CN1946018B - Encrypting and de-encrypting method for medium flow - Google Patents
Encrypting and de-encrypting method for medium flow Download PDFInfo
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- CN1946018B CN1946018B CN2006101503287A CN200610150328A CN1946018B CN 1946018 B CN1946018 B CN 1946018B CN 2006101503287 A CN2006101503287 A CN 2006101503287A CN 200610150328 A CN200610150328 A CN 200610150328A CN 1946018 B CN1946018 B CN 1946018B
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Abstract
This invention relates to a ciphering and deciphering method of media flows, in which, the ciphering method includes: a media flow sending party sets up a basic cryptographic key, a package cryptographic key and a dynamic cryptographic key to generate a data ciphered key and cipher the sent media flow to generate ciphered media flow, utilizing the package key to cipher the dynamic key and insert it in the ciphered media flow. The deciphering method includes: the media flow receiving party receives the basic key and the package key from the media flow transmission party and strips off the ciphered dynamic key from the media flow and utilizes the received package key to decipher the ciphered dynamic key to get the dynamic key to generate data ciphered key and utilizes the generated data ciphered key to decipher the received ciphered media flow.
Description
Technical field
The present invention relates to the Network Communicate Security technical field, relate in particular to the encryption transmission and the decryption method of Media Stream.
Background technology
Along with wired and increase wireless network bandwidth, access conditions constantly improves, and is that the Streaming Media of representative is used extensive day by day with audio frequency, video playback.Be the possessory rights and interests of protecting intellectual property rights, media flow security transmission and even the problems such as rights of using control relevant with safe transmission during Streaming Media is used become one of focus gradually.
At present, standard, agreement and the standard of each main audio/video flow transmission to having in this respect relate to more.For example the ISO13818 of International Standards Organization " universal coding of information technology---moving image and audio signal thereof " series standard when describing transport stream in its first, has just been reserved the mechanism that condition inserts.At the beginning of 2004, this standard has increased the tenth part " intellectual property right management of MPEG2 and protection " again newly, so that provide framework and interface for other intellectual property right management and guard method.The 13 part of another of International Standards Organization part audio frequency and video series standard ISO14496 " information technology---audio frequency and video object coding " has also defined " intellectual property right management and protection expansion ".And for example, internet stream media alliance (Internet Streaming Media Alliance ISMA) has also issued encryption and authentication specifications when formulating Streaming Media transmission related specifications, the encryption equipment that meets ISMA standard Media Stream has been manufactured definition.But above-mentioned standard, agreement and standard mainly lay particular emphasis on the frame structure that definition one cover possesses interoperability, and for the concrete grammar of media flow security transmission and use control, it is limited to touch upon.
A kind of change key media stream privacy method is arranged in the prior art, this method is done secure hash to the label in basic key and the media stream data bag, obtain the encryption key of individual data bag, because the label difference of packet, so the encryption key of different pieces of information bag is also different.Also have a kind of double-deck anti-copy method of encrypting in the prior art, its ground floor adopts single key handling, can adopt the encryption method of moderate strength to encrypt pending content; Its second layer is then handled at the key of preceding one deck, can adopt such as higher-strength methods such as asymmetric encryption aforementioned key is handled.Though said method provides some useful thinkings to the encrypted transmission of Media Stream, but still comes with some shortcomings.For example, if owing to the reason part media content of chance is cracked, if the anti-copy method that only adopts above-mentioned bilayer to encrypt, then whole Media Stream all can be cracked.And above-mentioned change key media stream privacy method, because variable-key, though may avoid above-mentioned situation, owing to the packet tag entry as key part raw material is streamed with medium with form expressly, secure context still faces certain risk.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of encryption and decryption method of Media Stream, under the prerequisite that guarantees treatment effeciency, improves the fail safe of media flow transmission, and can be applicable to multiple media flow transmission form and application scenario neatly.
For realizing purpose of the present invention, the invention provides a kind of encryption method of Media Stream, comprise the steps:
(1) Media Stream transmit leg structure foundation key, package key;
(2) Media Stream transmit leg structure dynamic key, and, generate data encryption key according to this dynamic key and described foundation key; The mode that the Media Stream transmit leg takes not timing to change or packet-by-packet change is changed described dynamic key;
(3) the Media Stream transmit leg utilizes described data encryption key that the Media Stream that sends is encrypted, and generates encrypted media streams;
(4) the Media Stream transmit leg utilizes described package key that described dynamic key is encrypted, and generates to encrypt dynamic key, and should encrypt dynamic key and insert in the described encrypted media streams.
