Dynamic systm bus encryption using improved differential transitional encoding

• US 20040052375A1
• Filed: 09/12/2002
• Published: 03/18/2004
• Est. Priority Date: 09/12/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Johns, Charles Ray, Craft, David John
• Granted Patent: US 7,248,696 B2
• Time in Patent Office: Days
• US Class Current: 380/256
• CPC Class Codes: H04L 2209/125 Parallelization or pipelining, e.g. for accelerating processing of cryptographic operations
• CPC Class Codes: H04L 2209/34 Encoding or coding, e.g. Huffman coding or error correction
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator

Abstract

The present invention provides data encryption for a differential bus employing transitional coding. The present invention maps, encodes and encrypts input data as a logic status for a given bus transfer cycle. The mapping, encoding and encrypting of the input data changes from bus transfer cycle to bus transfer cycle. The mapping, encoding and encrypting is a function of a pseudo-random number. A logic status is differentially transmitted from a bus transmitter to a bus receiver, to be mapped, decrypted and decoded as the corresponding output data.

Claims

1. A method for dynamically encrypting a data bus employing differential transitional coding, the bus having encryption logic and decryption logic employable in association with a mapping function, comprising:

establishing a first bus cycle; and

dynamically and pseudo-randomly changing the mapping function to establish a different bus cycle later in time.

2. The method of claim 1, wherein the step of dynamically and pseudo-randomly changing the mapping function employs linear feedback shift register to dynamically and pseudo-randomly change the mapping function.

3. The method of claim 1, wherein the step of establishing a bus cycle employs decryption and encryption with the differential transmission of encoded data.

4. The method of claim 1, wherein the step of dynamically and pseudo-randomly changing the mapping function of each bus cycle comprises employing twenty-four mapping functions to encrypt and decrypt the transmitted data.

5. The method of claim 1, wherein the data mapping function selected is a function of the data output of the differential bus.

6. The method of claim 1, wherein the step of dynamically and pseudo-randomly changing the mapping function occurs each bus cycle.

7. The method of claim 1, wherein the step of establishing a bus cycle comprises a step of establishing a plurality of substantially temporally synchronous bus transfer cycles.

8. The method of claim 7, wherein at least two bus cycles of the plurality of substantially parallel bus transfer cycles employ differing mapping functions.

9. A system for dynamically decrypting a bus having differential transitional coding, comprising:

a physical representation of a pseudo-random number;

a plurality of data mapping circuits for providing decryption logic, wherein the decryption logic is selected as a function of the physical representation of a pseudo-random number;

a data bus differential transmitter for providing encrypted transitional coding as a function of the selected decryption logic; and

a data bus differential receiver for receiving encrypted transitional coding from the data bus differential transmitter in an asserted bus cycle.

10. The system of claim 9, wherein the representation of a pseudo-random number is created by a linear feedback shift register.

11. The system of claim 9, wherein the plurality of mapping functions comprise twenty-four mapping circuits.

12. The system of claim 9, wherein a bus line group, comprising four bus lines, is coupled to both the differential transmitter and the differential receiver.

13. The system of claim 9, wherein a bus line group, comprising six bus lines, is coupled to both the differential transmitter and the differential receiver.

14. The system of claim 9, wherein the differential bus transmitter and differential bus receiver are employable to establish a plurality of substantially temporally synchronous bus transfer cycles.

15. The system of claim 14, wherein at least two bus cycles of the plurality of bus cycles each employ a substantially different mapping function per bus transfer cycle.

16. The system of claim 14, wherein the data plurality of mapping circuits change the mapping function for every bus cycle.

17. A computer program product for dynamically encrypting a data bus employing transitional coding, the computer program having encryption logic and decryption logic employable with a mapping function, the computer program product having a medium with a computer program embodied thereon, the computer program comprising:

computer code for establishing a bus cycle; and

computer code for dynamically and pseudo-randomly changing the mapping function for the next bus cycle.

18. The computer code for dynamically and pseudo-randomly changing the mapping function, wherein the computer code is further employable to change the mapping function for each bus cycle.

19. A processor for dynamically encrypting a data bus employing differential transitional coding, the processor having encryption logic and decryption logic employable in association with a mapping function, the processor including a computer program comprising:

computer code for establishing a bus cycle; and

computer code for dynamically and pseudo-randomly changing the mapping function for the next bus cycle.

20. The processor of claim 19, wherein the computer code for dynamically and pseudo-randomly changing the mapping function is further employable for changing the mapping function for each bus cycle.