CN1284818A - Full digital conditioned receiving method for video broadcost in cable TV network - Google Patents
Full digital conditioned receiving method for video broadcost in cable TV network Download PDFInfo
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
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- 238000010586 diagram Methods 0.000 description 6
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Abstract
In the present invention program source is first converted via A/D conversion into moving image code stream, which is scrambled by the control word the control system produces, and the control word is enciphered with enciphered algorithm. The scrambled transmitted stream is then descrambled by the control word, decompressed and decoded to restore digital video and audio signals before final D/A conversion. The present invention has fully digitized processing and transmission process and complete image descrambling without damage and is easy to be accepted by user.
Description
The present invention relates to a kind of digital Conditional Access method that is used for the online video broadcasting of cable TV, belong to communication
Technical field
Along with the development of digital video broadcasting, spectators will be in the face of the selection of more and more comprehensive or special channels, enjoy more high-quality, the program of more services.Video frequency program propagates into almost hard-core geographic range by broadcasting satellite, television network broadcast and cable TV network, and the user that the feeler of these networks touches can watch the program of a TV and Radio Service.The broadcasting dealer will be that then the copyright of these programs buys, and makes and bears higher cost, and the income of simple advertisement is not enough, requires that the user is collected certain license fee and uses.And on the other hand, investigate also explicit user and be ready to prepay certain expense to obtain better services.
Can conditional access system (Conditional Access system) be exactly for commercial object some broadcast service to be implemented access control, determine a digital accepting device specific broadcast program is represented the system to the end user.The Conditional Access specification requirement can make the user freely select to watch program, can protect broadcasting dealer's interests again, guarantees to have only the user who has paid or be about to defrayment just can watch selected TV programme.In digital TV field, conditional access system will become the requirement of the new service of development undoubtedly.
Conditional access system is the system of a more complicated, and it mainly comprises: scrambling part, addressing part, and security system.Scrambling is the important component part of conditional access system, also is simultaneously the operation than bottom.Traditional color TV such as PAL, what adopt among NTSC and the SECAM is analog signal, its scrambling principle mainly is destruction and recovers its level and vertical synchronizing signal.Scrambling can be carried out in the video basic frequency band.Use analog signal method for scrambling cost higher.On the one hand, if the method for scrambling that adopts is very simple, fail safe just can't guarantee, makes and usurps wildness; On the other hand, continuous, complicated simulation method for scrambling can make the scrambling cost improve, because analog signal, the simulation method for scrambling can bring the to a certain degree decline of image quality, especially may make picture quality finally unacceptable under continuous processing.
The objective of the invention is to propose a kind of digital Conditional Access method that is used for the online video broadcasting of cable TV, this method is that digital broadcast television safe and effective, that be easy to promote adds, de-scrambling method, to finish the Conditional Access of radio and television, be beneficial to the toll administration of radio and television.
The present invention proposes is used for the digital Conditional Access method of the online video broadcasting of cable TV, may further comprise the steps:
1. at first the analog video audio signal of program source is carried out analog to digital conversion and generate digital stream, this digital stream compressed encoding is generated basic stream, then a plurality of basic streams are multiplexed into transport stream, to generate motion video and sound accompaniment thereof coding international standard-2 (hereinafter to be referred as MPEG-2) code stream;
2. produced a control word in every several seconds by management system, produce pseudo random sequence, transport stream is carried out xor operation to realize scrambling, produce the scrambling code stream with this pseudo random sequence with this control word control;
3. with the secret keys cryptographic algorithm control word is encrypted, encrypted control word is called Entitlement Control Message (ECM), the business cipher key that the key that cryptographic algorithm adopts provides for management system, the algorithm that the present invention adopts is Data Encryption Standard algorithm (hereinafter to be referred as the DES algorithm);
4. when changing business cipher key, with public key algorithm business cipher key is encrypted, encrypted service key is called Entitlement Management Message (hereinafter to be referred as EMM), the distributing key that the key that public key encryption algorithm adopts provides for management system, the algorithm that the present invention adopts is the RSA public key algorithm;
5. Entitlement Management Message and Entitlement Control Message are placed in the Conditional Access information data section of the program specific information bag (hereinafter to be referred as PSI) in the transport stream, then together program specific information bag and scrambling code stream multiplex;
6. multi-form according to the program stream transmission channel by modulation, goes out the programming after encrypting;
7. after user side is received program after the encryption, from the program specific information bag of the transport stream that receives, isolate Entitlement Management Message and Entitlement Control Message;
8. the distributing key of storing in the smart card that is provided by program provider is decrypted Entitlement Management Message with public key algorithm, obtains business cipher key;
9. then the business cipher key that obtains is decrypted Entitlement Control Message, obtains a control word;
10. produce the pseudo random sequence identical with this control word control at last with transmitting terminal, with this pseudo random sequence the transport stream of scrambling is carried out xor operation, obtain the descrambling transport stream, after transport stream behind the descrambling decompressed, decodes, recover digital video and audio signal, and then carry out digital to analog conversion, can recover optical signal.
