Efficient key derivation with forward secrecy

Patent metadata

Field	Value
Publication number	US-2016352706-A1
Application number	US-201514724315-A
Country	US
Kind code	A1
Filing date	May 28, 2015
Priority date	May 28, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

Various embodiments relate to a method, device, and non-transitory medium including: determining a master key value for use in secure communications with a different device, wherein the master key value is used as a master key; deriving at least one session key using the master key; generating a new master key value based on the master key; deleting the current master key value; and using the new master key value as the master key.

First claim

What is claimed is:

1 . A non-transitory machine-readable medium encoded with instructions for execution by a processor, the non-transitory machine-readable medium comprising:
instructions for determining a master key value for use in secure communications with a different device, wherein the master key value is used as a master key; instructions for deriving a session key using the master key; instructions for generating a new master key value based on the master key; instructions for deleting the current master key value; and instructions for using the new master key value as the master key.

2 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for generating a new master key value based on the master key comprise:
instructions for combining the session key with at least one additional session key derived using the master key to form the new master key value.

3 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for generating a new master key value based on the master key comprise:
instructions for combining the current master key value with at least the session key to form the new master key.

4 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for generating a new master key value comprise instructions for encrypting a constant value using the master key.

5 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for generating a new master key value comprise instructions for applying an XOR function to two or more cryptographic keys.

6 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for deriving at least one session key using the master key comprise:
instructions for encrypting at least one constant value using the master key.

7 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for deriving at least one session key using the master key comprise:
instructions for combining the current value of the master key with the new value of the master key to produce a session key.

8 . The non-transitory machine-readable medium of claim 1 , further comprising instructions for periodically re-executing the instructions for generating a new master key.

9 . The non-transitory machine-readable medium of claim 1 , wherein the instructions for negotiating a master key value with a different device comprise instructions for negotiating with a secure element that is part of the same device as the processor.

10 . The non-transitory machine-readable medium of claim 1 , wherein the non-transitory machine-readable medium is encoded with instructions for execution by a secure element within a host device.

11 . A device for participating in a secure communication session, the device comprising:
a memory; an interface to another device with which secure communication will occur; and a processor in communication with the interface and memory, the processor being configured to
determine a master key value for use in secure communications with a different device, wherein the master key value is used as a master key,
derive a session key using the master key,
generate a new master key value based on the master key,
delete the current master key value, and
use the new master key value as the master key.

12 . The device of claim 11 , wherein in generating a new master key value based on the master key, the processor is configured to:
combine the session key with at least one additional session key derived using the master key to form the new master key value.

13 . The device of claim 11 , wherein in generating a new master key value based on the master key, the processor is configured to:
combine the current master key value with at least the session key to form the new master key.

14 . The device of claim 11 , wherein in generating a new master key value, the processor is configured to encrypt a constant value using the master key.

15 . The device of claim 11 , wherein in generating a new master key value, the processor is configured to apply an XOR function to two or more cryptographic keys.

16 . The device of claim 11 , wherein in deriving at least one session key using the master key the, processor is configured to:
encrypt at least one constant value using the master key.

17 . The device of claim 11 , wherein in deriving at least one session key using the master key, the processor is configured to:
combine the current value of the master key with the new value of the master key to produce a session key.

18 . The device of claim 11 , wherein the processor is further configured to periodically re-execute the step generating a new master key.

19 . The device of claim 11 , further comprising a secure element, wherein the secure element is the other device with which secure communication will occur.

20 . The device of claim 11 , wherein the device is a secure element to be installed in a host system, wherein the host system is the other device with which secure communication will occur.

Assignees

• Nxp Bv

Inventors

• Peeters Michael Michel Patrick
• Verslegers Rudi
• Warnez Dimitri

Classifications

• H04L63/062

  for key distribution, e.g. centrally by trusted party (cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819) · CPC title

• H04L63/061 Primary

  for key exchange, e.g. in peer-to-peer networks (cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838) · CPC title

• H04L9/0861 Primary

  Generation of secret information including derivation or calculation of cryptographic keys or passwords · CPC title

• H04L9/0816 Primary

  Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use · CPC title