pre-publisher server of copyright and copyright real-time release server.
Further, be provided with a key transitional period in the described CEK switching sequence, the key transitional period starts from the new CEK term of validity, ends at the old CEK term of validity, and the key transitional period comprises key switching instant (t
SWITCH).It is in order to guarantee that the client can watch in the following situation as usual that the file type digital information product key transitional period is set: before the key switching instant, use old CEK to start on-demand process, and the process that program request is watched is crossed over switching instant; System Assurance is at the key of file type digital information product in the transitional period, newly, the file encrypted of old CEK and depositing, delete the file that old CEK encrypts after transitional period finishes, this requires the maximum duration that the key transitional period should watch greater than a file type digital information product again." key transitional period " changed the strategy configuration by key and delivers to the pre-encryption server of file.
Utilize contents encryption key (CEK) changing method of system for numeral copyright management provided by the invention, because the CEK switching sequence that adopts the present invention to propose, not impact of result of use on file type digital information product, result of use impact on real-time streams digital information product is very little, is not more than the common TV channel and switches the impact that brings; The more important thing is, by the CEK of regular switching digital information product, and under the emergency situations such as CEK leakage emergency replacement CEK, better protect the copyright of digital information product, ensure the legitimate rights and interests of CI.CEK changing method of the present invention is easily changed CEK, is difficult for cracking.
Description of drawings
Fig. 1 is the structured flowchart of DRM system;
Fig. 2 is the sequential chart that embodiment of the invention real-time streams digital information products C EK switches;
Fig. 3 is that real-time streams digital information products C EK switches TSC implication schematic diagram among the embodiment;
Fig. 4 is the sequential chart that embodiment of the invention file type digital information products C EK switches.
Embodiment
Below in conjunction with description of drawings embodiments of the invention are described in further detail, but present embodiment is not limited to the present invention, every employing similarity method of the present invention and similar variation thereof all should be listed protection scope of the present invention in.
The invention provides a kind of CEK changing method, its core concept be the pre-issue of RO and switching time window.The pre-issue of RO refers to that the RO that rights issuer (RI) will comprise CEK should be published to customer terminal equipment, for the switching of CEK is prepared before CEK switches.Because there is deviation in the clock of each equipment in the system, can't realize the Complete Synchronization of switching instant, therefore window switching time is set, to guarantee that at client device time and server time client device also can normally use the digital information product slightly in the deviation situation.Switching time, window was by front window (T
F_WIN) and rear window (T
L_WIN) form.Switching time, window was unified parameter in the system, unified configuration management by middleware, should not change easily.Publisher server is postponed the deadline of old CEK when generating RO behind the key switching instant, cross over rear window; The zero-time of new CEK is extended before the key switching instant, cross over front window.
As shown in Figure 1, in the contents encryption key of a kind of system for numeral copyright management that the embodiment of the invention provides (CEK) changing method, DRM comprises interconnected content-encrypt layer, mandate/key management layer, flow processing/user interface layer, customer management layer and DRM agency; Wherein, the content-encrypt layer is mainly finished the encryption of programme content, comprises that real-time streams is encrypted and file is encrypted in advance; Mandate/key management layer mainly comprises RO management, empowerment management and KMS; Flow processing/user interface layer mainly comprises operation flow and business model processing and DRM user interface; Customer management layer mainly comprises Customer Tracking and authentication; The DRM agency mainly comprises RO management, key management, contents decryption and supervision control module etc.CEK proposed by the invention switches content decryption module among the real-time streams encryption server that relates in copyright real-time release server and the pre-publisher server of copyright in KMS, the entitlement management module, the content-encrypt layer and the pre-encryption server of file and the DRM agency, relate in addition the middleware of being responsible for coordinating each module work, clearly do not draw among middleware Fig. 1.Certainly the CEK switching might not require DRM such as aforementioned structure, as long as have above-mentioned related module.
The below is divided into real-time streams digital information products C EK switches and two kinds of situations of file type digital information products C EK, how CEK is switched with Fig. 3 in conjunction with Fig. 2 respectively and does in detail explanation.
Fig. 2 is one embodiment of the present of invention, describes real-time streams digital information products C EK switching flow.The digital information product that present embodiment is told about adopts the information flow form transmission of definition among the ITU-T Rec.H.222.0|ISO/IEC 13818, and control bit (transport_scrambling_control, note by abridging be TSC) is encrypted in wherein transmission done as shown in Figure 3 definition.As can be seen from Figure 3: 01 expression data flow is used existing secret key encryption; 10 expressions are in the front transitional period, and data flow is used old secret key encryption; 11 expressions are in the rear transitional period, and data flow adopts new CEK to encrypt.
