Method and apparatus for seamless crypto rekey system

• US 5,940,508 A
• Filed: 04/07/1997
• Issued: 08/17/1999
• Est. Priority Date: 04/07/1997
• Status: Expired due to Term

• Current Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Long, Craig Allen, Worger, William Robert, Schaefer, Bradley Robert
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US08/834,963
• Time in Patent Office: 862 Days
• Field of Search: 380/9, 380/21, 380/42, 380/43, 380/49, 380/50, 380/59, 380/23, 380/25, 380/45, 380/47, 380/44, 380/46, 380/48
• US Class Current: 380/273
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying

Abstract

Equipment (10, 20) for facilitating point-to-point cryptographic data communication systems is disclosed. The seamless rekey cryptosystem permits changing of the crypto key (70, 80) with no down time. The cryptosystem will facilitate seamless key installation to eliminate data loss or reduce storage required while updating the crypto key. The seamless key will allow changing the key more often, which will also provide a more robust, secure cryptosystem.

Claims

1. A method for a seamless cryptographic key system comprising the steps of:

encrypting digital data for transmission over a secure data link;

decrypting data from the secure data link;

seamlessly updating a cryptographic key for encrypting and decrypting said digital data; and

the step of seamlessly updating includes the step of loading said key variables into said cryptographic key generator by an interface means to control switch-over of said cryptographic key generator new key variables.

2. A method for a seamless cryptographic rekey system as claimed in claim 1, wherein said seamlessly updating the cryptographic key step further includes a step of using a cryptographic key generator.

3. A method for a seamless cryptographic rekey system as claimed in claim 2, wherein said step of using said cryptographic key generator further includes a step of providing key variables to said cryptographic key generator.

4. A method for a seamless cryptographic rekey system as claimed in claim 3, wherein the step of seamlessly updating said cryptographic key further includes the step of loading a switch-over value into a comparator to control said switch-over.

5. A method for a seamless cryptographic rekey system as claimed in claim 4, wherein the step of seamlessly updating said cryptographic key further includes the step of counting by a counter cryptographic key generator clock states.

6. A method for a seamless cryptographic rekey system as claimed in claim 5, wherein the step of seamlessly updating said cryptographic key includes the step of, switching a multiplexer for both an encrypting subsystem and a decrypting subsystem from the key variable to a new key variable when the counter reaches the specified state.

7. A method for a seamless cryptographic rekey system as claimed in claim 1, wherein the step of seamlessly updating said cryptographic key further includes the step of seamless updating the cryptographic key automatically by the encrypting and decrypting equipment.

8. An apparatus for a seamless cryptographic system comprising:

encryptor equipment for encrypting digital data for transmission over a data link;

decryptor equipment for decrypting digital data received from the data link;

a seamless cryptographic key generator for updating key variables for encrypting and decrypting said digital data; and

a key generator clock counter for counting states, said key generator clock counter coupled to said seamless cryptographic key generator.

9. An apparatus for a seamless cryptographic system as claimed in 8, wherein said seamless cryptographic key generator provides a cryptographic key for encrypting and decrypting said digital data.

10. An apparatus for a seamless cryptographic system as claimed in 8, wherein said cryptographic key includes a plurality of cryptographic key variables for encrypting and decrypting said digital data.

11. An apparatus for a seamless cryptographic system as claimed in 8, wherein the seamless cryptographic key generator includes updating interface means for loading said cryptographic key into said key generator clock counter.

12. An apparatus for a seamless cryptographic system as claimed in 11, wherein there is further included a switch-over register for storing switch-over values.

13. An apparatus for a seamless cryptographic system as claimed in 12, wherein there is further included a comparator to determine when the key generator clock counter reaches the specified switch over value, said comparator coupled to said switch-over register and coupled to said key generator clock counter.

14. An apparatus for a seamless cryptographic system as claimed in 13, wherein there is further included a multiplexer, said multiplexer for seamlessly switching the encryptor equipment and the decryptor equipment from a key variable to a new key variable, said multiplexer coupled to said comparator, said key generator and said plurality of cryptographic key variables.

15. An apparatus for a seamless cryptographic system as claimed in 14, wherein there is further included a Modulo 2 adder/exclusive-OR means for use in synchronization and resynchronization, said Modulo 2 adder/exclusive-OR function coupled to said key generator.

16. An apparatus for a seamless cryptographic system as claimed in 15, wherein there is further included a receive sync line for synchronization and resynchronization, said receive sync line coupled to said key generator and said key generator clock counter.