Block cipher method

• US 20020118827A1
• Filed: 10/23/2001
• Published: 08/29/2002
• Est. Priority Date: 09/17/1997
• Status: Active Grant

• Current Assignee: Frank C. Luyster
• Original Assignee: Frank C. Luyster
• Inventors: Luyster, Frank C.
• Granted Patent: US 6,751,319 B2
• Time in Patent Office: Days
• US Class Current: 380/37
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 2209/125 Parallelization or pipelining, e.g. for accelerating processing of cryptographic operations
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 9/002 Countermeasures against attacks on cryptographic mechanisms network architectures or network communication protocols for protection against malicious traffic H04L63/1441
• CPC Class Codes: H04L 9/0625 with splitting of the data block into left and right halves, e.g. Feistel based algorithms, DES, FEAL, IDEA or KASUMI

Abstract

A data encryption system for encrypting an n-bit block of input in a plurality of rounds is presented, where n is preferably 128 bits or more. The data encryption system includes a computing unit for the execution of each round; memory for storing and loading segments; a bit-moving function capable of rotating, shifting, or bit-permute round segments by predetermined numbers of bits preferably to achieve active and effective fixed rotation; a linear combination function which provides new one-to-one round segments using a round operator generally from one algebraic group to combine two different one-to-one round segments taken from one one-to-one round segment set; and a nonlinear function which affects a one-to-one round segment from a particular one-to-one round segment set based on a value which depends on a preselected number of bits in a preselected location from a different one-to-one round segment from the same one-to-one round segment set. The nonlinear function is a variable rotation function or an s-box. A subkey combining function is generally employed in each round to provide new round segments by combining a round segment typically linearly with a subkey segment.

Claims

1. A method of enciphering plaintext in a block cipher, comprising:

processing round segments in a plurality of rounds of said block cipher, said processing round segments in each of said rounds comprising,

predetermined bit-moving at least one present bit-value in a present bit-position of one of said round segments of said round to determine a bit-value in an other bit-position of one of said round segments of said round, and

variable bit-moving bits of one of said round segments of said round by a number of bits dependent on a value from data of one of said round segments of said round.

2. The method of claim 1 wherein said variable bit-moving comprises variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

3. The method of claim 2 wherein said variable circular bit-rotating said bits of one of said round segments comprises variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

4. The method of claim 2 wherein said enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

5. The method of claim 2 wherein said predetermined bit-moving affects which bits affect said value of said variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said variable circular bit-rotating.

6. The method of claim 2 wherein said predetermined bit-moving comprises predetermined bit-rotating.

7. The method of claim 1 wherein said variable bit-moving comprises variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

8. The method of any of claims 1 to 7 wherein said plurality of rounds comprising at least five said rounds.

9. The method of claim 1 wherein said enciphering further comprises:

combining two of said round segments in said round using a linear mathematical operator.

10. The method of claim 9 wherein said variable bit-moving comprises variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

11. The method of claim 10 wherein said variable circular bit-rotating said bits of one of said round segments comprises variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

12. The method of claim 10 wherein said enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

13. The method of claim 10 wherein said predetermined bit-moving affects which bits affect said value of said variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said variable circular bit-rotating.

14. The method of claim 10 wherein said predetermined bit-moving comprises predetermined bit-rotating.

15. The method of claim 9 wherein said variable bit-moving comprises variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

16. The method of any of claims 9 to 15 wherein said plurality of rounds comprising at least five said rounds.

18. The system for enciphering of claim 17 wherein said means for variable bit-moving comprises means for variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

19. The system for enciphering of claim 18 wherein said means for variable circular bit-rotating said bits of one of said round segments comprises means for variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

20. The system for enciphering of claim 18 wherein said system for enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

21. The system for enciphering of claim 18 wherein said means for predetermined bit-moving affects which bits affect said value of said means for variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said means for variable circular bit-rotating.

22. The system for enciphering of claim 18 wherein said means for predetermined bit-moving comprises means for predetermined bit-rotating.

23. The system for enciphering of claim 17 wherein said means for variable bit-moving comprises means for variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

25. The system for enciphering of claim 17 wherein said enciphering further comprises:

means for combining two of said round segments in said round using a linear mathematical operator.

