Cryptographic system configured to perform a mixed radix conversion with a priori defined statistical artifacts

• US 8,363,830 B2
• Filed: 02/07/2008
• Issued: 01/29/2013
• Est. Priority Date: 02/07/2008
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Michaels, Alan J., Chester, David B.
• Primary Examiner(s): Patel, Ashok
• Assistant Examiner(s): COSBY, LAWRENCE V
• Application Number:
  US12/027,658
• Publication Number:
  US 20090202067A1
• Time in Patent Office: 1,818 Days
• Field of Search: 380/42
• US Class Current: 380/42
• CPC Class Codes: G06F 7/584 using finite field arithmetic, e.g. using a linear feedback shift register
• CPC Class Codes: G06F 7/724 Finite field arithmetic for error detection or correction in general H03M13/00, in computers G06F11/10

Abstract

A cryptographic system (CS) is provided. The CS (800) comprises a data stream receiving means (DSRM), a generator (702), a mixed radix converter (MRC) and an encryptor (908). The DSRM (902) is configured to receive a data stream (DS). The generator is configured to selectively generate a random number sequence (RNS) utilizing a punctured ring structure. The MRC (704) is coupled to the generator and configured to perform a mixed radix conversion to convert the RNS from a first number base to a second number base. The encryptor is coupled to the DSRM and MRC. The encryptor is configured to generate an altered data stream by combining the RNS in the second number base with the DS. The punctured ring structure and the MRC are configured in combination to produce an RNS in the second number base which contains a priori defined statistical artifacts after the mixed radix conversion.

Claims

1. A cryptographic system, comprising:

a data stream receiving means configured for receiving an input data stream;

a generator configured for selectively generating a random number sequence utilizing a ring structure which has been punctured;

a mixed radix converter coupled to said generator and configured for performing a mixed radix conversion to convert said random number sequence from a first number base to a second number base;

an encryptor coupled to said data stream receiving means and said mixed radix converter, said encryptor configured for generating an modified data stream by combining said random number sequence in said second number base with said input data stream; and

wherein said ring structure which has been punctured and said mixed radix converter are configured in combination to produce a random number sequence in said second number base which is exclusive of any statistical artifacts associated with said mixed radix conversion.

2. The cryptographic system according to claim 1, wherein said first number base and said second number base are respectively defined by a first Galois field characteristic and a second Galois field characteristic.

3. The cryptographic system according to claim 2, wherein said first Galois field characteristic is mutually prime with respect to said second Galois field characteristic.

4. The cryptographic system according to claim 2, wherein said second Galois field characteristic is selected as a finite field size which is smaller as compared to a finite field size of a first Galois field.

5. The cryptographic system according to claim 4, wherein said ring structure which has been punctured comprised n element(s) which have been removed therefrom to eliminate at least one statistical artifact in said random number sequence expressed in said second number base, wherein n is determined based on a mathematical relation between a number of elements in said first Galois field and a number of elements in a second Galois field.

6. The cryptographic system according to claim 5, wherein n is determined based on a remainder value resulting from a quotient of said number of elements in said first Galois field divided by said number of elements in said second Galois field.

7. The cryptographic system according to claim 6, wherein said mixed radix conversion produces a plurality of equivalence classes in said second number base, and said n elements which have been removed from said ring structure are selected to ensure that each equivalence class has an equal or desired number of elements after said mixed radix conversion.

8. The cryptographic system according to claim 1, wherein said encryptor includes at least one of a multiplier, an adder, a digital logic device and a feedback mechanism.

9. The cryptographic system according to claim 1, where in said encryptor is configured for performing at least one of a standard multiplication operation, a multiplication in a Galois extension field operation, an addition modulo q operation, a subtraction modulo q operation and a bitwise logic operation.

10. The cryptographic system according to claim 1, further comprising a truncation device coupled to said mixed radix converter and configured for selecting a truncated portion of said random number sequence in said second number base.

11. The cryptographic system according to claim 10, further comprising a size converter coupled between said truncation device and said encryptor, said size converter configured for converting said truncated portion from a size GF[M] to a size n if said input data stream is of a size GF[n] or GF[n/d], where d is an even divisor of n.

12. The cryptographic system according to claim 1, wherein said input data stream is expressed in said second number base.

13. The cryptographic system according to claim 1, wherein chosen statistical artifacts with a priori defined statistical distributions are induced into said random number sequence expressed in said second number base.

14. The cryptographic system according to claim 1, further comprising a second ring structure and a second mixed radix converter configured in combination to produce a decryption sequence.

15. The cryptographic system according to claim 14, further comprising a modified data stream receiving means, a decryptor electronically connected to said modified data stream receiving means, and said second mixed radix converter, wherein said decryptor is configured for generating decrypted data by performing a decryption method utilizing said modified data stream and said decryption sequence.

16. A cryptographic system, comprising:

a data stream receiving means configured for receiving an input data stream;

a generator configured for selectively generating a random number sequence utilizing a ring structure which has been punctured;

a mixed radix converter coupled to said generator and configured for performing a mixed radix conversion to convert said random number sequence from a first number base to a second number base;

a truncation device coupled to said mixed radix converter and configured for selecting a truncated portion of said random number sequence in said second number base

an encryptor coupled to said data stream receiving means and said truncation device, said encryptor configured for generating a modified data stream by combining said random number sequence in said second number base with said input data stream; and

wherein said ring structure which has been punctured and said mixed radix converter are configured in combination to produce a random number sequence in said second number base which is exclusive of any undesired statistical artifacts associated with said mixed radix conversion.

17. The cryptographic system according to claim 16, further comprising a second ring structure and a second mixed radix converter configured in combination to produce a decryption sequence.

18. The cryptographic system according to claim 17, further comprising a modified data stream receiving means, a decryptor electronically connected to said modified data stream receiving means, and said second mixed radix converter, wherein said decryptor is configured for generating decrypted data by performing a decryption method utilizing said modified data stream and said decryption sequence.

19. The cryptographic system according to claim 16, further comprising a size converter coupled between said truncation device and said encyrptor, said size converter configured for converting said truncated portion from a size GF[M] to a size n if said input data stream is of a size GF[n] or GF[n/d], where d is an even divisor of n.