Method of the present invention has the following advantages:
1. handling and transmit overall process is digitlization;
2. safe and reliable, the DES algorithm of employing and the probability that RSA Algorithm is broken are minimum;
3. the image descrambling is complete, and the image behind the descrambling is damage not.
4. it is convenient and reliable to add descrambling, adopts pseudo random sequence and transport stream xor operation, convenient and swift;
5. ratio of performance to price height is easy to be accepted by the user.
Description of drawings:
Fig. 1: digital Conditional Access method system block diagram;
Fig. 2: key handling flow chart;
Fig. 3: secret keys algorithm encrypting and deciphering system block diagram;
Fig. 4: triple des encryption and decryption process block diagram
Fig. 5: public key algorithm encrypting and deciphering system block diagram.
Introduce operation principle of the present invention and process in detail below in conjunction with accompanying drawing:
The system block diagram of digital Conditional Access method as shown in Figure 1.
Digital Conditional Access method of the present invention, at first with the video of simulation, audio signal is carried out analog to digital conversion, becomes digital stream; The digital stream data volume that generates is too big, if not compressing processing can't transmit, therefore again this digital stream compressed encoding is become the MPEG-2 code stream on the net, after user side receives, compressed bit stream can be de-compressed into digital stream, carry out digital-to-analogue conversion again, generate the video of simulation, frequently signal.
The key handling flow chart as shown in Figure 2.In the present invention, the scrambling operation is to be finished by the pseudo random sequence of a control word control, and the assailant is only under the prerequisite that obtains control word, just can obtain pseudo random sequence, could be decrypted ciphertext, in order to increase reliability, control word just changed once every several seconds simultaneously.If control word is easy to victim and intercepts and captures with directly transmission on the net of form expressly, can not play the effect of scrambling, therefore must encrypt control word.
The present invention adopts the secret keys cryptographic algorithm that control word is encrypted, the key that adopts in the algorithm is called business cipher key, shown in Figure 3 in the encrypting and deciphering system block diagram of employing secret keys algorithm such as the appendix, encryption key K and decruption key K are same keys among the figure, ciphering process expression formula C=E
K(m), wherein m is a plaintext initial information just, and C is a ciphertext, and K is an encryption key, and E is a cryptographic algorithm, and after cryptographic algorithm E determined, for identical plaintext m, different encryption key K produced different ciphertext C; Decrypting process expression formula m=D
K(C), D is that decipherment algorithm is the inverse process of cryptographic algorithm E.The secret keys cryptographic algorithm that adopts among the present invention is the triple des cryptographic algorithm, common DES algorithm adopts the key of 56 bit long the plain text encryption of 64 bit long to be become the ciphertext of 64 bit long, therefore will decode this algorithm, when adopting the method for exhaustion, be 2 to the volumes of searches of key
56The order of magnitude.The structured flowchart that adopts the triple des algorithm as shown in Figure 4, ciphering process C=E
K1[D
K2[E
K1[m]]] promptly earlier with 1 pair of expressly m encryption of key K, produce ciphertext C1, with 2 pairs of ciphertext C1 deciphering of key K, produce ciphertext C2 again, use 1 couple of ciphertext C2 of key K to encrypt at last, produce ciphertext C; Decrypting process m=D
K1[E
K2[D
K1[C]]], to ciphertext C deciphering, produce ciphertext C3 with K1, with K2 ciphertext C3 is encrypted, produce ciphertext C4, to ciphertext C4 deciphering, finally recover expressly m with K1, owing to adopt dual key mechanism, the key total length is 112bits, when adopting the method for exhaustion, is 2 to the volumes of searches of key
112The order of magnitude has increased the difficulty of decoding greatly.Ciphering process is shown in Fig. 4 (a), with this algorithm control word is encrypted, authorized control information (ECM), be placed on that the transport stream after scrambling sends to user side in the program specific information (PSI) in the transport stream, user side adopts the decrypting process shown in Fig. 4 (b) that Entitlement Control Message is decrypted, and obtains the control word that descrambling is used; Though the disclosed algorithm of DES, but because the reliability of such algorithm, the assailant wants to decode under the prerequisite that can not obtain business cipher key, must pay high cost and cost long time, and business cipher key usually will change once every a period of time, even therefore victim has been decoded, business cipher key is also of no use.
