Method and system for encoding multimedia content based on secure coding schemes using stream cipher

• US 20100067688A1
• Filed: 09/18/2009
• Published: 03/18/2010
• Est. Priority Date: 09/18/2008
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Au, Oscar Chi Lim, Zhou, Jiantao
• Granted Patent: US 8,189,776 B2
• Time in Patent Office: Days
• US Class Current: 380/43
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/26613 for generating or managing keys in general key distribution for secret or secure communication involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] H04L9/083; network support of key management H04L63/06; key management for network security in communication control or processing H04W12/04
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

Described herein are various embodiments of a coding technique that utilize a stream cipher for switching between first and second coding conventions for encoding a symbol sequence. The first coding convention specifies a first mapping between a symbol and a first codeword and the second coding convention specified a second mapping between the symbol and a second codeword. According to the invention, a key generated by the stream cipher is used to selected one of the first and second coding convention and the mapping of the selected coding convention is then utilized for encoding the symbol.

Claims

1. A method for encrypting data comprising:

obtaining a symbol and a cipher key from a key stream generated by a stream cipher;

selecting one of first and second universal coding conventions in accordance with the cipher key; and

encoding the symbol to a codeword in accordance with the selected universal coding convention.

2. The method of claim 1, wherein the cipher key has a binary value.

3. The method of claim 2, wherein the stream cipher is selected from a group of A5/1, A5/2, FISH, Grain, HC-256, ISAAC, MUGI, PANAMA, Phelix, Pike, Py, Rabbit, RC4, Salsa20, Scream, SEAL, SNOW, SOBER-128, SOSEMANUK, Trivium, Turing, VEST, and WAKE.

4. The method of claim 1, wherein the first universal coding convention specifies a first mapping between the symbol and a first codeword and the second universal coding convention specifies a second mapping between the symbol and a second codeword.

5. The method of claim 4, the method further comprising encoding the symbol to the codeword in according to the mapping specified by the selected universal coding convention, wherein the codeword is one of the first and second codewords.

6. The method of claim 4, wherein the first mapping is specified by a first coding table associated with the first universal coding convention and the second mapping is specified by a second coding table associated with the second universal coding convention,

the method further comprising encoding the symbol by searching for the codeword in the coding table associated with the selected universal coding convention.

7. The method of claim 4, wherein the first and second universal coding conventions comply with a coding scheme selected from a group of Elias gamma coding, Elias delta coding, Elias omega coding, Exp-Golomb coding, Fibonacci coding, and Levenstein coding.

8. The method of claim 4, wherein the first and second universal coding conventions comply with different coding schemes selected from a group of Elias gamma coding, Elias delta coding, Elias omega coding, Exp-Golomb coding, Fibonacci coding, and Levenstein coding.

9. The method of claim 1, wherein the cipher key has a value selected from zero (0) and one (1), the method further comprising:

selecting the first universal coding convention for encoding the symbol when the value of the cipher key is zero (0); and

selecting the second universal coding convention for encoding the symbol when the value of the cipher key is one (1).

10. A method for encoding a sequence of symbols comprising:

generating a key stream using a stream cipher, the key stream corresponding to the sequence of symbols; and

switching between first and second coding tables in accordance with the key stream for encoding the sequence of symbols, wherein the first coding table specifies a first mapping between each one of the sequence of symbols and a first set of codewords and the second coding table specifies a second mapping between each one of the sequence of symbols and a second set of codewords.

11. The method of claim 10, switching between the first and second coding tables in accordance with the key stream for encoding the sequence of symbols further comprising performing the following steps until the sequence of symbols is exhausted:

(a) retrieving a symbol from the sequence of symbols and a key from the key stream;

(b) selecting one of the first and second coding tables based on the key;

(c) searching for a codeword that is mapped to the symbol in the selected coding table; and

(d) outputting the codeword into a bit stream;

12. The method of claim 10, wherein the key stream has binary values selected from zero (0) and one (1).

13. The method of claim 12, selecting one of the first and second coding tables based on the key further comprising:

determining the value of the key to be zero (0); and

selecting the first coding table.

14. The method of claim 12, selecting one of the first and second coding tables based on the key further comprising:

determining the value of the key to be one (1); and

selecting the second coding table.

15. The method of claim 10, wherein

the stream cipher is selected from a group including A5/1, A5/2, FISH, Grain, HC-256, ISAAC, MUGI, PANAMA, Phelix, Pike, Py, Rabbit, RC4, Salsa20, Scream, SEAL, SNOW, SOBER-128, SOSEMANUK, Trivium, Turing, VEST, and WAKE, and

the first and second coding tables comply with at least one coding scheme selected from a group of Elias gamma coding, Elias delta coding, Elias omega coding, Exp-Golomb coding, Fibonacci coding, and Levenstein coding.

16. A computer readable medium having program codes executed by one or more digital processors for encoding a symbol, the program codes comprising:

instructions for generating a key stream using a stream cipher, the key stream having a key corresponding to the symbol;

instructions for selecting one of first and second universal coding conventions in accordance with the key, wherein the first universal coding convention specifies a first mapping between the symbol and a first codeword and the second universal coding convention specifies a second mapping between the symbol and a second codeword; and

instructions for encoding the symbol in accordance with the selected universal coding convention.

17. The computer readable medium of claim 16, wherein the key has a value selected from zero (0) and one (1), the program codes further comprising:

instructions for determining the value of the key to be zero (0);

instructions for selecting the first universal coding convention in response to the value of the key;

instructions for obtaining the first codeword associated with the symbol in accordance with the first mapping of the first universal coding convention; and

instructions for outputting the first codeword.

18. The computer readable medium of claim 16, wherein the key has a value selected from zero (0) and one (1), the program codes further comprising:

instructions for determining the value of the key to be one (1);

instructions for selecting the second coding table in response to the value of the key;

instructions for obtaining the second codeword associated with the symbol in accordance with the second mapping of the second universal coding convention; and

instructions for outputting the second codeword.

19. The computer readable medium of claim 17, wherein the stream cipher is selected from a group including A5/1, A5/2, FISH, Grain, HC-256, ISAAC, MUGI, PANAMA, Phelix, Pike, Py, Rabbit, RC4, Salsa20, Scream, SEAL, SNOW, SOBER-128, SOSEMANUK, Trivium, Turing, VEST, and WAKE.

20. The computer readable medium of claim 17, wherein the first and second universal coding conventions comply with at least one coding scheme selected from a group of Elias gamma coding, Elias delta coding, Elias omega coding, Exp-Golomb coding, Fibonacci coding, and Levenstein coding.