ADAPTIVELY CONFIGURING THE VALIDATION TIMEOUT OF A SESSION KEY USED FOR SECURING COMMUNICATION WITH AN IMPLANTABLE MEDICAL DEVICE

• US 20120271380A1
• Filed: 04/13/2012
• Published: 10/25/2012
• Est. Priority Date: 04/20/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Roberts, Earle T., Ali, Irfan Z., Villalta, Donald L.
• Granted Patent: US 8,868,201 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: A61N 1/37254 Pacemaker or defibrillator security, e.g. to prevent or inhibit programming alterations by hackers or unauthorised individuals
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 2209/88 Medical equipments
• CPC Class Codes: H04L 63/0435 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 Class Codes: H04L 63/068 using time-dependent keys, e.g. periodically changing keys cryptographic mechanisms or cryptographic arrangements for controlling usage of secret information H04L9/088
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04W 12/041 Key generation or derivation

Abstract

Methods, devices and systems are disclosed that provide for dynamically adjusting the valid lifespan of a session key for wireless communication sessions established between at least two medical devices. Adjusting the session key lifetime balances protecting the communications link so that it is not unnecessarily susceptible to eavesdropping by third parties or other interference while obviating the need for a user to repeatedly perform access control steps.

Claims

1. A method for adjusting a timeout period of a communication session, comprising:

establishing a communication session between an implantable medical device and at least one other device, wherein a session key is transmitted between the implantable medical device and the at least one other device in establishing the communication session, the session key allowing one or both of programming of the implantable medical device by the at least one other device and decryption of information transmitted between the implantable medical device and the at least one other device during the communication session;

setting a time period interval of the session key;

receiving a communication session close trigger event;

performing a count of the time period interval based on the reception of the communication session close trigger event; and

disabling the session key in response to expiration of the time period count, wherein establishing, setting, receiving, performing, and disabling are each performed at least in part by one or both of the implantable medical device and the at least one other device.

2. The method of claim 1, wherein the time period interval is set before the session key is transmitted between the implantable medical device and the at least one other device in establishing the communication session.

3. The method of claim 1, further comprising evaluating a time duration for each of a plurality of previous communication sessions involving at least one of the implantable medical device and the at least one other device, wherein the time period interval of the session key is set based on the evaluation of the time duration for each of the plurality of previous communication sessions.

4. The method of claim 1, wherein setting the duration of the time period comprises evaluating at least one predefined criteria to determine the time period.

5. The method of claim 4, wherein the predefined criteria includes a category of a clinical procedure indicated to be performed as part of the communication session.

6. The method of claim 1, wherein setting the duration of the time period comprises receiving a predetermined time period input from the at least one other device, the at least one other device being a programmer configured to communicate with the implantable medical device.

7. The method of claim 1, wherein establishing the communication session comprises generating the session key, wherein the session key is generated by the at least one other device and is ephemeral.

8. The method of claim 1, wherein disabling the session key comprises deleting the session key from the device to which it was transmitted.

9. The method of claim 1, further comprising:

receiving an indication of activity during the time period count; and

resetting the time period count responsive to receiving the indication of activity.

10. The method of claim 1, wherein the trigger event comprises one of an inactivity interval, a session link loss indication, a close service request, expiration of a predefined interval, and a communication session interruption.

11. The method of claim 1, wherein the time period count is performed by the device of the plurality of devices to which the session key was transmitted.

12. The method of claim 1, further comprising generating an alert to a user based on the count of the time period interval.

13. A system for adjusting a timeout period of a communication session in transcutaneous communications, comprising:

an implantable medical device having communication circuitry;

an external device having communication circuitry, the communication circuitry of the implantable medical device and the communication circuitry of the external device configured to establish a communication session between the implantable medical device and the external device and to transmit a session key between the communication circuitry of the implantable medical device and the communication circuitry of the external device in establishing the communication session, the session key allowing one or both of programming of the implantable medical device by the external device and decryption of information transmitted between the implantable medical device and the external device during the communication session; and

control circuitry configured to set a time period interval of the session key, receive a communication session close trigger event, perform a count of the time period interval based on the reception of the communication session close trigger event, and disable the session key in response to expiration of the time period count.

14. The system of claim 13, wherein the control circuitry is further configured to evaluate a time duration for each of a plurality of previous communication sessions involving at least one of the implanted medical device and the external device, wherein the time period interval of the session key is set based on the evaluation of the time duration for each of the plurality of previous communication sessions.

15. The system of claim 13, wherein the control circuitry is configured to evaluate at least one criterion and set the duration of the time period based on the evaluation of the at least one criterion.

16. The system of claim 15, wherein the control circuitry is configured to receive an indication that establishment of the communication session is desired by a user, wherein the evaluation of the at least one criteria determines a category of a clinical procedure and the control circuitry sets the duration of the time period based on the category for the communication session.

17. The system of claim 13, wherein the control circuitry is distributed between the implantable medical device and the external device.

18. The system of claim 13, wherein the control circuitry is located entirely within a housing of the implantable medical device.

19. The system of claim 13, wherein the control circuitry is located entirely within a housing of the external device.

20. The system of claim 13, wherein the control circuitry is further configured to generate the session key as part of establishing the communication session and the session key is ephemeral.

21. The system of claim 13, wherein the control circuitry is configured to disable the session key by invalidating the session key for allowing one or both of programming of the implantable medical device by the external device and decryption of information transmitted between the implantable medical device and the external device during the communication session.

22. The system of claim 13, wherein the control circuitry is configured to receive an indication of communication activity during the time period count and reset the time period count responsive to receiving the indication of communication activity.

23. The system of claim 13, wherein the control circuitry is configured to generate a to a user based on the count of the time period interval.

24. A system for adjusting a timeout period of a communication session, comprising:

means for establishing a communication session between an implanted medical device and at least one other device, wherein a session key is transmitted between the implanted medical device and the at least one other device in establishing the communication session, the session key allowing one or both of programming of the implanted medical device by the at least one other device and decryption of information transmitted between the implanted medical device and the at least one other device during the communication session;

means for setting a time period interval of the session key;

means for receiving a communication session close trigger event;

means for performing a count of the time period interval based on the reception of the communication session close trigger event; and

means for disabling the session key in response to expiration of the time period count.

25. A computer readable medium comprising instructions for causing a medical device to adjust a timeout period of a communication session by performing steps comprising:

establishing a communication session between an implantable medical device and at least one other device, wherein a session key is transmitted between the implantable medical device and the at least one other device in establishing the communication session, the session key allowing one or both of programming of the implantable medical device by the at least one other device and decryption of information transmitted between the implantable medical device and the at least one other device during the communication session;

setting a time period interval of the session key;

receiving a communication session close trigger event;

performing a count of the time period interval based on the reception of the communication session close trigger event; and

disabling the session key in response to expiration of the time period count.