It is as follows that real-time streams digital information products C EK switches concrete steps:
Step 1) issues t zero hour phase in advance
PRE, middleware takes out two parts of new CEK from KMS, a KEK by the KMS management
KMSEncipherment protection, another part protected by real-time streams encryption server public key encryption; With KEK
KMSThe CEK of protection adds program database; To send to the real-time streams encryption server by real-time streams encryption server public key encryption protection CEK.Middleware notifies the key switching instant to real-time streams encryption server, the pre-publisher server of copyright and copyright real-time release server.Middleware is delivered to new CEK the pre-publisher server of copyright simultaneously issuing in advance the pre-publisher server of starting point notice copyright of phase.Issuing in the phase in advance, the pre-publisher server of copyright is finished RO and is issued in advance, so that DRM Agent has the relevant RO corresponding to new CEK, for key switches ready.
Step 2) middleware is delivered to new CEK copyright real-time release server simultaneously switching the starting point notice copyright real-time release server of phase buffer.When the RO request to real-time streams digital information product occurs in switching phase buffer, new and old CEK should be issued simultaneously.
Step 3) as shown in Figure 2, front zero hour transitional period the real-time streams encryption server TSC is set is 10, the expression key is about to switch, DRM Agent deciphering module detects this control bit, gets ready for key switches; Switch encryption key at key switching instant real-time streams encryption server, begin to adopt new CEK encrypting traffic, and TSC is set is 11, enter the rear transitional period; In rear finish time transitional period, it is 01 that TSC is set, and the expression key switches to be finished.
Because there is deviation in the clock of each equipment in the system, can't realize the Complete Synchronization of switching instant, therefore in Fig. 2, be provided with window switching time, to guarantee that at client device time and server time client device also can normally use real-time streams digital information product slightly in the deviation situation.
Fig. 3 is another one embodiment of the present invention, the CEK switching sequence of description document type digital information product.The digital information product that exists with document form that present embodiment File type digital information product refers to prerecords.The encryption and decryption mode of file type digital information product is different from real-time streams digital information product, and the former adopts the mode of pre-encryption, and the information products after the encryption are stored in the background server end (for DRMAgent) of DRM with the form of file; And the latter adopts while encrypting the formal layout of transmission, and the data flow of encrypting directly sends to DRM Agent.In conjunction with Fig. 3, details are as follows to the switch step of file type digital information products C EK:
Step 1) issues t zero hour phase in advance
PRE, middleware takes out two parts of new CEK from KMS, a KEK by the KMS management
KMSEncipherment protection, another part is by the pre-encryption server public key encryption protection of file; With KEK
KMSThe CEK of protection adds program database; To send to the pre-encryption server of file by the pre-encryption server public key encryption protection of file CEK.Middleware notifies the key switching instant to the pre-encryption server of file, the pre-publisher server of copyright and copyright real-time release server.
Step 2) issuing in the phase in advance, the pre-publisher server of copyright is finished RO and is issued in advance, so that DRM Agent has the relevant RO corresponding to new CEK, for key switches ready; The pre-encryption server of file adopts new CEK that file is encrypted, and returns the storage address that adopts the file after new CEK encrypts.
Step 3) as shown in Figure 4, at key switching instant t
SWITCH, upgrade this digital information product URL, point to new encrypt file.We it can also be seen that from Fig. 4, have crossed key switching instant t
SWITCHAfterwards, old CEK is also effective, and the term of validity continues up to finish time key transitional period, guarantees so still can normally use file type digital information product in key switching instant client.
Step 4) after the end of key transitional period, deletes the file that old CEK encrypts.
In the transitional period, also deposit by the file that new, old CEK encrypts at the key of file type digital information product for System Assurance, with the normal use that guarantees that key switches does not affect file type digital information product.
Claims (4)
1. the content ciphered key exchange method of a system for numeral copyright management, described system for numeral copyright management comprises interconnected content-encrypt layer, mandate/key management layer, flow processing/user interface layer, customer management layer and digital copyright management proxy; Wherein, the content-encrypt layer is used for finishing the encryption of programme content, comprises the pre-encryption server of real-time streams encryption server and file; Mandate/key management layer comprises right objects administration module, entitlement management module and Key Management server, and entitlement management module comprises copyright real-time release server and the pre-publisher server of copyright; Digital copyright management proxy comprises right objects administration module and key management module and content decryption module;
It is characterized in that comprise the contents encryption key switching sequence of real-time streams digital information product in the content ciphered key exchange method, described contents encryption key switching sequence comprises:
1) enter the phase that issues in advance,
Issue zero hour phase in advance, middleware is finished following three work:
Middleware takes out two parts of new contents encryption keys from Key Management server, a key-encrypting key encipherment protection by Key Management server, another part protected by real-time streams encryption server public key encryption, and will add program database by the contents encryption key of key-encrypting key encipherment protection;
The pre-publisher server of middleware notice copyright starts pre-issuing process, finishes right objects by the pre-issue of rights issuer to digital copyright management proxy;
Middleware notice real-time streams encryption server key switching instant, and will send to the real-time streams encryption server by the new contents encryption key of real-time streams encryption server public key encryption protection, make it carry out contents encryption key and switch preparation;
2) enter and issue in advance interim switching phase buffer,
When in switching phase buffer, the right objects request of this real-time streams digital information product occuring, new and old contents encryption key should be issued simultaneously; Require middleware switching the starting point notice copyright real-time release server of phase buffer, simultaneously new contents encryption key is delivered to copyright real-time release server;
3) key switching instant,
The real-time streams encryption server is determined the key switching instant according to the notice of middleware, and starts the key switching at the key switching instant; The key switching instant occurs among window switching time, switching time window take the key switching instant as boundary, be divided into front window and rear window; Middleware should be notified the key switching instant real-time streams encryption server, the pre-publisher server of copyright and copyright real-time release server.