26. The system for enciphering of claim 25 wherein said means for variable bit-moving comprises means for variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

27. The system for enciphering of claim 26 wherein said means for variable circular bit-rotating said bits of one of said round segments comprises means for variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

28. The system for enciphering of claim 26 wherein said system for enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

29. The system for enciphering of claim 26 wherein said means for predetermined bit-moving affects which bits affect said value of said means for variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said means for variable circular bit-rotating.

30. The system for enciphering of claim 26 wherein said means for predetermined bit-moving comprises means for predetermined bit-rotating.

31. The system for enciphering of claim 25 wherein said means for variable bit-moving comprises means for variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

32. The system for enciphering of any of claims 25 to 31 wherein said plurality of rounds comprising at least five said rounds.

17. A system for enciphering plaintext in a block cipher, comprising:

means for processing round segments in a plurality of rounds of said block cipher, said means for processing round segments in each of said rounds comprising,

means for predetermined bit-moving at least one present bit-value in a present bit-position of one of said round segments of said round to determine a bit-value in an other bit-position of one of said round segments of said round, and

means for variable bit-moving bits of one of said round segments of said round by a number of bits dependent on a value from data of one of said round segments of said round.

24. The system for enciphering of any of claims 17 to 23 wherein said plurality of rounds comprising at least five said rounds.

33. A data signal propagated over a propagation medium, said data signal including enciphered plaintext, said enciphered plaintext originating from plaintext which has been enciphered by enciphering said plaintext in a block cipher, said enciphering comprising:

processing round segments in a plurality of rounds of said block cipher, said processing round segments in each of said rounds comprising,

predetermined bit-moving at least one present bit-value in a present bit-position of one of said round segments of said round to determine a bit-value in an other bit-position of one of said round segments of said round, and

variable bit-moving bits of one of said round segments of said round by a number of bits dependent on a value from data of one of said round segments of said round.

34. The data signal propagated over said propagation medium of claim 33 wherein said enciphering further comprises said variable bit-moving comprising variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

35. The data signal propagated over said propagation medium of claim 34 wherein said enciphering further comprises said variable circular bit-rotating said bits of one of said round segments comprising variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

36. The data signal propagated over said propagation medium of claim 34 wherein said enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

37. The data signal propagated over said propagation medium of claim 34 wherein said enciphering further comprises said predetermined bit-moving affecting which bits affect said value of said variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said variable circular bit-rotating.

38. The data signal propagated over said propagation medium of claim 34 wherein said enciphering further comprises said predetermined bit-moving comprising predetermined bit-rotating.

39. The data signal propagated over said propagation medium of claim 33 wherein said enciphering further comprises said variable bit-moving comprising variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

40. The data signal propagated over said propagation medium of any of claims 33 to 39 wherein said enciphering further comprises said plurality of rounds comprising at least five said rounds.

41. The data signal propagated over said propagation medium of claim 33 wherein said enciphering further comprises:

combining two of said round segments in said round using a linear mathematical operator.

42. The data signal propagated over said propagation medium of claim 41 wherein said enciphering further comprises said variable bit-moving comprising variable circular bit-rotating said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

43. The data signal propagated over said propagation medium of claim 42 wherein said enciphering further comprises said variable circular bit-rotating said bits of one of said round segments comprising variably circular bit-rotating said bits of one of said round segments having a bit-size where a log base 2 of said bit-size equals said selected number of bits of data.

44. The data signal propagated over said propagation medium of claim 42 wherein said enciphering further comprises said output primary segments having a bit-size of 32 bits or 64 bits.

45. The data signal propagated over said propagation medium of claim 42 wherein said enciphering further comprises said predetermined bit-moving affecting which bits affect said value of said variable circular bit-rotating, and at least one of said output primary segments originating from said round segment which has been rotated by said variable circular bit-rotating.

46. The data signal propagated over said propagation medium of claim 42 wherein said enciphering further comprises said predetermined bit-moving comprises predetermined bit-rotating.

47. The data signal propagated over said propagation medium of claim 41 wherein said enciphering further comprises said variable bit-moving comprising variable bit-shifting said bits of one of said round segments of said round by a number of bits dependent on said value from a selected number of bits of data in selected locations of one of said round segments of said round.

48. The data signal propagated over said propagation medium of any of claims 41 to 47 wherein said enciphering further comprises said plurality of rounds comprising at least five said rounds.