Similarly, business cipher key in this algorithm can not be with directly transmission on the net of form expressly, must after encrypting, just can transmit on the net again, the present invention adopts the RSA Public Key Cryptographic Systems that business cipher key is encrypted, the principle of public key algorithm encryption and decryption and process, as shown in Figure 5, encryption key K1 in this algorithm and decruption key K2 are not same keys, all be called distributing key, K1 is disclosed key, be called public-key cryptography, K2 is the covert private key that the user preserves, be called private cipher key, the fail safe of RSA is based on the following judgement in number theory and the computational complexity: it is easy asking the product of two big prime numbers to calculate, but the long-pending prime factor of obtaining it that decomposes two big prime numbers then is to calculate to go up difficulty, at first select two big prime number p, q makes n=p * q, φ (n)=(p-1) * (q-1), appoint and to get a small integer e and φ (n) is coprime, try to achieve d with division algorithm, make (the mod φ (n)=1 of e * d), (e, n) open as PKI, (d n) maintains secrecy as private key, and ciphering process is for to be decomposed into length less than log with plaintext
2(n) piece calculates
C=E
K1(m)=m
emod?n
Decrypt operation is
m=D
K2(m)=C
d?mod?n
Transmitting terminal is encrypted business cipher key with public-key cryptography and is generated Entitlement Management Message (EMM), be placed in the program specific information in the transport stream with Entitlement Control Message (ECM), transport stream after scrambling sends to user side, user side receives that the back is decrypted Entitlement Management Message with private cipher key, obtain business cipher key, and then Entitlement Control Message is deciphered with business cipher key.The advantage of this algorithm is that distributing key not be used in online transmission, defective is an encryption and decryption process more complicated, need take a long time, but owing to business cipher key normally with hour or day be that unit changes, or change with the difference of program, and Entitlement Management Message is shorter, therefore this algorithm can meet the demands fully, the mode that the user obtains private cipher key is that the service provider regularly offers user's private cipher key with the form of smart card, and not be used in online transmission, thereby avoided the insecurity of online transmission.
By the controlled word in RSA and triple des deciphering back, under the control of this control word, produce the pseudo random sequence identical with transmitting terminal, scrambled code stream is carried out xor operation, obtain the descrambling code stream, this process based on a XOR b again XOR b equal the principle of a.Transport stream behind the descrambling is decompressed, recover digital video and audio signal, carry out digital to analog conversion again, just obtained pictures and sounds.
Claims (1)
1, a kind of digital Conditional Access method of the online video broadcasting of cable TV that is used for is characterized in that this method may further comprise the steps:
1) at first the analog video audio signal of program source is carried out analog to digital conversion and generate digital stream, this digital stream compressed encoding is generated basic stream, then a plurality of basic streams are multiplexed into transport stream, to generate motion video and sound accompaniment thereof coding international standard-2 code stream;
2) produced a control word in every several seconds by management system, produce pseudo random sequence, transport stream is carried out xor operation to realize scrambling, produce the scrambling code stream with this pseudo random sequence with this control word control;
3) with the secret keys cryptographic algorithm control word is encrypted, encrypted control word is called Entitlement Control Message, the business cipher key that the key that cryptographic algorithm adopts provides for management system:
4) when changing business cipher key, with public key algorithm business cipher key is encrypted, encrypted service key is called Entitlement Management Message, the distributing key that the key that public key encryption algorithm adopts provides for management system;
5) Entitlement Management Message and Entitlement Control Message are placed in the Conditional Access information data section of the program specific information bag in the transport stream, then together program specific information bag and scrambling code stream multiplex;
6) multi-form according to the program stream transmission channel by modulation, goes out the programming after encrypting;
7) after user side is received program after the encryption, from the program specific information bag of the transport stream that receives, isolate Entitlement Management Message and Entitlement Control Message;
8) distributing key of storing in the smart card that is provided by program provider is decrypted Entitlement Management Message with public key algorithm, obtains business cipher key;
9) then the business cipher key that obtains is decrypted Entitlement Control Message, obtains a control word;
10) produce the pseudo random sequence identical with this control word control at last with transmitting terminal, with this pseudo random sequence the transport stream of scrambling is carried out xor operation, obtain the descrambling transport stream, after transport stream behind the descrambling decompressed, decodes, recover digital video and audio signal, and then carry out digital to analog conversion, promptly revert to optical signal.
