US 5,517,567 A · Key distribution system

Abstract

A system for securely distributing a communications key from a master unit to a remote unit for use in cryptographic communications between the master and remote units employs first and second secret numbers stored in both the master and remote units, and a random number generated in the master unit which is combined with the first secret number to produce a first intermediate number which is in turn combined with the second secret number to produce a second intermediate number. The second intermediate number is combined with the communications key to produce a transmission number sent with the random number to the remote unit. The remote unit, using the random number, the transmission number, and the first and second secret numbers, is able to reproduce the communications key. A method for securely distributing the communications key from the master unit to the remote unit is also provided along with a system and method for authenticating the identity of any one of a plurality of remote units in communication with the master unit, whereby each remote unit stores first and second secret numbers unique to it, all of which secret numbers are also stored in the master unit.

Claims31

Dependent claims

A system for securely distributing a communications key from a master unit to a remote unit, comprising:

memory means for storing first and second secret numbers in the master unit;
random number generating means for providing a random number to the master unit;
first combining means in the master unit for combining said random number with said first secret number to produce a first intermediate number;
second combining means in the master unit for combining said first intermediate number with said second secret number to produce a second intermediate number;
third combining means in the master unit for combining said second intermediate number with the communications key to produce a transmission number;
communication means for transmitting signals between the master and remote units;
memory means for storing said first and second secret numbers in the remote unit;
first combining means in the remote unit for combining said random number with said first secret number to produce said first intermediate number;
second combining means in the remote unit for combining said first intermediate number with said second secret number to produce said second intermediate number;
and
third combining means in the remote unit for combining said intermediate number with said transmission number to produce the communications key.

8 more elements

A method for authenticating the identity of remote unit in a plurality of remote units in communication with a master unit, said method comprising the steps of:

(a) storing in each one of the plurality of remote units first and second secret numbers, said first and second secret numbers in one remote unit being different than said first and second secret numbers in any other remote unit;
(b) storing in the master unit said first and second secret numbers of the plurality of the remote units;
(c) establishing initial contact between the master unit and a selected one of the plurality of remote units;
(d) providing a random number to the master unit;
(e) transmitting said random number from the master unit to said selected remote unit;
(f) processing said random number in said selected remote unit with said first and second secret numbers stored in said selected remote unit to generate a remote processed number;
(g) processing said random number in the master unit with said first and second secret numbers to generate a master processed number;
(h) transmitting said remote processed number to the master unit;
and
(i) comparing said remote processed number and said master processed number in the master unit, whereby the identity of said selected remote unit is authenticated when said remote processed number is equal to said master processed number.

7 more elements

A system for authenticating the identity of a remote unit in a plurality of remote units in communication with a master unit, comprising:

remote memory means for storing in each one of the plurality of remote units first and second secret numbers, said first and second secret numbers in one remote unit being different than said first and second secret numbers in any other remote unit;
master memory means for storing in the master unit said first and second secret numbers of the plurality of the remote units;
contact means for establishing initial communication between the master unit and a selected one of the plurality of said remote units;
random number generating means for providing a random number to the master unit;
communications means for transmitting signals between the master and remote units;
remote processing means for combining said random number in said selected remote unit with said first and second secret numbers stored in said selected remote unit in said predetermined manner to generate a remote processed number;
master processing means for processing said random number in the master unit with said first and second secret numbers for said selected remote unit stored in the master unit in said predetermined manner to generate a master processed number;
and
comparison means for comparing said remote processed number and said master processed number in the master unit, whereby the identity of said selected remote unit is authenticated when said remote processed number is equal to said master processed number.

6 more elements

Dependencies are inferred from the claim text.

Key distribution system

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Key distribution system

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Abstract

Claims31