In the above-mentioned steps (1), described package key can be identical with foundation key, according to application scenarios, can simplify for two and merge into a unified static keys.
In the above-mentioned steps (4), the Media Stream transmit leg can be inserted in the packet header or inclusion of encrypted media streams encrypting dynamic key; Or in described encrypted media streams, insert new bag and deposit and encrypt dynamic key.Can insert when dynamic key changes the opportunity of inserting, or insert at the critical packet place of encrypted media streams, or all insert at each packet.Described critical packet comprises the packet of random access, the initial data packets of key frame.The available point of encryption dynamic key that inserts Media Stream is for to begin effectively from current data packet, or begins effectively from certain follow-up packet.
For realizing purpose of the present invention, the present invention also provides a kind of decryption method of Media Stream, comprises the steps:
(1) the Media Stream recipient receives foundation key and package key from the Media Stream transmit leg;
(2) the Media Stream recipient separates from the encrypted media streams that receives and encrypts dynamic key, and utilizes the package key receive that this has been encrypted dynamic key to be decrypted, to obtain dynamic key; The mode that the Media Stream transmit leg takes not timing to change or packet-by-packet change is changed described dynamic key;
(3) the Media Stream recipient utilizes the foundation key that receives and deciphers the dynamic key that obtains, and generates data encryption key;
(4) the Media Stream recipient utilizes the data encryption key of generation that the encrypted media streams that receives is decrypted.
In the above-mentioned steps (1), the Media Stream transmit leg passes through the method for safety jointly with described foundation key and package key, or respectively by the method for safety, sends to the Media Stream recipient.
Described method by safety transmits, and is the PKI that utilizes the Media Stream recipient, and foundation key and/or package key are handled and transmitted; And/or utilize the private key of Streaming Media transmit leg, the message that comprises foundation key and/or package key is carried out digital signature handle and transmit.
Compared with prior art, the present invention proposes a kind of media stream privacy of changeable key flexibly method.Current Streaming Media application, on the one hand the safe transmission to Media Stream requires to improve day by day, on the other hand, and transport stream of a great variety, the performance difference of receiving terminal is very big.Method of the present invention, under the prerequisite that guarantees treatment effeciency, the fail safe that has improved media flow transmission, and can be applicable to multiple media flow transmission form and application scenario neatly, for the demand that solves above-mentioned two aspects simultaneously provides a valid approach.
Description of drawings
Fig. 1 is the schematic diagram that the Media Stream transmit leg is encrypted
Fig. 2 is the schematic diagram of Media Stream recipient deciphering
Fig. 3 is the schematic diagram that the present invention is applied in an example in the Web TV field of adopting the Digital Right Management technology
Embodiment
The method that the present invention proposes is the final media stream data encryption key of raw material structure with the dynamic key of metastable foundation key and variation flexibly.On cipher key delivery, foundation key adopts the encryption of higher-strength, and the transfer approach by safety is obtained by the Media Stream recipient, and dynamic key is also encrypted the back by security mechanism and transmitted with Media Stream.Having encrypted dynamic key can be in many ways, add Media Stream opportunity, can adapt to the demand of different application scene.
For the Media Stream transmit leg, ciphering process is as follows:
(A1) Media Stream transmit leg structure foundation key, package key.
(A2) Media Stream transmit leg structure dynamic key, and, generate data encryption key according to the foundation key of constructing in this dynamic key and the step (A1).
(A3) the Media Stream transmit leg utilizes the data encryption key that generates in the step (A2) that the Media Stream that sends is encrypted.
(A4) the Media Stream transmit leg utilizes the package key of structure in the step (A1) that the dynamic key of structure in the step (A2) is encrypted, and the Media Stream that sends in the inserting step as a result (A3) after will encrypting.
For the Media Stream recipient, decrypting process is as follows:
(B1) the Media Stream recipient obtains foundation key, package key.
(B2) the Media Stream recipient separates from the encrypted media streams that receives and encrypts dynamic key.And utilize the package key that obtains in the step (B1) that this has been encrypted dynamic key to be decrypted, to obtain dynamic key.
(B3) the Media Stream recipient utilizes the dynamic key that obtains in the foundation key that obtains in the step (B1) and the step (B2), generates data encryption key.