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| CN 00124981 CN1284818A (en) | 2000-09-29 | 2000-09-29 | Full digital conditioned receiving method for video broadcost in cable TV network |
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| CN 00124981 CN1284818A (en) | 2000-09-29 | 2000-09-29 | Full digital conditioned receiving method for video broadcost in cable TV network |
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Cited By (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1299506C (en) * | 2003-08-20 | 2007-02-07 | 王耀 | Condition reception assembled controlling method without addressing authorization |
| CN100346648C (en) * | 2004-01-13 | 2007-10-31 | 北京中视联数字***有限公司 | General user management system for digital television set and interface communication method of authorization management system |
| CN100372379C (en) * | 2002-03-19 | 2008-02-27 | Nxp股份有限公司 | Conditional access control |
| CN100380966C (en) * | 2002-03-20 | 2008-04-09 | 松下电器产业株式会社 | Content playback apparatus, method, and program, and key management apparatus and system |
| CN100388790C (en) * | 2005-09-01 | 2008-05-14 | 南京信风软件有限公司 | Rapid holographic code/decode method |
| CN100394794C (en) * | 2004-03-15 | 2008-06-11 | 北京握奇数据***有限公司 | A method for automatic charging of cable TV |
| WO2008077303A1 (en) * | 2006-12-25 | 2008-07-03 | Beijing Watch Data System Co., Ltd. | A method and system for processing broadcast signal and a receiving terminal of broadcast signal |
| CN100454973C (en) * | 2003-06-13 | 2009-01-21 | 佳能株式会社 | Image capture apparatus |
| CN100481932C (en) * | 2002-07-24 | 2009-04-22 | 纳格拉卡德股份有限公司 | Process and electronic module for secured data transmission |
| CN100518280C (en) * | 2006-04-28 | 2009-07-22 | 中国科学院计算技术研究所 | Video encrypting/deciphering device and encrypting/deciphering method |
| CN101009549B (en) * | 2006-01-26 | 2010-07-14 | 中国科学院计算技术研究所 | Decoding device for the digital copyright management |
| CN101132408B (en) * | 2007-08-16 | 2010-07-21 | 华为技术有限公司 | Stream media content processing method, equipment and system |
| CN1845599B (en) * | 2006-05-17 | 2010-09-01 | ***通信集团公司 | Method for obtaining and updating service key in mobile television service |
| CN101409820B (en) * | 2007-10-09 | 2010-10-06 | 北京视博数字电视科技有限公司 | System and method for tracking user smart card |
| CN101409821B (en) * | 2007-10-09 | 2010-10-20 | 北京视博数字电视科技有限公司 | System and method for tracking user smart card |
| CN101409822B (en) * | 2007-10-09 | 2010-10-20 | 北京视博数字电视科技有限公司 | System and method for tracking user smart card |
| CN101166259B (en) * | 2006-10-16 | 2010-11-10 | 华为技术有限公司 | Mobile phone TV service protection method, system, mobile phone TV server and terminal |
| CN1722659B (en) * | 2004-07-13 | 2011-02-23 | 耶德托存取公司 | Method and system for processing multiplex data and method and system for decoding multiplex data flow |
| CN101272474B (en) * | 2007-03-23 | 2011-03-09 | 北京东方广视科技股份有限公司 | Method for fast switching channels |
| CN1980380B (en) * | 2005-12-05 | 2011-04-27 | 厦门雅迅网络股份有限公司 | Vehicle networked video advertisement agent authorization electronic processing method and system |
| CN101646060B (en) * | 2009-09-04 | 2011-06-22 | 四川虹微技术有限公司 | Protecting method of data content in storage device |
| CN107181563A (en) * | 2016-03-11 | 2017-09-19 | 富士施乐株式会社 | Decoding apparatus, the information transmission system and coding/decoding method |
| CN107547946A (en) * | 2016-06-29 | 2018-01-05 | 伊秘欧波兰有限公司 | Pay television system security enhancement method based on mandatory periodically multiplexed communications |
