Key variable identification method

• US 5,247,576 A
• Filed: 02/27/1991
• Issued: 09/21/1993
• Est. Priority Date: 02/27/1991
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bright, Michael W.
• Primary Examiner(s): CAIN, DAVID C
• Application Number:
  US07/661,792
• Time in Patent Office: 937 Days
• Field of Search: 380/21, 380/23, 375/1
• US Class Current: 380/271
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0833 involving conference or group key network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065
• CPC Class Codes: H04L 9/16 the keys or algorithms being changed during operation

Abstract

In a communication system that includes a plurality of communication units, a communication resource allocator, and a limited number of transceivers that transceive information amongst the plurality of communication units via a limited number of communication resources, at least some of the information is transceived utilizing encryption means. To enhance the security of the communication system multiple keys are employed wherein a first communication unit transmits information identifying a particular key of the plurality of keys. Upon receiving the identifying information, at least a second communication unit looks up the particular key that is represented by the identifying information. Once the key is determined, it is loaded into a cryptographic circuit of the second communication unit enabling the second communication unit to receive encrypted messages from the first communication unit.

Claims

1. In a communication system that includes a communication resource allocator, a plurality of communication units, a limited number of transceivers that transceive information amongst the plurality of communication units via a limited number of communication resources, wherein at least some of the information is encrypted prior to transmission and subsequently decrypted upon reception by selected communication units of the plurality of communication units, a method for improving encryption and decryption of the at least some of the information, the method comprises the steps of:

a) transmitting, by a first communication unit of the plurality of communication units, information identifying one of a plurality of encryption codes to produce identifying information;

b) upon receipt of the identifying information by at least a second communication unit of the selected communication units, identifying the one of the plurality of encryption codes from the identifying information when the second communication unit contains the identifying information in an encryption code identifying database; and

c) when the second communication unit contains the identifying information in the encryption code identifying database, entering the one of the plurality of encryption codes in to a cryptographic circuit; and

d) disabling a mute circuit after the one of the plurality of encryption codes is entered in to the cryptographic circuit.

2. In a communication system that includes a communication resource allocator, a plurality of communication units, a limited number of transceivers that transceive information amongst the plurality of communication units via a limited number of communication resources, wherein at least some of the information is encrypted prior to transmission and subsequently decrypted upon reception by selected communication units of the plurality of communication units, a method for improving encryption and decryption of the at least some of the information, the method comprises the steps of:

a) transmitting, by a first communication unit of the plurality of communication units, information identifying one of a plurality of encryption codes to produce identifying information;

b) upon receipt of the identifying information by at least a second communication unit of the selected communication units, identifying the one of the plurality of encryption codes from the identifying information when the second communication unit contains the identifying information in an encryption code identifying database;

c) when the second communication unit contains the identifying information in the encryption code identifying database, entering the one of the plurality of encryption codes in to a cryptographic circuit; and

d) overriding a preselected encryption code of the plurality of encryption codes when entering the one of the encryption codes in to the cryptographic circuit.

3. The method of claim 2 further comprises, prior to overriding the preselected encryption code, storing the preselected encryption code.

4. The method of claim 3 further comprises transmitting, by the second communication unit during a predetermined transmit time, information to the first communication unit, wherein the information is encrypted per the one of the encryption codes.

5. The method of claim 4 further comprises entering the preselected encryption code in to the cryptographic circuit after the predetermined transmit time expires.

6. In the method of claim 3, step (c) further comprises entering the one of the plurality of encryption codes in to the cryptographic circuit for a predetermined receive time.

7. The method of claim 6 further comprises entering the preselected encryption code in to the cryptographic circuit when the predetermined received time expires.

8. In a communication system that includes a communication resource allocator, a plurality of communication units, a limited number of transceivers that transceive information amongst the plurality of communication units via a limited number of communication resources, wherein at least some of the information is encrypted prior to transmission and subsequently decrypted upon reception by selected communication units of the plurality of communication units, and wherein at least some of the communication units transmit information identifying one of a plurality of encryption codes prior to transmitting encryption information, each of the at least some of the plurality of communication units comprises:

identifying database means for storing identifying information of at least some of the plurality of encryption codes and the at least some of the plurality of encryption codes;

receiving means, operably associated with the identifying database means, for receiving identifying information;

transmitting means, operably associated with the identifying database means, for transmitting identifying information; and

timer means, operably associated with the identifying database means, for determining a predetermined receive time and a predetermined transmit time.