(B4) the Media Stream recipient utilizes the data encryption key that obtains in the step (B3) that the encrypted media streams that receives is decrypted.
Below in conjunction with accompanying drawing encryption method of the present invention is elaborated.
As shown in Figure 1, the flow process of Media Stream transmit leg encryption of the present invention is as follows:
The Media Stream transmit leg at first obtains foundation key 191 and package key 192.The preparation method of foundation key 191 and/or package key 192 comprises from key management system and obtaining or by the generation of key generation unit etc.Policy control unit 131 is determined to have encrypted the structure of dynamic key and other additional informations and is inserted strategy 136 according to being provided with.
Dynamic key generation unit 111 according to the automatic or manual triggering of the condition that is provided with, generates new dynamic key 116.Dynamic key 116 produces data encryption key 126 at data encryption key generation unit 121 according to the data encryption key generating algorithm with foundation key 191.Wherein, the data encryption key generating algorithm both can adopt disclosed general-purpose algorithm, also can adopt the privately owned mode of oneself.For example, adopt the KDF2 algorithm in the X9.44 standard to generate key.Dynamic key 116 carries out cryptographic calculation with package key 192 at dynamic key ciphering unit 122, has been encrypted dynamic key 127.Wherein the dynamic key cryptographic algorithm equally both can adopt disclosed general-purpose algorithm, also can adopt the privately owned mode of oneself.For example, adopt aes algorithm to utilize package key that dynamic key is encrypted.
Original media stream is inserted unit 103 by packet resolution unit 101, packet ciphering unit 102, information successively, obtains encrypted media streams.Wherein the packet resolution unit 101, mainly judge the characteristic information 106 of current data packet, and for example, what comprise in the packet is media data or control information, and whether packet is first packet of key frame etc.The packet characteristic information that packet resolution unit 101 obtains is sent to packet ciphering unit 102, and whether packet ciphering unit 102 is encrypted current data packet according to packet characteristic information and control strategy 136 decisions.Encrypt if desired, confirm further that then adopting the current key of depositing still is up-to-date data encryption key 126, and in view of the above packet is encrypted.Whether information is inserted unit 103 will encrypt dynamic key 127 insertion Media Streams according to packet characteristic information and control strategy 136 decisions.Insert if desired, then further confirm the methods of insertion, and will encrypt dynamic key 127 and other additional informations that may need insertion Media Stream in view of the above.Wherein, other additional informations that may need comprise part control strategy (for example inserting the available point of encrypting dynamic key of Media Stream) etc.
What need supplementary notes is that foregoing strategy comprises encrypts the mode that dynamic key inserts Media Stream, has encrypted the opportunity that dynamic key inserts Media Stream, inserts the available point of encrypting dynamic key of Media Stream etc.Wherein encrypted mode that dynamic key inserts Media Stream and can comprise and add extended field, has added new bag extremely between original media stream data bag etc. to media stream data packet header; Encrypted and can comprise when dynamic key changes and inserting that the critical packet place inserts on opportunity that dynamic key inserts Media Stream, each packet all inserts etc.; The available point of encrypting dynamic key that inserts Media Stream can comprise from current data packet and beginning effectively, begins effective etc. from certain follow-up packet.The selection of strategy is decided according to concrete application scenarios, for example, the Media Stream of Chu Liing is the MPEG2-TS form that defines in the ISO13818 standard first if desired, because this form is the fixed-length data bag, the mode of then having encrypted dynamic key insertion Media Stream should be to add new bag between original media stream data bag; The Media Stream of Chu Liing is the form of ISMA normalized definition if desired, though having encrypted the mode of dynamic key insertion Media Stream both can be by having increased header field, also can be by increasing extra bag, but for ISMA encrypt with authentication specifications in the mechanism that defines be complementary, mainly adopt the method that increases header field to insert to have encrypted dynamic key.And for example, if Media Stream recipient's disposal ability a little less than, the dynamic key of encryption that transmits with packet is if come into force, might cause the of short duration stagnation of broadcasts such as audio frequency and video, in the selection of the available point of encrypting dynamic key that inserts Media Stream, just can be set to begin effectively like this from follow-up one or several packets.For another example, during audio/video flow transmits, the Media Stream transmit leg is supported operations such as F.F., rewind down, time shift if desired, be guaranteed efficiency, the replacing of dynamic key is preferably only carried out when handling the critical packet that key frame data bag etc. can random access, has encrypted then should be chosen as the critical packet place opportunity that dynamic key inserts Media Stream.