| CN111277802A (en) * | 2020-03-03 | 2020-06-12 | 浙江宇视科技有限公司 | Video code stream processing method, device, equipment and storage medium |
| CN113179425A (en) * | 2020-11-16 | 2021-07-27 | 北京路安世纪文化发展有限公司 | High-speed digital television signal transmission method |
| CN113630426A (en) * | 2021-10-12 | 2021-11-09 | 广州市保伦电子有限公司 | Private encryption method and system based on simultaneous interpretation |
-
2000
- 2000-09-29 CN CN 00124981 patent/CN1284818A/en active Pending
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| CN100372379C (en) * | 2002-03-19 | 2008-02-27 | Nxp股份有限公司 | Conditional access control |
| CN100380966C (en) * | 2002-03-20 | 2008-04-09 | 松下电器产业株式会社 | Content playback apparatus, method, and program, and key management apparatus and system |
| CN100481932C (en) * | 2002-07-24 | 2009-04-22 | 纳格拉卡德股份有限公司 | Process and electronic module for secured data transmission |
| CN100454973C (en) * | 2003-06-13 | 2009-01-21 | 佳能株式会社 | Image capture apparatus |
| CN1299506C (en) * | 2003-08-20 | 2007-02-07 | 王耀 | Condition reception assembled controlling method without addressing authorization |
| CN100346648C (en) * | 2004-01-13 | 2007-10-31 | 北京中视联数字***有限公司 | General user management system for digital television set and interface communication method of authorization management system |
| CN100394794C (en) * | 2004-03-15 | 2008-06-11 | 北京握奇数据***有限公司 | A method for automatic charging of cable TV |
| CN1722659B (en) * | 2004-07-13 | 2011-02-23 | 耶德托存取公司 | Method and system for processing multiplex data and method and system for decoding multiplex data flow |
| CN100388790C (en) * | 2005-09-01 | 2008-05-14 | 南京信风软件有限公司 | Rapid holographic code/decode method |
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| CN101009549B (en) * | 2006-01-26 | 2010-07-14 | 中国科学院计算技术研究所 | Decoding device for the digital copyright management |
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| CN1845599B (en) * | 2006-05-17 | 2010-09-01 | ***通信集团公司 | Method for obtaining and updating service key in mobile television service |
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| CN101409822B (en) * | 2007-10-09 | 2010-10-20 | 北京视博数字电视科技有限公司 | System and method for tracking user smart card |
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| CN101409820B (en) * | 2007-10-09 | 2010-10-06 | 北京视博数字电视科技有限公司 | System and method for tracking user smart card |
| CN101646060B (en) * | 2009-09-04 | 2011-06-22 | 四川虹微技术有限公司 | Protecting method of data content in storage device |
| CN107181563B (en) * | 2016-03-11 | 2021-03-30 | 富士施乐株式会社 | Decoding device, information transmission system, and decoding method |
| CN107181563A (en) * | 2016-03-11 | 2017-09-19 | 富士施乐株式会社 | Decoding apparatus, the information transmission system and coding/decoding method |
| CN107547946A (en) * | 2016-06-29 | 2018-01-05 | 伊秘欧波兰有限公司 | Pay television system security enhancement method based on mandatory periodically multiplexed communications |
| CN111277802A (en) * | 2020-03-03 | 2020-06-12 | 浙江宇视科技有限公司 | Video code stream processing method, device, equipment and storage medium |
| CN111277802B (en) * | 2020-03-03 | 2021-09-14 | 浙江宇视科技有限公司 | Video code stream processing method, device, equipment and storage medium |
| CN113179425A (en) * | 2020-11-16 | 2021-07-27 | 北京路安世纪文化发展有限公司 | High-speed digital television signal transmission method |
| CN113630426A (en) * | 2021-10-12 | 2021-11-09 | 广州市保伦电子有限公司 | Private encryption method and system based on simultaneous interpretation |
| CN113630426B (en) * | 2021-10-12 | 2022-03-08 | 广州市保伦电子有限公司 | Private encryption method and system based on simultaneous interpretation |
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