Method and system for encryption/decryption of scalable video bitstream for conditional access control based on multidimensional scalability in scalable video coding

• US 20070116277A1
• Filed: 11/17/2006
• Published: 05/24/2007
• Est. Priority Date: 11/17/2005
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Original Assignee: Research and Industrial Cooperation Group, Samsung Electronics Co. Ltd.
• Inventors: Ro, Yong-Man, Bae, Tae-Meon, Won, Yong-Geun
• Granted Patent: US 8,514,926 B2
• Time in Patent Office: Days
• US Class Current: 380/201
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 21/234327 by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/23476 by partially encrypting, e.g. encrypting the ending portion of a movie
• CPC Class Codes: H04N 21/44055 by partially decrypting, e.g. decrypting a video stream that has been partially encrypted
• CPC Class Codes: H04N 7/167 Systems rendering the television signal unintelligible and subsequently intelligible

Abstract

Disclosed is a system and method for encryption of a scalable video coding (SVC) bitstream, which is the next-generation coding technology. The encryption method encrypts Nation Adaptation Layer (NAL) data identified according to multidimensional scalability for space, time, and quality with respect to a bitstream created after an SVC encoding, thereby providing a multidimensional scalability function for space, time, and quality even after the encryption, so that the scalability is also maintained even in a bitstream extraction process after the encryption. According to such a scalable encryption method, a specific portion of an encrypted bitstream is removed in a bitstream extraction process, and user access to the bitstream is limited based on a combination of keys for accessing a specific scalability. Therefore, it is possible to protect scalable video content and to access the video content based on scalabilities.

Claims

1. A scalable video bitstream encryption/decryption system, comprising:

a scalable video coding (SVC) bitstream encryption section for encrypting a scalable video bitstream;

a bitstream extraction unit for extracting network abstraction layer (NAL) data of a specific scalability from the SVC bitstream; and

an SVC bitstream decryption section for decrypting the scalable video bitstream transmitted from the SVC bitstream encryption section, the SVC bitstrearn encryption section comprising;

an SVC bitstream creation unit for creating NAL data and headers of the NAL data according to preset scalabilities by using an input video signal, and creating an SVC bitstream including the NAL data and the NAL headers;

a NAL data identification unit for identifying NAL data to be encrypted from the NAL data included in the SVC bitstream, and extracting scalability information from the NAL data to be encrypted;

a key input unit for outputting an encryption key corresponding to the scalability information; and

a data encryption unit for encrypting NAL data having scalability information equal to the extracted scalability information based on an SVC syntax by using the encryption key.

2. The system as claimed in claim 1, wherein the NAL data identification unit identifies the NAL data to be encrypted by using NAL header information of a NAL unit included in the SVC bitstream.

3. The system as claimed in claim 2, wherein the NAL data identification unit extracts the scalability information from the NAL header.

4. The system as claimed in claim 1, wherein the data encryption unit comprises:

a seed creation module for creating a seed value, which corresponds to the scalability information and is used to encrypt NAL data corresponding to a scalability specified by the scalability information;

an encryption module for encrypting the NAL data to be encrypted by using the created seed value; and

a seed encryption module for encrypting the created seed value by using the encryption key and inserting the encrypted seed value into the encrypted NAL data.

5. The system as claimed in claim 4, wherein the encryption module comprises:

a random value generator for receiving the created seed value from the seed creation module and generating a pseudo-random value according to the seed value; and

a NAL-data-based encryptor for extracting a specific value from the NAL data to be encrypted and changing the extracted value based on the pseudo-random value generated according to the seed value.

6. The system as claimed in claim 5, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the NAL data to be encrypted.

7. The system as claimed in claim 1, wherein a number of pieces of scalability information is at least two.

8. The system as claimed in claim 7, wherein the key input unit computes a number of encryption keys corresponding to each piece of the scalability information and provides the encryption keys when the number of pieces of the scalability information is at least two, and the data encryption unit encrypts NAL data having equal scalability information based on a NAL unit based on an SVC syntax by using the encryption key.

