Securing a link between two devices

• US 20060224892A1
• Filed: 04/04/2005
• Published: 10/05/2006
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Adams, Neil, Brown, Michael S., Little, Herb, Brown, Michael K., Davis, Dinah, McCallum, Michael
• Granted Patent: US 9,143,323 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• 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

Abstract

A cryptographic key is used to secure a communication link between a first device and a second device. Generating the cryptographic key is accomplished by a) generating a first cryptographic key, b) generating a second cryptographic key, c) applying a hash function to packets transmitted over the communication link to create a hash result, and d) applying the hash function to the first cryptographic key, the second cryptographic key and the hash result.

Claims

1. A method for securing a communication link between a first device and a second device, the method comprising:

generating a first cryptographic key;

generating a second cryptographic key;

applying a hash function to packets communicated over said communication link to create a hash result; and

applying said hash function to said first cryptographic key, said second cryptographic key and said hash result to generate a third cryptographic key to be used to secure said communication link.

2. The method of claim 1, wherein said packets were communicated over said communication link during generation of said first cryptographic key and during generation of said second cryptographic key.

3. The method of claim 1, wherein generating said first cryptographic key includes an exchange of public keys between said first device and said second device over said communication link, said public keys based on a secret shared by said first device and said second device.

4. The method of claim 1, wherein generating said second cryptographic key includes an exchange of public keys between said first device and said second device over said communication link.

5. The method of claim 1, wherein generating said first cryptographic key includes:

applying a function to a secret to obtain a generator element of a mathematical group;

raising said generator element to a first random number to obtain another element of said group;

sending said other element over said communication link;

receiving over said communication link a further element of said group, said further element having been created by raising said generator element to a second random number; and

raising said further element to said first random number to obtain said first cryptographic key.

6. The method of claim 1, wherein generating said second cryptographic key includes:

raising a known generator element of a mathematical group to a first random number to obtain another element of said group;

sending said other element over said communication link;

receiving over said communication link a further element of said group, said further element having been created by raising said known generator element to a second random number; and

raising said further element to said first random number to obtain said second cryptographic key.

7. A device comprising:

a communication interface through which said device is able to establish a communication link with another device;

a processor; and

a memory able to store executable code which, when executed by said processor, generates a first cryptographic key, generates a second cryptographic key, applies a hash function to packets communicated over said communication link to create a hash result, and applies said hash function to said first cryptographic key, said second cryptographic key and said hash result to generate a third cryptographic key.

8. The device of claim 7, wherein said packets were communicated over said communication link during generation of said first cryptographic key and during generation of said second cryptographic key.

9. A system comprising:

a first device and a second device able to communicate over a communication link, wherein said first device and said second device are each to generate a cryptographic key from a first cryptographic key, a second cryptographic key and a hash result created by hashing packets communicated over said communication link.

10. The system of claim 9, wherein said first device and said second device are to share a secret and said first cryptographic key is based upon said secret.

11. The system of claim 9, wherein said first device and said second device are to generate said first cryptographic key from an exchange of public keys over said communication link.

12. The system of claim 9, wherein said first device and said second device are to generate said second cryptographic key from an exchange of public keys over said communication link.