ITU-R BT 1852-2009 Conditional-access systems for digital broadcasting《数字广播的条件接入系统》.pdf

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1、 Recommendation ITU-R BT.1852(09/2009)Conditional-access systemsfor digital broadcastingBT SeriesBroadcasting services(television)ii Rec. ITU-R BT.1852 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectru

2、m by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Co

3、nferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statement

4、s and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also avail

5、able online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite

6、services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals an

7、d frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2009 ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means

8、whatsoever, without written permission of ITU. Rec. ITU-R BT.1852 1 RECOMMENDATION ITU-R BT.1852 Conditional-access systems for digital broadcasting (Question ITU-R 49/6) (2009) Scope This Recommendation describes principles intended to facilitate the development of effective conditional-access meth

9、ods for digital broadcasting that uses MPEG-2 transport streams. It provides information on reliable protection of broadcasting services from unauthorized access. The ITU-R Radiocommunication Assembly, considering a) that there is a growing demand in many countries to protect broadcast programmes ag

10、ainst unauthorized reception; b) that an efficient way of ensuring such protection of MPEG-2 transport stream packets, multiplexed according to ITU-T Recommendation H.222.0, is to implement conditional-access broadcasting systems; c) that examples of conditional-access systems have been designed and

11、 are operated for digital terrestrial, digital cable, digital satellite and IP (Internet Protocol) television, as well as sound, multimedia and data services; d) that there are many cases of implementing digital broadcasting systems based on relevant BT and BO Series Recommendations, such as Recomme

12、ndation ITU-R BO.1516 for satellite digital broadcasting systems; e) that it is desirable to limit the number of different conditional-access systems, while taking into account the different requirements of various broadcast services and transmission systems; f) that putting as many common elements

13、of conditional access as possible into the receivers at the outset would give the greatest potential to the general public to access protected services at a reduced equipment cost; g) that conditional access systems provide a protection against and that copyright owners, programme suppliers and serv

14、ice providers desire highly secured broadcast/distribution networks to allow protection of their programmes through access control, recommends 1 that conditional-access systems for digital broadcasting services protecting MPEG-2 transport stream packets should: provide the services available to auth

15、orized receivers only; share the largest number of common elements in the receiver; and be designed according to the fundamental principles listed in Annex 1. NOTE 1 Examples of implementations of conditional-access systems for digital broadcasting are given in Appendix 1. 2 Rec. ITU-R BT.1852 Annex

16、 1 Fundamental principles for the design of conditional-access systems for digital broadcasting 1 Introduction The principles described in this Annex should facilitate the development of effective conditional-access systems for ITU-T Recommendation H.222.0 transport stream (MPEG-2 transport stream)

17、based digital broadcasting that are convenient for both subscribers and service providers, assuring reliable protection of information from unauthorized access. The principles apply generally to the delivery of digital television services, sound services as well as multimedia and data broadcasting s

18、ervices. These principles apply to ITU-T Recommendation H.220.0 transport stream packet delivery to consumers over different media, such as digital terrestrial, digital cable, digital satellite and IP (Internet Protocol) broadcasting. 2 References 2.1 Normative references ITU-T Recommendation H.222.

19、0: Information technology Generic coding of moving pictures and associated audio information: Systems 2.2 Informative references Recommendation ITU-R BT.810: Conditional-access broadcasting systems ARIB STD-B25: Conditional access system specifications for digital broadcasting IEC 62455: Internet pr

20、otocol (IP) and transport stream (TS) based service access. 3 Terms, definitions and abbreviations 3.1 Terms and definitions Scrambling in digital broadcasting Cipher encoding of broadcast content including vision/sound/data in order to prevent unauthorized reception of the information in non-encryp

21、ted format. This cipher encoding is a specified process under the control of the conditional-access system (sending end). Descrambling in digital broadcasting Cipher decoding of broadcast content including vision/sound/data in order to allow reception of the information in non-encrypted format. This

22、 cipher decoding is a specified process under the control of the conditional-access system (receiving end). Conditional access A user accesses a protected service by interacting via conditional-access functionality in the receiver. If, in the session, all the access conditions are met, authorization

23、 occurs, the cipher decoding key is released, and the content is recovered. Subscriber authentication, account confirmation, and validation of service availability or other programme control parameters activate the session encryption/decryption key to let the session conclude the authorization proce

24、ss. Rec. ITU-R BT.1852 3 Conditional-access control The function of the conditional-access control at the sending end is to generate the scrambling control information and the encryption “keys” associated with the service. The function of the conditional-access control at the receiving end is to pro

25、duce the descrambling control information in conjunction with the “keys” associated with the service. Encryption and decryption These are terms used for methods which are used to protect (and interpret) some of the information within the “access-related messages” which have to be transmitted from th

26、e sending end to the receiving end of the conditional-access control functions. Point of origination This is the point in a distribution system where programme or other content first becomes a signal in its final broadcasting/distribution format. It marks the start of end-to-end protection. Entry co

27、ntent may be any form, not necessarily a humanly sensible form. The content input need not itself be intelligible. NOTE 1 The copyright owners, service providers, and distributors form a huge hierarchy of many possible points of origination in a flow of information to a consumer and thus in the flow