9. The system as claimed in claim 8, wherein the data encryption unit comprises:

a seed creation module for creating seed values corresponding to each piece of the scalability information;

an encryption module for encrypting NAL data according to each piece of the scalability information by using the created seed values; and

a seed encryption module for encrypting the created seed values by using each encryption key and inserting the encrypted seed values into the encrypted NAL data.

10. The system as claimed in claim 9, wherein the encryption module comprises:

a random value generator for receiving the created seed values from the seed creation module and generating pseudo-random values according to the seed values; and

a NAL-data-based encryptor for extracting specific values from NAL data to be encrypted, which correspond to each piece of the scalability information, and changing the specific values by using the pseudo-random values.

11. The system as claimed in claim 10, wherein the NAL-data-based encryptor encrypts NAL data based on a NAL unit so that the NAL data can be applied to a bitstream extraction process while maintaining scalability before and after encryption.

12. The system as claimed in claim 10, wherein the NAL-data-based encryptor encrypts NAL data such that a NAL unit having Fine Grain Scalability (FGS) data can be decrypted even when the NAL unit is separated in a bitstream extraction process.

13. The system as claimed in claim 10, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the NAL data to be encrypted.

14. The system as claimed in claim 8, wherein a number of the encryption keys is obtained by

15. A scalable video bitstream encryption/decryption system, comprising:

a scalable video coding (SVC) bitstream encryption section for encrypting a scalable video bitstream;

a bitstream extraction unit for extracting network abstraction layer (NAL) data of a specific scalability from the SVC bitstream; and

an SVC bitstream decryption section for decrypting the scalable video bitstream transmitted from the SVC bitstream encryption section, the SVC bitstream decryption section comprising;

an SVC bitstream reception unit for receiving an SVC bitstream which includes a plurality of NAL data corresponding to scalabilities extracted by the bitstream extraction unit;

a key input unit for providing a decryption key;

a data decryption unit for decrypting the NAL data by using the decryption key; and

an SVC bitstream decoding unit for decoding an SVC bitstream including the decrypted NAL data.

16. The system as claimed in claim 15, wherein the data decryption unit decrypts NAL data having different scalabilities in an order identical to a decoding order based on relation among the scalabilities.

17. The system as claimed in claim 15, wherein the data decryption unit enables decoding of the SVC bitstream, although an encrypted SVC bitstream is incompletely decrypted because all required decryption keys do not exist.

18. The system as claimed in claim 15, wherein the data decryption unit comprises:

a seed extraction module for determining if the extracted NAL data has been encrypted and extracting an encrypted seed value for decrypting the NAL data when the NAL data has been encrypted;

a key input module for outputting a decryption key for decrypting the encrypted seed value;

a seed decryption module for decrypting the encrypted seed value by using the decryption key input from the key input module; and

a decryption module for receiving the decrypted seed value and decrypting the NAL data by using the decrypted seed value.

19. The system as claimed in claim 15, wherein the decryption module comprises:

a random value generator for receiving the seed value and generating a pseudo-random value according to the seed value; and

a NAL data decryptor for extracting a specific value from the encrypted NAL data and restoring the extracted value based on the pseudo-random value.

20. The system as claimed in claim 19, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the NAL data to be encrypted.

21. The system as claimed in claim 15, wherein the SVC bitstream reception unit receives at least two encrypted NAL data which have different scalabilities.

22. The system as claimed in claim 21, wherein the key input module provides decryption keys so as to decrypt each of the encrypted NAL data, and the data decryption unit decrypts each of the NAL data by using the decryption keys.

23. The system as claimed in claim 22, wherein the data decryption unit comprises:

a seed decryption module for decrypting encrypted seed values by using the decryption keys; and

a decryption module for decrypting each of the NAL data based on the at least two extracted encrypted scalabilities by using the decrypted seed values.