2. content ciphered key exchange method according to claim 1, it is characterized in that, be provided with a key transitional period in the described contents encryption key switching sequence, the key transitional period starts from before window switching time, end at after window switching time, formed by front transition and rear transitional period, and take the key switching instant as boundary; The key transitional period is used for realizing the synchronous of new and old contents encryption key between real-time streams encryption server and digital copyright management proxy; The form that beginning and ending time key transitional period is changed strategy with key sends to the real-time streams encryption server.
3. the content ciphered key exchange method of a system for numeral copyright management, described system for numeral copyright management comprises interconnected content-encrypt layer, mandate/key management layer, flow processing/user interface layer, customer management layer and digital copyright management proxy; Wherein, the content-encrypt layer is used for finishing the encryption of programme content, comprises the pre-encryption server of real-time streams encryption server and file; Mandate/key management layer comprises right objects administration module, entitlement management module and Key Management server, and entitlement management module comprises copyright real-time release server and the pre-publisher server of copyright; Digital copyright management proxy comprises right objects administration module and key management module and content decryption module;
It is characterized in that, the contents encryption key switching sequence of content ciphered key exchange method include file type digital information product, the contents encryption key switching sequence of this document type digital information product comprises:
1) enter the phase that issues in advance,
Issue zero hour phase in advance, middleware takes out two parts of new contents encryption keys from Key Management server, a key-encrypting key encipherment protection by the Key Management server management, another part protected by the pre-encryption server public key encryption of file, and will add program database by the contents encryption key of key-encrypting key encipherment protection;
The pre-publisher server of middleware notice copyright starts pre-issuing process;
Middleware will send to the pre-encryption server of file by the fresh content encryption key of the pre-encryption server public key encryption protection of file, and the pre-encryption server of circular document adopts the fresh content encryption key that file type digital information product is encrypted, and the key switching instant is informed the pre-encryption server of file;
2) issuing in the phase in advance,
The pre-publisher server of copyright is finished right objects by the pre-issue of rights issuer (RI) to digital copyright management proxy; The pre-encryption server of file returns the storage address of the file type digital information product after the employing fresh content encryption keys;
3) key switching instant,
The pre-encryption server of file is determined the key switching instant according to the notice of middleware, and notifies media asset management system at key switching instant middleware: upgrade this digital information product URL, point to new encrypt file; Middleware should be notified the key switching instant the pre-encryption server of file, the pre-publisher server of copyright and copyright real-time release server.
4. content ciphered key exchange method according to claim 3, it is characterized in that, be provided with a key transitional period in the described contents encryption key switching sequence, the key transitional period starts from the fresh content encryption key term of validity time started, end at old contents encryption key term of validity deadline, the key switching instant is positioned at key within the transitional period; The key transitional period should be watched once maximum duration greater than file type digital information product; The form that beginning and ending time key transitional period is changed strategy with key sends to the pre-encryption server of file.
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| CN116319092B (en) * | 2023-05-18 | 2023-08-18 | 北京智芯微电子科技有限公司 | Encryption and decryption method, device and system for data and computer readable storage medium |
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| CN1866266A (en) * | 2005-11-28 | 2006-11-22 | 华为技术有限公司 | Key management method and apparatus for digital copyright management |
| CN1937495A (en) * | 2006-09-29 | 2007-03-28 | 清华大学深圳研究生院 | Digital copyright protection method and system for media network application |
| US20070156590A1 (en) * | 2006-01-03 | 2007-07-05 | Samsung Electronics Co., Ltd. | Method and apparatus for re-importing content |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1866266A (en) * | 2005-11-28 | 2006-11-22 | 华为技术有限公司 | Key management method and apparatus for digital copyright management |
| US20070156590A1 (en) * | 2006-01-03 | 2007-07-05 | Samsung Electronics Co., Ltd. | Method and apparatus for re-importing content |
| CN1937495A (en) * | 2006-09-29 | 2007-03-28 | 清华大学深圳研究生院 | Digital copyright protection method and system for media network application |
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