Dynamic system bus encryption using improved differential transitional encoding

• US 7,248,696 B2
• Filed: 09/12/2002
• Issued: 07/24/2007
• Est. Priority Date: 09/12/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Johns, Charles Ray, Craft, David John
• Primary Examiner(s): Revak; Christopher
• Application Number:
  US10/242,525
• Publication Number:
  US 20040052375A1
• Time in Patent Office: 1,776 Days
• Field of Search: None
• US Class Current: 380/263
• 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, comprising:

receiving, by a data bus transmitter coupled to a data bus, a first input data packet;

mapping the first input data packet to a corresponding one of a plurality of different encrypted logic status values dependent upon a selected pseudo-random number in accordance with a selected mapping function and a selected bus cycle, to generate a first encrypted data packet;

wherein the selected mapping function employs differential transitional encoding based on the selected pseudo-random number;

wherein the selected pseudo-random number is associated with the selected bus cycle, from a plurality of pseudo-random numbers and a plurality of bus cycles; and

transmitting the first encrypted data packet to a data bus receiver coupled to the data bus.

2. The method of claim 1, wherein the selected mapping function is selected from a plurality of mapping functions comprising at least twenty-four mapping functions, each mapping function associated with a selected bus cycle.

3. The method of claim 1, further comprising:

receiving a second input data packet; and

mapping the second input data packet to a corresponding one of the plurality of different encrypted logic status values dependent upon a selected pseudo-random number in accordance with a different selected mapping function and a different selected bus cycle than the selected mapping function and selected bus cycle employed in the mapping of the first input data packet, to generate a second encrypted data packet.

4. The method of claim 1, wherein the selected bus cycle is selected as a function of the first encrypted data packet.

5. The method of claim 1, wherein the selected bus cycle comprises a plurality of synchronous bus transfer cycles.

6. The method of claim 5, wherein at least two of the plurality of synchronous bus transfer cycles employ differing selected mapping functions.

7. The method of claim 1, further comprising:

receiving, by the data bus receiver, the first encrypted data packet;

determining the selected bus cycle;

determining the selected pseudo-random number based on the selected bus cycle;

determining the selected mapping function based on the selected pseudo-random number;

and

decoding the first encrypted data packet based on the selected mapping function.

8. The method of claim 7, wherein the step of determining the selected bus cycle comprises receiving indicia of the selected bus cycle.

9. A system, comprising:

a data bus;

a data bus transmitter coupled to the data bus and configured to receive a first input data packet;

the data bus transmitter further configured to select a selected bus cycle from a plurality of bus cycles and to select a selected pseudo-random number from a plurality of pseudo-random numbers;

wherein the data bus transmitter is further configured to map the first input data packet to a corresponding one of a plurality of different encrypted logic status values in accordance with a selected mapping function, to generate a first encrypted data packet;

wherein the selected mapping function is selected from a plurality of mapping functions based on the selected bus cycle and the selected pseudo-random number;

the data bus transmitter further configured to encode the first encrypted data packet in a differential transitional encoding, to generate a first encoded data packet; and

the data bus transmitter further configured to transmit the first encoded data packet to a data bus receiver coupled to the data bus.

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

11. The system of claim 9, wherein the data bus transmitter is further configured to change the selected bus cycle at each one of a plurality of clock cycles.

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

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

14. The system of claim 9, wherein the data bus transmitter and the data bus receiver are configured to establish a plurality of temporally synchronous selected bus transfer cycles.

15. The system of claim 14, wherein at least two selected bus cycles of the plurality of temporally synchronous selected bus cycles each employ a different mapping function.

16. The system of claim 9, wherein the data bus receiver is configured to:

receive the first encoded data packet;

determine the selected bus cycle;

determine the selected pseudo-random number based on the selected bus cycle;

determine the selected mapping function based on the selected pseudo-random number; and

decode the first encoded data packet based on the selected mapping function.

17. A computer program product for dynamically encrypting a data bus, the computer program product having a medium with a computer program embodied thereon, the computer program comprising:

computer code for receiving, by a data bus transmitter coupled to a data bus, a first input data packet;

computer code for mapping the first input data packet to a corresponding one of a plurality of different encrypted logic status values dependent upon a selected pseudo-random number in accordance with a selected mapping function and a selected bus cycle, to generate a first encrypted data packet;

wherein the selected mapping function employs differential transitional encoding based on the selected pseudo-random number;

wherein the selected pseudo-random number is associated with the selected bus cycle, from a plurality of pseudo-random numbers and a plurality of bus cycles; and

computer code for transmitting the first encrypted data packet to a data bus receiver coupled to the data bus.

18. The computer program product of claim 17, further comprising:

computer code for receiving, by the data bus receiver, the first encrypted data packet;

computer code for determining the selected bus cycle;

computer code for determining the selected pseudo-random number based on the selected bus cycle;

computer code for determining the selected mapping function based on the selected pseudo-random number; and

computer code for decoding the first encrypted data packet based on the selected mapping function.

19. A processor for dynamically encrypting a data bus, the processor including a computer program comprising:

computer code for receiving, by a data bus transmitter coupled to a data bus, a first input data packet;

computer code for mapping the first input data packet to a corresponding one of a plurality of different encrypted logic status values dependent upon a selected pseudo-random number in accordance with a selected mapping function and a selected bus cycle, to generate a first encrypted data packet;

wherein the selected mapping function employs differential transitional encoding based on the selected pseudo-random number;

wherein the selected pseudo-random number is associated with the selected bus cycle, from a plurality of pseudo-random numbers and a plurality of bus cycles; and

computer code for transmitting the first encrypted data packet to a data bus receiver coupled to the data bus.

20. The processor of claim 19, further comprising:

computer code for receiving, by the data bus receiver, the first encrypted data packet;

computer code for determining the selected bus cycle;

computer code for determining the selected pseudo-random number based on the selected bus cycle;

computer code for determining the selected mapping function based on the selected pseudo-random number; and

computer code for decoding the first encrypted data packet based on the selected mapping function.