24. The system as claimed in claim 23, wherein the data decryption unit comprises:

a random value generator for receiving the decrypted seed values from the seed decryption module and generating pseudo-random values according to the seed values; and

a NAL data decryptor for extracting specific values from the at least two encrypted NAL data and restoring the specific values by using the pseudo-random values.

25. The system as claimed in claim 24, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the NAL data to be encrypted.

26. The system as claimed in claim 22, wherein the key input module computes a number of the decryption keys based on

27. The system as claimed in claim 25, wherein the SVC bitstream decoding unit adds noise during a decoding operation when a part of NAL data has not been decrypted, so that a degree of noise is changed depending on a number of scalabilities corresponding to non-decrypted NAL data.

28. A method for encrypting a scalable video coding (SVC) bitstream by an SVC bitstream encryption section in a scalable video bitstream encryption/decryption system, the SVC bitstream encryption section for encrypting a scalable video bitstream, a bitstream extraction unit for extracting network abstraction layer (NAL) data of a specific scalability from the SVC bitstream, and a decryption section for decrypting the scalable video bitstream transmitted from the SVC bitstream encryption section, the method comprising the steps of:

encoding an input video signal into an SVC bitstream which includes NAL data and NAL headers according to scalabilities;

identifying NAL data to be encrypted in the NAL data included in the SVC bitstream;

receiving encryption keys, which correspond to the NAL data to be encrypted and used to encrypt the NAL data to be encrypted; and

encrypting the NAL data to be encrypted based on an SVC bitstream syntax.

29. The method as claimed in claim 28, wherein, in the NAL data identification step, the NAL data to be encrypted is identified by using the NAL header, and scalability information is extracted from the NAL data to be encrypted.

30. The method as claimed in claim 28, wherein the encryption step comprises:

creating seed values corresponding to the scalability information;

generating pseudo-random values according to the created seed values;

extracting specific values from the NAL data to be encrypted;

encrypting the NAL data to be encrypted by changing the extracted specific values using the pseudo-random values; and

encrypting the seed values of corresponding scalabilities by using the encryption keys.

31. The method as claimed in claim 30, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the NAL data to be encrypted.

32. A method for decrypting a scalable video coding (SVC) bitstream by an SVC bitstream decryption section in a scalable video bitstream encryption/decryption system, that includes an SVC bitstream encryption section for encrypting a scalable video bitstream, a bitstream extraction unit for extracting a network abstraction layer (NAL) unit of a required specific scalability from the SVC bitstream, and the SVC bitstream decryption section for decrypting the scalable video bitstream transmitted from the SVC bitstream encryption section, the method comprising the steps of:

receiving an SVC bitstream including a NAL unit according to scalabilities extracted by the bitstream extraction unit;

decrypting encrypted NAL data according to scalabilities when the extracted NAL data include the encrypted NAL data; and

decoding the decrypted NAL data and non-decrypted NAL data.

33. The method as claimed in claim 32, wherein, in the decryption step, NAL data having different scalabilities are decrypted in an order equal to a decoding order of the SVC bitstream in relation to the scalabilities.

34. The method as claimed in claim 32, wherein the decryption step comprises:

extracting seed values of scalabilities corresponding to the encrypted NAL data from the encrypted NAL data;

decrypting the seed values by using a pre-allocated decryption key when the seed values have been encrypted;

generating pseudo-random values according to the decrypted seed values;

extracting specific values from the encrypted NAL data according to scalabilities;

restoring the extracted specific values by using the pseudo-random values generated according to the seed values based on each corresponding scalability; and

restoring the encrypted NAL data.

35. The method as claimed in claim 34, wherein the specific value includes sign values of a texture value, a motion vector value, and a Fine Grain Scalability (FGS) data value, which are extracted from the encrypted NAL data.

36. The method as claimed in claim 35, wherein, in the decoding step, noise is added when a part of NAL data has not been decrypted, so that a degree of noise is changed depending on a number of scalabilities corresponding to non-decrypted NAL data.