Browse Prior Art Database

VARYING ENCRYPTION KEYS FOR A SINGLE CALL

IP.com Disclosure Number: IPCOM000007360D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-19
Document File: 2 page(s) / 90K

Publishing Venue

Motorola

Related People

Thomas McGovern: AUTHOR

Abstract

The research into developing faster microproces- sors may pose a threat to encrypted communica- tions. As faster microprocessors are developed, means of "breaking" encryption Key Variables (i.e. by exhaustive search methods) will be accomplished with relative speed, thus providing less secure means of communication. Providing a means ofvarying the encryption Key Variables throughout a call elimi- nates this possibility of "breaking" all the Key Vari- ables in a useful time lapse.

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MO7VROl.A Technical Developments Volume 24 March 1995

VARYING ENCRYPTION KEYS FOR A SINGLE CALL

by Thomas McGovern

every .S seconds and a Key Variable was not used more than once, a majority of the Key Variables would be necessary to interpret any uselG1 voice infor- mation from the call.

1. INTRODUCTION

  The research into developing faster microproces- sors may pose a threat to encrypted communica- tions. As faster microprocessors are developed, means of "breaking" encryption Key Variables (i.e. by exhaustive search methods) will be accomplished with relative speed, thus providing less secure means of communication. Providing a means ofvarying the encryption Key Variables throughout a call elimi- nates this possibility of "breaking" all the Key Vari- ables in a useful time lapse.

  If it is believed that an exhaustive search may find a Key Variable in a usetirl time lapse, the next step to combating the problem may be to use multi- ple Key Variables during a given call. For example, consider a highly sensitive voice call which is 8 sec- onds in duration. If the Key Variable was changed

2. SOLUTION

  Given our path into digital communications, implementing a varying KeyId/Key Variable encryption technique with relative ease is possible. Currently, our Astro protocol sends out the KeyId at the beginning of a call, in a preamble, and is repeated every 360 msecs in alternating Logical Data Units (LDU). See Figure 1. Modifying this protocol would not be necessary to implement this invention in our Astro products. This invention could be implemented in any digital protocol that accommo- dates encryption.

PREAMBLE LDUl LDUZ LDUI LDU2 LDUl LDU2

Figure 1. Generic LDU fo...