System and method for secured host-slave communication

Patent metadata

Field	Value
Publication number	US-9231926-B2
Application number	US-201113308363-A
Country	US
Kind code	B2
Filing date	Nov 30, 2011
Priority date	Sep 8, 2011
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

A new system and method for communicating between a host device and one or more slave devices are presented. The system provides data error checking and correcting, data encryption, and robust slave address sequencing using a portion of a session key. The data encryption uses a second portion of the session key, which changes for each power cycle.

First claim

What is claimed is:

1. Slave device circuitry, comprising:
a processor and memory coupled thereto having stored therein program code instructions which, when executed by the processor, cause the processor to:
following the slave device circuitry being reset, determine a seed value;
receive a host number from a host that is substantially random;
generate a session key based upon the determined seed value and the host number, the session key being substantially random and a single session key;

perform encryption and decryption operations based on the generated session key on data to be transmitted and data received by the slave device circuitry, respectively; and
determine an address value based on the generated session key for a slave device associated with the slave device circuitry for communicating with the host,

wherein substantially random comprises being one of a true random number and a pseudorandom number,
wherein a first portion of the session key is used by the processor for performing the encryption and decryption operations on the data to be transmitted and the data received by the slave device circuitry, respectively, and a second portion of the session key is used for determining the address value for the slave device associated with the slave device circuitry for communicating with the host,
wherein the session key comprises a set of bits,
wherein the first portion of the session key comprises a first predetermined subset of the set of bits,
wherein the second portion of the session key comprises a second predetermined subset of the set of bits, and
wherein the first predetermined subset of the set of bits is separate from the second predetermined subset of the set of bits.

2. The slave device circuitry of claim 1 , wherein the processor calculates a session identifier value following the slave device circuitry being reset, the session identifier value being based upon a session identifier value prior to the slave device circuitry being reset, the session key being based upon the calculated session identifier value.

3. The slave device circuitry of claim 2 , wherein the calculated session identifier value is the session identifier value prior to the slave device circuitry being reset that is incremented or decremented.

4. The slave device circuitry of claim 2 , wherein the processor determines a substantially random number based only upon the determined seed value, the calculated session identifier value and a serial number of the slave device, and wherein the session key is based upon the substantially random number.

5. The slave device of circuitry of claim 2 , wherein the processor determines a substantially random number based upon a SHA-1 algorithm of the determined seed value, the calculated session identifier value and a serial number of the slave device; identifies a slave random number from a portion of the substantially random number; and determines the session key based upon a hash-based message authentication code (HMAC) of the host number received from the host, the slave random number, a secret encryption key of the slave device and the session identifier value, the session key being a substantially random number.

6. The slave device circuitry of claim 1 , wherein the determined seed value is determined using a secure hash algorithm.

7. The slave device circuitry of claim 1 , wherein the determined seed value is substantially random.

8. The slave device circuitry of claim 1 , wherein the session key is based upon a secret encryption key of the slave device.

9. The slave device circuitry of claim 1 , wherein the instructions which cause the processor to determine the session key use a hash-based message authentication code (HMAC).

10. The slave device circuitry of claim 1 , wherein the encryption and decryption operations form part of a stream cipher for communicating with the host.

11. The slave device circuitry of claim 1 , wherein the determined seed value is based upon a seed value of the slave device prior to the slave device circuitry being reset.

12. The slave device circuitry of claim 1 , wherein a toner bottle includes the slave device circuitry.

13. The slave device circuitry of claim 1 , wherein the processor functions as a pseudorandom number generator that is initialized with the second portion of the session key, and a portion of an output of the pseudorandom number generator forms a portion of the address value of the slave device.

14. A computer program product stored in a non-transitory storage medium and having instructions which when executed by a processor in a slave device causes the processor to:
following the slave device being reset, determine a seed value;
receive a host number from a host that is substantially random;
generate a session key based upon the determined seed value and the host number, the session key being substantially random and a single session key;
perform encryption and decryption operations based upon the generated session key on data to be transmitted and data received by the slave device, respectively; and
determine a new address value for the slave device for communicating with the host based upon the generated session key,
wherein substantially random comprises being one of a true random number and a pseudorandom number,
wherein a first portion of the session key is used to perform the encryption and decryption operations and a second portion of the session key is used to determine the new address value for the slave device for communicating with the host,
wherein the session key comprises a set of bits,
wherein the first portion of the session key comprises a first predetermined subset of the set of bits,
wherein the second portion of the session key comprises a second predetermined subset of the set of bits, and
wherein the first predetermined subset of the set of bits is separate from the second predetermined subset of the set of bits.

15. The computer program product of claim 14 , wherein the instructions cause the processor to calculate a session identifier value following the slave device being reset, the session identifier value being based upon a session identifier value prior to the slave device being reset, the session key being based upon the calculated session identifier value.

16. The computer program product of claim 15 , wherein the instructions cause the processor to determine a substantially random number based only upon the determined seed value, the calculated session identifier value and a serial number of the slave device, and wherein the session key is based upon the substantially random number.

17. The computer program product of claim 14 , wherein the determined seed value is determined using a hash algorithm.

18. The computer program product of claim 15 , wherein the instructions cause the processor to determine a substantially random number based upon a SHA-1 algorithm of the determined seed value, the calculated session identifier value and a serial number of the slave device, identify a slave random number from a portion of the substantially random number, and determine the session key based upon a hash-based message authentication code (HMAC) of the host number received from the host, the slave random number, a secret encryption key of the slave device and the session identifier value, the session key being a substantially random number.

19. The computer program product of claim 14 , wherein the determined seed value is substantially random.

20. The computer program product of claim 14 , wher

Assignees

• Adkins Christopher Alan
• Rademacher Timothy John
• Lexmark Int Inc

Inventors

• Adkins Christopher Alan
• Rademacher Timothy John

Classifications

• H04L9/0869

  involving random numbers or seeds · CPC title

• H04L63/0435 Primary

  wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06) · CPC title

• G06F2212/1052

  Security improvement · CPC title

• G06F12/1466

  Key-lock mechanism · CPC title

• H04L9/0866 Primary

  involving user or device identifiers, e.g. serial number, physical or biometrical information, DNA, hand-signature or measurable physical characteristics · CPC title