28、 of scrambled content and encrypted keys to a consumer. The point of origination ought to begin with a copyright holder or producer. In practice, most points of origination will be simply the points of entry wherever they may be in the system for business and operational reasons. While there may be

29、many such points of entry, each is a unique and independent point from which the information can be consistently maintained in whatever format it may be input all the way through to a consumer. Point of presentation This is the point where programme or other content last occurs as a signal in a dist

30、ribution system before it exists in a humanly sensible form at the receivers screen and speakers. It marks the output from protection. Content This is any form of digital data that can be acquired and presented by a device. Service This is one or more data flows intended to be presented together. Se

31、rvice protection This is protection of a service such that only authorized devices are able to receive and decode it. 3.2 Abbreviations Ks Scrambling key Kw Work key Km Master key EMM Entitlement management message ECM Entitlement control message CRC Cyclic redundancy check DES Data encryption stand

32、ard 4 Rec. ITU-R BT.1852 4 General description of a conditional-access system There are two fundamental functions that comprise conditional-access systems for digital broadcasting; scrambling and access control. They are distinct, and in many cases independent, components in a conditional-access sys

33、tem, each of which is a distinct information process. 4.1 Reference model Conditional access requires that the information be scrambled before it is broadcast. This process is obtained by using cipher encoding to broadcast bit-stream. The descrambling process at the receiving end requires the same c

34、ipher decoding (in this case the descrambling procedure) to recover the original bit-stream. To provide this sequence and to ensure synchronism between the sending and receiving processes, the cipher decoding conditions are controlled by a data transmitted from the cipher encoder to decoder accordin

35、g to special protocol. The detailed structure of this process is given in Fig. 1. FIGURE 1 An example of block diagram of a conditional-access system for digital broadcasting 1852-01ScramblerEncrypterEncrypterDescramblerDecrypterDecrypterMaster keyWork key Access control moduleSending end Receiving

36、endEntitlement control messageEntitlement management messageControl informationViewing judgmentMaster keyScrambling key Work keyService componentScrambling key Control parametersScrambling of video, sound and multimedia and data using cipher encoder Scrambled servicecomponentRec. ITU-R BT.1852 5 4.2

37、 Scrambling This is the process of protecting some or all components of a service to cope with unauthorized accesses by using cipher encoding under the control of the conditional-access system at the sending end. 4.3 Access control This is a provision of information to enable authorized users to des

38、cramble the protected service. The availability of this information is controlled by the conditional-access system. Between the transmitter and the receiver(s), this information is structured in special messages, which may be multiplexed within the broadcast bit-stream itself, or may be delivered by

39、 some other means, such as over a telecommunication line. At the receiving end(s), these messages are interpreted by the access-control system in order to control the descrambling of the authorized parts from received bit-stream in the authorized receiver(s). 5 User requirements 5.1 Anti-hacking str

40、ength of a cipher for scrambler and descrambler A cipher used in scrambler and descrambler blocks should be well tested for anti-hacking capability. A cipher selected from international standards is recommended. 5.2 Security The security of a system is the degree of difficulty encountered by an unau

41、thorized user in attempting to gain access to the protected service. Descrambling the signal without reference to the access control process. This is a function of the nature of the services and the scrambling method. Future television, sound and data broadcasting services are likely to be predomina

42、ntly digital in nature and thus will allow for highly secure scrambling processes. Obtaining the access control key in an unauthorized manner. This is a function of the security of the key encryption algorithms. 5.3 Selection of common or private scrambling algorithm Access is made available, to any

43、 authorized user meeting the conditions for access, via a common (universal) or private scrambling algorithm. The use of a common scrambling algorithm implies that descrambling would be common to all receivers, based on a standard scrambling algorithm, independent to delivery media used, permits low

44、er cost and flexible equipment and would still allow competition through service-provider-specific implementations. The use of private scrambling algorithm implies that the descrambling process would be carried out on the receivers with specific algorithm implemented only. 5.4 Access modes A conditi

45、onal-access system may support a range of access modes, for example: period availability (subscription of the service) authorization runs from a starting time to a finishing time; 6 Rec. ITU-R BT.1852 programme or service item (purchase of an event) availability is for a specific service item, wheth

46、er or not it is completely used; service charge (token based) the charge or use of credit is proportional to the duration of use and/or the value of the service involved; free-to-air service is protected, but the access is provided free of charge. The access modes need to be variable with respect to

47、 several parameters, for example: time; various segments of the service; groups of intended users. 5.5 Equipment standardization To provide maximum economy of manufacturing scale for receiving equipment and to simplify management and maintenance: common equipment should be standardized so that it ca

48、n cater for as many service options as possible; A consumers receiver architecture is required to support the conditional access functionality requirements of the selected conditional access system. Depending on the selected system, the functionality may require support such as embedded or detachabl

49、e security functionality (e.g. smart card). 5.6 Access management The definition of conditional access is based on the formal concept of entitlement to access, which can be implemented in various forms. An entitlement gives to its holder an authorization to access the related service. Uneconomic use of the resources due to management or transmission overheads should be avoided. 5.7 Avoidance of interruptions to the service Interruptions due to faulty or unreliable acquisition of the access control data should be avoided. 6 Entitlement control mes