Method for secure key production

• US 5,720,034 A
• Filed: 12/07/1995
• Issued: 02/17/1998
• Est. Priority Date: 12/07/1995
• Status: Expired due to Term

• Current Assignee: Jeffrey D. Case
• Original Assignee: Jeffrey D. Case
• Inventors: Case, Jeffrey D.
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): LE, DIEU MINH T
• Application Number:
  US08/568,494
• Time in Patent Office: 803 Days
• Field of Search: 395/187.01, 395/186, 395/188.01, 395/726, 380/3, 380/4, 380/21, 380/23, 380/25, 380/30, 380/45, 380/49, 364/222.5, 364/286.4, 364/286.5, 364/260.81
• US Class Current: 380/283
• CPC Class Codes: H04L 9/0844 with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys
• CPC Class Codes: H04L 9/0869 involving random numbers or seeds

Abstract

A method for exchanging a secure slave key between an agent and a manager which are connected by an unsecured digital computer network. A master key is provided, which is known to both the manager and the agent. The manager sends a request for an unpredictable number across the digital computer network to the agent. The agent receives the request and generates the unpredictable number, which is sent back to the manager across the digital computer network. The manager receives the unpredictable number, and uses it and the master key to produce a slave key. The agent likewise uses the unpredictable number and the master key to produce the slave key. In this manner, identical slave keys have been produced at both of the manager and the agent sites, without having to send the slave key across the unsecured digital computer network.

Claims

1. A method of producing a secure slave key at each of an agent system and a manager system connected by an unsecured digital computer network comprising the steps of:

providing a master key which is known by both a manager and an agent,

sending a request for an unpredictable number from the manager to the agent using the digital computer network,

receiving the request for the unpredictable number at the agent,

generating the unpredictable number at the agent,

sending the unpredictable number from the agent to the manager using the digital computer network,

receiving the unpredictable number at the manager,

producing the slave key using the unpredictable number and the master key at the manager, and

producing the slave key using the unpredictable number and the master key at the agent.

2. The method of claim 1 wherein both of the steps of producing the slave key further comprise producing a slave key from the master key and the unpredictable number, using a one-way function.

3. The method of claim 1 wherein both of the steps of producing the slave key further comprise producing a slave key from the master key and the unpredictable string, using message digest algorithm five.

4. The method of claim 1 wherein the step of generating an unpredictable number further comprises generating an unpredictable number using information supplied at least in part by the manager.

5. The method of claim 1 wherein the manager and the agent are subsystems of the same system.

6. A method of producing a secure slave key at each of an agent system and a manager system connected by an unsecured digital computer network comprising the steps of:

providing a master key which is known by both a manager and an agent,

sending a request for an unpredictable number from the manager to the agent using the digital computer network,

receiving the request for the unpredictable number at the agent,

generating the unpredictable number at the agent,

sending the unpredictable number from the agent to the manager using the digital computer network,

receiving the unpredictable number at the manager,

producing the slave key using the unpredictable number and the master key at the manager,

producing the slave key using the unpredictable number and the master key at the agent,

transforming the slave key using an invertible function and a desired slave key to produce a delta slave key at the manager,

sending the delta slave key from the manager to the agent using the digital computer network,

receiving the delta slave key at the agent, and

transforming the slave key using the invertible function and the delta slave key to produce the desired slave key at the agent.

7. A method of exchanging information between a first computer and a second computer connected by an unsecured digital computer network comprising the steps of:

a) providing a master key which is known by both the first computer and the second computer,

b) sending a request for an unpredictable number from the first computer to the second computer via the unsecured digital computer network,

c) receiving the request for the unpredictable number at the second computer,

d) generating the unpredictable number at the second computer,

e) sending the unpredictable number from the second computer to the first computer via the unsecured digital computer network,

f) receiving the unpredictable number at the first computer,

g) producing the slave key using the unpredictable number and the master key at the first computer,

h) producing the slave key using the unpredictable number and the master key at the second computer,

i) encoding at least a portion of the information in the second computer using the slave key,

j) sending the encoded information from the second computer to the first computer via the unsecured digital computer network,

k) receiving the encoded information at the first computer, and

decoding the encoded information in the first computer using the slave key.

