System and method for generating reproducible session keys

• US 20050254658A1
• Filed: 02/16/2005
• Published: 11/17/2005
• Est. Priority Date: 05/03/2004
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Brown, Michael S., Brown, Michael K., Little, Herbert A.
• Granted Patent: US 7,929,702 B2
• Time in Patent Office: Days
• US Class Current: 380/286
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords

Abstract

A system and method for generating reproducible session keys in a wireless messaging system. The session key is generated based on a hash of a message itself, optionally concatenated with additional information. Since the local server stores the message, it can easily regenerate the same session key in response to each MORE request. The method of the invention can be implemented with the stored original message, a public key, and an algorithm for generating the session key based on a hash of the message.

Claims

1. A method of generating a reproducible session key for encrypting data in a data item for transmission to a remote communication device during a session, wherein if the data item exceeds a selected batch size a plurality of batches of data are transmitted during the session and encrypted with the same session key, comprising the steps of:

a. storing the data item in at least one memory addressable by a data processing device, and

b. applying a deterministic algorithm to all or a portion of the data item to generate a hash of the data item for use as a unique session key associated with the data item.

2. The method of claim 1 wherein the deterministic algorithm comprises a hash algorithm.

3. The method of claim 1 wherein the deterministic algorithm comprises a key derivation function.

4. The method of claim 1 comprising the additional step, after step a., of concatenating the portion of the data item with additional data.

5. The method of claim 4 wherein the additional data is from a source external to the data item.

6. The method of claim 1 comprising the additional step of c. applying a public key to the session key to generate an encrypted session key.

12. The system of claim 1 wherein the processor further applies a public key to the session key to generate an encrypted session key.

7. A system for generating a reproducible session key for encrypting data in a data item for transmission to a remote communication device during a session, wherein if the data item exceeds a selected batch size a plurality of batches of data are transmitted during the session and encrypted with the same session key, comprising a data processing device in communication with at least one memory for storing the data item and comprising a processor for applying a deterministic algorithm to all or a portion of the data item to generate a hash of the data item for use as a unique session key associated with the data item.

8. The system of claim 7 wherein the deterministic algorithm comprises a hash algorithm.

9. The system of claim 7 wherein the deterministic algorithm comprises a key derivation function.

10. The system of claim 7 wherein the processor further concatenates the portion of the data item with additional data.

11. The system of claim 10 wherein the additional data is from a source external to the data item.

13. A computer program product for use with a computer, the computer program product comprising a computer usable medium having computer readable program code means embodied in said medium for generating a reproducible session key for encrypting message data, said computer program product having a. computer readable program code means for reading the data item from at least one memory, and b. computer readable program code means for applying a deterministic algorithm to all or a portion of the data item to generate a hash of the data item for use as a unique session key associated with the data item.

14. The computer program product of claim 13 wherein the deterministic algorithm comprises a hash algorithm.

15. The computer program product of claim 13 wherein the deterministic algorithm comprises a key derivation function.

16. The computer program product of claim 13 comprises computer readable program code means for concatenating the portion of the data item with additional data.

17. The computer program product of claim 16 wherein the additional data is from a source external to the data item.

18. The computer program product of claim 13 comprising computer readable program code means for applying a public key to the session key to generate an encrypted session key.