Method and apparatus for simultaneously encrypting and compressing data

• US 6,154,542 A
• Filed: 12/17/1997
• Issued: 11/28/2000
• Est. Priority Date: 12/17/1997
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Crandall, Richard E.
• Primary Examiner(s): Laufer, Pinchus M.
• Assistant Examiner(s): LATHAM, BRYAN S
• Application Number:
  US08/992,683
• Time in Patent Office: 1,077 Days
• Field of Search: 380/28, 380/45, 380/269, 705/51
• US Class Current: 380/28
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04L 2209/30 Compression, e.g. Merkle-Damgard construction
• CPC Class Codes: H04L 9/08 Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords network architectures or network communication protocols for supporting key management in a packet data network H04L63/06

Abstract

A method and apparatus for simultaneously encrypting and compressing data identifies an encryption key and uses the encryption key to identify one compression algorithm from a set of compression algorithms. The data is then compressed according to the one compression algorithm.

Claims

1. A method for simultaneously encrypting and compressing input data, the method comprising:

identifying an encryption key;

using the encryption key to determine a value for a variable in a compression algorithm, the value identifying one compression algorithm from a set of compression algorithms defined by a set of values for the variable; and

compressing first data of the input data according to the one compression algorithm,

wherein compressing the first data with the one compression algorithm as identified by the encryption key simultaneously encrypts the first data without the use of a separate encryption algorithm.

2. The method of claim 1, wherein the first data comprises a single character.

3. The method of claim 1, wherein the first data comprises all of the input data.

4. The method of claim 1, wherein using the encryption key comprises using a single bit of the encryption key to identify the one compression algorithm from the set of compression algorithms.

5. The method of claim 4, further comprising:

using the encryption key to determine a second value for the variable to identify a second compression algorithm from the set of compression algorithms; and

compressing second data of the input data according to the second compression algorithm.

6. The method of claim 1, wherein the set of compression algorithms comprise a plurality of move-forward compression algorithms.

7. The method of claim 6, wherein an amount the first data is to be moved forward according to the plurality of move-forward compression algorithms is dependent on a single bit, corresponding to the first data, of the encryption key.

8. The method of claim 1, further comprising permuting the first data prior to compressing the first data.

9. An apparatus for simultaneously encrypting and compressing input data, the apparatus comprising:

a compressor set which includes a plurality of compression algorithms defined by a set of values for a variable in a compression algorithm; and

a comcryptor to identify one compression algorithm of the plurality of compression algorithms based at least in part on using an encryption key to determine the value of the variable and to compress first data of the input data according to the one compression algorithm, wherein compressing the first data with the one compression algorithm as identified by the encryption key simultaneously encrypts the first data without the use of a separate encryption algorithm.

10. The apparatus of claim 9, wherein the first data comprises a single character.

11. The apparatus of claim 9, wherein the first data comprises all of the input data.

12. The apparatus of claim 9, wherein the comcryptor is further operative to use a single bit of the encryption key to identify the one compression algorithm of the plurality of compression algorithms.

13. The apparatus of claim 12, wherein the comcryptor is further operative to use the encryption key to determine a second value of the variable to identify a second compression algorithm of the plurality of compression algorithms, and to compress second data of the input data according to the second compression algorithm.

14. The apparatus of claim 9, wherein the plurality of compression algorithms comprise a plurality of move-forward compression algorithms.

15. The apparatus of claim 14, wherein an amount the first data is to be moved forward according to the plurality of move-forward compression algorithms is dependent on a single bit, corresponding to the first data, of the encryption key.

16. The apparatus of claim 9, wherein the comcryptor is further operative to permute the first data prior to compressing the first data.

17. A machine-readable medium having stored thereon a plurality of instructions, designed to be executed by a processor, for implementing a function to:

identify an encryption key;

use the encryption key to determine a value for a variable in a compression algorithm, the value identifying one compression algorithm from a set of compression algorithms defined by a set of values for the variable; and

compress first data according to the one compression algorithm, wherein compressing the first data with the one compression algorithm as identified by the encryption key simultaneously encrypts the first data without the use of a separate encryption algorithm.

18. The machine-readable medium of claim 17, wherein the first data comprises a single character.

19. The machine-readable medium of claim 17, wherein the function to use the encryption key comprises using a single bit of the encryption key to identify the one compression algorithm from the set of compression algorithms.

20. The machine-readable medium of claim 19, wherein the function is further operative to:

use the encryption key to determine a second value for the variable to identify a second compression algorithm from the set of compression algorithms; and

compress second data according to the second compression algorithm.

21. The machine-readable medium of claim 17, wherein the set of compression algorithms comprise a plurality of move-forward compression algorithms.

22. The machine-readable medium of claim 21, wherein an amount the first data is to be moved forward according to the plurality of move-forward compression algorithms is dependent on a single bit, corresponding to the first data, of the encryption key.

23. The machine-readable medium of claim 17, wherein the function is further operative to permute the first data prior to compressing the first data.