As shown in Figure 2, a kind of flow process of Media Stream recipient deciphering of the present invention is as follows:
The Media Stream recipient at first obtains package key 291 and foundation key 292.Encrypted media streams at first is sent to packet resolution unit 201, and packet resolution unit 201 therefrom extracts packet characteristic information 206.202 of information extraction unit are according to packet characteristic information 206, and judging whether need information extraction from the media stream data bag that resolution unit 201 transmits.If desired, then extract and encrypted dynamic key 207 and/or control strategy 208.Encrypt dynamic key 207 and sent into dynamic key decrypting device 211 immediately, utilized package key 291 to solve dynamic key.This dynamic key is admitted to data encryption key generation unit 221 then, obtains data encryption key 226 with the foundation key acting in conjunction.Packet decrypting device 203 judges whether the media stream data bag that needs deciphering to transmit from information extraction unit 202 according to packet characteristic information 206 and control strategy 208.If desired, then utilize data encryption key 226 that it is decrypted, finally obtain decrypt media stream.
What need supplementary notes is, Media Stream recipient's dynamic key decrypting device 211, and it adopts the algorithm must be corresponding with the dynamic key ciphering unit 122 of Media Stream transmit leg; Media Stream recipient's data encryption key generation unit 221, it adopts algorithm data encryption key generation unit 121 necessary and the Media Stream transmit leg in full accord.And the control strategy 208 that the Media Stream recipient is extracted then is a subclass of Media Stream transmit leg control strategy 136, and other can't be by the control strategy of Media Stream acquisition, and the Media Stream recipient can adopt the mode of agreement to preset and finish.
As shown in Figure 3, in Web TV (IPTV) field of adopting Digital Right Management (DRM) technology, a kind of specific embodiment of the present invention is as follows:
When certain channel in the network television system need adopt the Digital Right Management technology to protect, OSS 309 can send channel to media stream privacy center 306 and encrypt request 311.For simplifying key management, in the present embodiment, media stream privacy center 306 is a static keys with package key and foundation key unification.After media stream privacy center 306 receives channel encryption request 311, static keys of pre-generation, and to KMC's 307 transmission key registration and inquiry requests 312, whether this channel can at first be inquired about by KMC 307 static keys, if existing static keys is then returned Query Result in key registration and inquiry response 313; Otherwise, the pre-generation key that then carries in the register request message 312, and in response message 313, comprise this key.A kind of exception is that if channel key is requirement pressure renewal, then inquiry will no longer be done by KMC, directly upgrade registration data.Static keys is wherein kept in media stream privacy center 306 after receiving key registration and inquiry response 313, and replys OSS 309 channel encrypted responses 314.OSS 309 can transmit service system 305 beginning channels encryptions by the notification streams medium after receiving this response.Streaming Media transmits service system 305 and sends original media stream 321 to media stream privacy center 306, and receives the encrypted media streams 322 after its processing.The ciphering process of the 306 pairs of Media Streams in media stream privacy center can be described with reference to the flow process among the figure 1.
When the user uses set-top box 301, after the 309 channel subscription requests 351 of electronic program list notice OSS, OSS can require authorization center 308 structure authorization objects, and the content of authorization object comprises that the user watches the authorization limitations could information of channel, the static keys of channel etc.Wherein authorization limitations could information can directly obtain from authorization object structure request 352, and static keys then needs to obtain to KMC's 307 inquiries by key query requests 353.The static keys of taking back in the key inquiry response 354 need just can be inserted in the authorization object by handling, and for example, utilizes the PKI of set-top box 351 that this static keys is carried out the asymmetric encryption processing.After having constructed authorization object, authorization center is replied authorization object tectonic response 355 message and is given OSS 309, and OSS sends channel subscription response 356 subsequently to set-top box 301.Wherein channel subscription response 356 has comprised the information that set-top box is obtained authorization object that triggers.After set-top box 301 receives this trigger message, obtain authorization object to authorization center 308.For guaranteeing the integrality and the reliability of communication information, the authorization object request of obtaining 357 can utilize the private key of set-top box to carry out digital signature; Authorization object obtains response 358 and can utilize the private key of authorization center to carry out digital signature too.After set-top box 301 authorized objects and the installation, just can accept encrypted media streams 361 and handle, obtain decrypt media stream for broadcast with reference to the flow process among the figure 2.
