JPEG2000 SYNTAX-COMPLIANT ENCRYPTION WITH FULL SCALABILITY

• US 20060265601A1
• Filed: 05/19/2006
• Published: 11/23/2006
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: Zhigu Holdings Limited
• Original Assignee: Microsoft Corporation
• Inventors: Zhu, Bin, Li, Shipeng, Yang, Yang
• Granted Patent: US 8,081,755 B2
• Time in Patent Office: Days
• US Class Current: 713/184
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04L 9/0637 Modes of operation, e.g. cipher block chaining [CBC], electronic codebook [ECB] or Galois/counter mode [GCM]

Abstract

A method and system is provided for encrypting an image compressed with a JPEG2000-based compression with minimal overhead so that the encrypted codestream is compliant with the syntax of the JPEG2000-based compression and can be scaled without decrypting. The encryption system generates, for each independent encryption segment of a codestream for an image, a unique initialization vector from a global initialization vector in such a way that the initialization vectors can be generated during decryption from the global initialization vector, even after truncation. The encryption system encrypts each independent encryption segment using its unique initialization vector. The encryption system ensures that the encrypted codestream is compliant with the syntax of the JPEG2000-based compression both as originally generated and as truncated by an encryption-unaware device.

Claims

1. A method for encrypting a media data, the method comprising:

identifying independent encryption segments of the media data; and

for each identified independent encryption segment,

generating an initialization vector for the independent encryption segment; and

encrypting the data of the independent encryption segment using the generated initialization vector.

2. The method of claim 1 wherein an independent encryption segment is a codeword segment from a code-block of a JPEG2000-based compression.

3. The method of claim 1 wherein an independent encryption segment is an intersection of a codeword segment and code-block contribution to a packet of a JPEG2000-based compression.

4. The method of claim 1 wherein the encrypting of an independent encryption segment applies an encryption scheme that generates syntax-compliant ciphertexts.

5. The method of claim 4 wherein the encryption scheme is a locally iterative encryption scheme.

6. The method of claim 5 wherein the locally iterative encryption scheme in cipher block chaining mode is applied to full encryption blocks and the locally iterative encryption scheme in cipher feedback mode is applied to the last partial encryption block.

7. The method of claim 4 wherein the encryption scheme is a ciphertext switching scheme.

8. The method of claim 1 wherein the media data represents an image or a video and the initialization vector for an independent encryption segment is generated from an initialization vector of the image or a frame of the video and a unique identifier of the independent encryption segment.

9. The method of claim 8 wherein an independent encryption segment is either a codeword segment of a code-block or an intersection of a codeword segment and code-block contribution to a packet of JPEG2000-based compression, and the unique identifier of an independent encryption segment is a unique identifier of the code-block and an index to a first coding pass of the independent encryption segment.

10. The method of claim 9 wherein the unique identifier of the code-block includes an indication of tile, component, resolution level, precinct, subband, and coordinate of the upper left point of the code-block.

11. A system for encrypting media data so that it is compliant with a JPEG2000-based compression, comprising:

a component that identifies code-blocks of the media data;

a component that identifies codeword segments of the code-blocks;

a component that identifies independent encryption segments from the codeword segments;

a component that independently encrypts data of each independent encryption segment; and

a component that partitions code-blocks into code-block contributions to a packet so that when a bitstream is terminated at a code-block contribution to a packet, the remaining code-block contributions to a packet can be decrypted.

12. The system of claim 11 wherein an independent encryption segment is a codeword segment from a code-block of a JPEG2000-based compression.

13. The system of claim 11 wherein an independent encryption segment is an intersection of a codeword segment and code-block contribution to a packet of JPEG2000-based compression.

14. The system of claim 11 wherein the component that encrypts generates syntax-compliant ciphertexts.

15. The system of claim 14 wherein the component that encrypts applies a locally iterative encryption scheme.

16. The system of claim 14 wherein the component that encrypts applies a ciphertext switching scheme.

17. The system of claim 11 wherein the component for encrypting

generates an initialization vector from an image or a frame initialization vector and a unique identifier of an independent encryption segment;

and

encrypts the independent encryption segment using the generated initialization vector.

18. The system of claim 17 wherein an independent encryption segment is either a codeword segment of a code-block or an intersection of a codeword segment and code-block contribution to a packet of JPEG2000-based compression, and the unique identifier of an independent encryption segment is a unique identifier of the code-block and an index to a first coding pass of the encryption segment.

19. A computer-readable medium containing a syntax-compliant encryption of data that is compressed using a JPEG2000-based compression, the syntax-compliant encryption being generated by a method comprising:

identifying code-blocks of the data;

identifying codeword segments of the code-blocks;

identifying independent encryption segments from the code-blocks; and

for each identified independent encryption segment,

generating an initialization vector for the independent encryption segment; and

encrypting the data in the encryption segment using the generated initialization vector to generate ciphertext that is compliant with the syntax of a JPEG2000-based compression.

20. The computer-readable medium of claim 19 wherein an encryption segment is either a codeword segment of a code-block or an intersection of a codeword segment and code-block contribution to a packet of a JPEG2000-based compression, and the initialization vector for an independent encryption segment is generated from an image or frame initialization vector and a unique identifier of the code-block from which the codeword segment is generated and an index to a first coding pass of the encryption segment.