8. The method of claim 7 wherein both of the steps of producing the slave key further comprise producing the slave key from the master key and the unpredictable number, using a one-way function.

9. The method of claim 7 wherein both of the steps of producing the slave key further comprise producing the slave key from the master key and the unpredictable number, using message digest algorithm five.

10. The method of claim 7 wherein the step of generating the unpredictable number further comprises generating the unpredictable number using information supplied at least in part by the first computer.

11. The method of claim 7 wherein the step of encoding the information further comprises encoding the information using the slave key and an invertible function.

12. The method of claim 7 wherein the step of encoding the information further comprises encoding the information using the slave key and an XOR function.

13. The method of claim 7 wherein the first computer and the second computer are the same computer.

14. A method of exchanging information between a first computer and a second computer connected by an unsecured digital computer network comprising the steps of:

a) providing a master key which is known by both the first computer and the second computer,

b) sending a request for an unpredictable number from the first computer to the second computer via the unsecured digital computer network,

c) receiving the request for the unpredictable number at the second computer,

d) generating the unpredictable number at the second computer,

e) sending the unpredictable number from the second computer to the first computer via the unsecured digital computer network,

f) receiving the unpredictable number at the first computer,

g) producing the slave key using the unpredictable number and the master key at the first computer,

h) producing the slave key using the unpredictable number and the master key at the second computer,

i) transforming the slave key using an invertible function and a desired slave key to produce a delta slave key at the first computer,

j) sending the delta slave key from the first computer to the second computer using the digital computer network,

k) receiving the delta slave key at the second computer,

l) transforming the slave key using the invertible function and the delta slave key to produce the desired slave key at the second computer,

m) using the desired slave key in place of the slave key for the subsequent steps of the method,

n) encoding at least a portion of the information in the second computer using the slave key,

o) sending the encoded information from the second computer to the first computer via the unsecured digital computer network,

p) receiving the encoded information at the first computer, and

q) decoding the encoded information in the first computer using the slave key.

15. The method of claim 14 further comprising the addition of the following steps after step (1):

l1) encoding, sending, receiving, and decoding only a portion of the information per steps (i) through (l),

l2) repeating steps (h1) through (h5) at least once to produce a new desired slave key, and

l3) performing steps (i) through (l) on at least a portion of the information not previously processed per steps (i) through (l), using the new desired slave key.

16. The method of claim 15 further comprising repeating steps (l1) through (l3) to produce additional desired slave keys, and using the additional desired slave keys in performing steps (i) through (l) until all of the information has been processed per steps (i) through (l).

17. A method of exchanging information comprising the steps of:

a) providing a manager residing on a computer,

b) providing an agent residing on a computer,

c) providing a digital computer network between the manager and the agent,

d) providing a master key which is known by both the manager and the agent,

e) sending a request for an unpredictable number from the manager to the agent via the digital computer network,

f) receiving the request for the unpredictable number at the agent,

g) generating the unpredictable number at the agent,

h) sending the unpredictable number from the agent to the manager via the digital computer network,

i) receiving the unpredictable number at the manager,

j) producing the slave key using the unpredictable number and the master key at the manager,

k) producing the slave key using the unpredictable number and the master key at the agent,

l) encoding at least a portion of the information in the agent using the slave key,

m) sending the encoded information from the agent to the manager via the digital computer network,

n) receiving the encoded information at the manager, and

o) decoding the encoded information in the manager using the slave key.

18. The method of claim 17 wherein steps (a) and (b) further comprise providing the agent and the manager on the same computer.

19. The method of claim 17 wherein steps (a) and (b) further comprise providing the agent and the manager on different computers.

20. The method of claim 17 wherein step (c) further comprises providing an external digital computer network between the manager and the agent.

21. The method of claim 17 wherein step (c) further comprises providing an internal digital computer network between the manager and the agent.