Claims (10)
1. the encryption method of a Media Stream comprises the steps:
(1) Media Stream transmit leg structure foundation key, package key;
(2) Media Stream transmit leg structure dynamic key, and, generate data encryption key according to this dynamic key and described foundation key; The mode that the Media Stream transmit leg takes not timing to change or packet-by-packet change is changed described dynamic key;
(3) the Media Stream transmit leg utilizes described data encryption key that the Media Stream that sends is encrypted, and generates encrypted media streams;
(4) the Media Stream transmit leg utilizes described package key that described dynamic key is encrypted, and generates to encrypt dynamic key, and should encrypt dynamic key and insert in the described encrypted media streams.
2. the method for claim 1 is characterized in that, in the described step (1), described package key and foundation key are identical or different.
3. the method for claim 1 is characterized in that, in the described step (4), described encryption dynamic key inserts encrypted media streams when dynamic key changes.
4. the method for claim 1 is characterized in that, in the described step (4), the Media Stream transmit leg will be encrypted dynamic key and be inserted in the packet header or inclusion of encrypted media streams; Or in described encrypted media streams, insert new bag and deposit and encrypt dynamic key.
5. method as claimed in claim 4 is characterized in that, described encryption dynamic key inserts at the critical packet place of encrypted media streams, or all inserts at each packet.
6. method as claimed in claim 5 is characterized in that, described critical packet comprises the packet of random access, the initial data packets of key frame.
7. the method for claim 1 is characterized in that, in the described step (4), the available point of encrypting dynamic key that inserts Media Stream is for to begin effectively from current data packet, or begins effectively from certain follow-up packet.
8. the decryption method of a Media Stream comprises the steps:
(1) the Media Stream recipient receives foundation key and package key from the Media Stream transmit leg;
(2) the Media Stream recipient separates from the encrypted media streams that receives and encrypts dynamic key, and utilizes the package key receive that this has been encrypted dynamic key to be decrypted, to obtain dynamic key; The mode that the Media Stream transmit leg takes not timing to change or packet-by-packet change is changed described dynamic key;
(3) the Media Stream recipient utilizes the foundation key that receives and deciphers the dynamic key that obtains, and generates data encryption key;
(4) the Media Stream recipient utilizes the data encryption key of generation that the encrypted media streams that receives is decrypted.
9. method as claimed in claim 8 is characterized in that, in the described step (1), the Media Stream transmit leg passes through the method for safety jointly with described foundation key and package key, or respectively by the method for safety, sends to the Media Stream recipient.
10. method as claimed in claim 9 is characterized in that, described method by safety sends, and is the PKI that utilizes the Media Stream recipient, and foundation key and/or package key are handled and sent; And/or utilize the private key of Streaming Media transmit leg, the message that comprises foundation key and/or package key is carried out digital signature handle and send.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2006101503287A CN1946018B (en) | 2006-10-26 | 2006-10-26 | Encrypting and de-encrypting method for medium flow |
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| CN2006101503287A CN1946018B (en) | 2006-10-26 | 2006-10-26 | Encrypting and de-encrypting method for medium flow |
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| CN1946018A CN1946018A (en) | 2007-04-11 |
| CN1946018B true CN1946018B (en) | 2011-01-19 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101227271B (en) * | 2008-01-25 | 2012-03-07 | 中兴通讯股份有限公司 | Method and apparatus for enciphering and deciphering of contents |
| CN101247520B (en) * | 2008-02-27 | 2011-05-18 | 北京航空航天大学 | Video data enciphering/deciphering method |
| CN101247472B (en) * | 2008-03-26 | 2010-07-21 | 北京航空航天大学 | De-interlacing processing method based on movement compensation |
| CN102026180A (en) * | 2009-09-15 | 2011-04-20 | 中国移动通信集团公司 | M2M transmission control method, device and system |
| CN104284329A (en) * | 2014-09-27 | 2015-01-14 | 无锡市恒通智能交通设施有限公司 | Client-side data encryption transmission method |
| KR101944741B1 (en) * | 2016-10-28 | 2019-02-01 | 삼성에스디에스 주식회사 | Apparatus and method for encryption |
| CN109995712B (en) * | 2017-12-29 | 2021-10-01 | 中国移动通信集团湖北有限公司 | Data encryption and decryption method, device, equipment and medium |
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| WO2006038204A1 (en) * | 2004-10-08 | 2006-04-13 | Koninklijke Philips Electronics N.V. | User based content key encryption for a drm system |
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