Encryption synchronization combined with encryption key identification

• US 5,185,796 A
• Filed: 05/30/1991
• Issued: 02/09/1993
• Est. Priority Date: 05/30/1991
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Wilson, Alan L.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/707,487
• Time in Patent Office: 621 Days
• Field of Search: 380/21, 380/48, 380/49
• US Class Current: 380/277
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms

Abstract

In an encrypted radio system, transmsitters and receivers can each be provided with a plurality of encryption algorithms (407 and 425) and/or encryption key variables (408 and 426). A unique logical ID (409 and 427) corresponds to each of the above. During transmission of an encrypted message, both encryption synchronization information (319) and information concerning the logical ID (318) is repetitively interleaved with the encrypted message itself. So configured, a receiver that temporarily loses viable reception can again obtain encryption synchronization and algorithm/key information, and therefore rapidly recover from the reception disturbance.

Claims

1. A method of transmitting system encryption information in conjunction with message information, comprising the steps of:

A) selecting at least an encryption key and an encryption algorithm;

B) encrypting at least a part of the message information using the encryption key and the encryption algorithm;

C) automatically transmitting repetitively, interleaved with the message information, identifying information for the encryption key.

2. The method of claim 1, wherein the step of transmitting further includes the step of also automatically repetitively transmitting identifying information for the encryption algorithm.

3. The method of claim 2, wherein the step of transmitting further includes the step of also automatically transmitting encryption synchronization information.

4. The method of claim 1, wherein the message information comprises a series of bits.

5. The method of claim 4, wherein the series of bits are encrypted as a function of the encryption key and the encryption algorithm.

6. The method of claim 1, wherein the step of transmitting further includes the step of also automatically transmitting encryption synchronization information.

7. The method of claim 1, wherein the step of selecting further includes the step of automatically selecting an encryption key from amongst a plurality of encryption keys.

8. A method of transmitting system encryption information in conjunction with message information, comprising the steps of:

A) selecting at least an encryption key and an encryption algorithm;

B) forming a packet comprised of encryption synchronizing information and information identifying;

i) the encryption key; and

ii) the encryption algorithm;

C) encrypting at least a part of the message information using the encryption key and the encryption algorithm;

D) automatically repetitively transmitting the packet in an information field that is interleaved with the message information.

9. The method of claim 8, wherein the message information comprises a series of bits.

10. The method of claim 9, wherein the series of bits are encrypted as a function of the encryption key and the encryption algorithm.

11. A method of transmitting system encryption information in conjunction with message information, comprising the steps of:

A) selecting at least an encryption key and an encryption algorithm;

B) forming an encryption information packet comprised of key ID information and encryption synchronizing information, wherein the key ID information identifies both the encryption key and the encryption algorithm;

C) encrypting at least a part of the message information using the encryption key and the encryption algorithm;

D) automatically repetitively transmitting the encryption information packet in an information field that is interleaved with the message information.

12. The method of claim 11, wherein the step of repetitively transmitting further includes the step of automatically transmitting a plurality of session data units, wherein each of the session data units includes at least one of the encryption information packets.

13. The method of claim 12, wherein each of the session data units is comprised of two data frames.

14. The method of claim 13, wherein the data frames are each comprised of a plurality of data packets, and wherein at least one of the data packets comprises an encryption information packet.

15. A radio, comprising:

A) message processing means for providing a digitized message to be transmitted;

B) first memory means for storing a plurality of encryption keys;

C) second memory means for storing a plurality of key IDs, wherein each one of the key IDs corresponds to a particular one of the plurality of encryption keys;

D) selection means for selecting a particular one of the encryption keys;

E) encryption means operably coupled to the message processing means, the first memory means, and the selection means, for processing the digitized message to be transmitted as a function of the particular encryption key and providing an encrypted message;

F) transmitter means operably coupled to the second memory means and the encryption means for transmitting;

i) the encrypted message; and

ii) the key ID that corresponds to the encryption key then in use;

such that the key ID is repetitively transmitted while interleaved with the encrypted message.

16. The radio of claim 15, and further comprising:

G) encryption synchronization means for providing an encryption sync signal to the transmitter means, such that the transmitter means further transmits the encryption sync signal in conjunction with transmission of the key ID.

17. The radio of claim 16, and further comprising:

H) third memory means operably coupled to the encryption means for storing a plurality of encryption algorithms and for providing such encryption algorithms to the encryption means for use thereby.

18. The radio of claim 17, wherein the key ID represents both the encryption key then in use and the encryption algorithm then in use.