Secure telemetric link

• US 9,960,916 B2
• Filed: 09/04/2012
• Issued: 05/01/2018
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Corndorf, Eric D.
• Primary Examiner(s): Desrosiers, Evans
• Application Number:
  US13/602,427
• Publication Number:
  US 20120330380A1
• Time in Patent Office: 2,065 Days
• Field of Search: 713168-174, 713182-186, 713202, 709225, 709229, 726 2- 6
• CPC Class Codes: G06F 7/582 Pseudo-random number generators
• 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 9/0631 Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms
• CPC Class Codes: H04L 9/0637 Modes of operation, e.g. cipher block chaining [CBC], electronic codebook [ECB] or Galois/counter mode [GCM]
• 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
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853

Abstract

A communications protocol is used to provide data privacy, message integrity, message freshness, and user authentication to telemetric traffic, such as to and from implantable medical devices in a body area network. In certain embodiments, encryption, message integrity, and message freshness are provided through use of token-like nonces and ephemeral session-keys derived from device identification numbers and pseudorandom numbers.

Claims

1. A medical device adapted for implantation comprising:

a memory configured to store a key used to secure communications within a wireless network;

a transceiver module configured to wirelessly communicate with another device within the wireless network; and

a sensor configured to detect close proximity of the other device;

wherein the medical device is configured to transmit the key wirelessly in response to the sensor detecting close proximity of the other device,

wherein the medical device is configured to be in a locked state in which the medical device does not transmit the key in response to the sensor detecting close proximity of the other device and to transition to an unlocked state in response to a request from the other device, and

wherein in the unlocked state the medical device does transmit the key in response to the sensor detecting close proximity of the other device.

2. The medical device of claim 1, wherein the sensor comprises a near-field magnetic sensor configured to detect the presence of a magnet and the medical device is configured to transmit the key wirelessly in response to the near-field magnetic sensor detecting the magnet.

3. The medical device of claim 2, wherein the near-field magnetic sensor comprises one of a magnetic reed switch and Hall-effect sensor.

4. The medical device of claim 1, wherein the key may be a temporary key that is only valid for the duration of a telemetry session.

5. The medical device of claim 1, wherein the key comprises a first key and the memory is configured to store a second, temporary key, wherein the medical device is configured to require additional credentials to transmit the first key compared to the credentials to transmit the second, temporary key.

6. The medical device of claim 5, wherein the medical device is configured to transmit the second, temporary key in response the sensor detecting close proximity of the other device for a first period of time and to transmit the first key in response the sensor detecting close proximity of the other device for a second period of time, wherein the second period of time is longer than the first period of time.

7. The medical device of claim 1, wherein the transceiver transmits the key at a reduced RF transmission power in response to the sensor detecting close proximity of the other device.

8. The medical device of claim 1, wherein the medical device transitions back to the locked state when the sensor does not detect close proximity of the other device within a predetermined period of time of transitioning to the unlocked state.

9. The medical device of claim 1, wherein the key comprises one of a network key and a session key.

10. A method comprising:

storing a key in a memory of a medical device, the key used to secure communications within a wireless network;

detecting close proximity of another device within the wireless network;

wirelessly transmitting the key to the other device in response to detecting close proximity of the other device, wherein wirelessly transmitting the key comprises;

operating in a locked state, wherein the key is not transmitted in response to detecting close proximity of the other device in the locked state; and

transitioning to an unlocked state in response to a request from the other device, wherein the key is transmitted in response to detecting close proximity of the other device when in the unlocked state.

11. The method of claim 10, wherein detecting close proximity of another device within the wireless network comprises detecting the presence of a magnet.

12. The method of claim 10, wherein wirelessly transmitting the key comprises wirelessly transmitting a temporary key that is only valid for the duration of a telemetry session.

13. The method of claim 10, wherein the key comprises a first key and the method further comprises:

storing a second, temporary key;

transmitting the first key in response to a first set of credentials; and

transmitting the second, temporary key in response to a second set of credentials, wherein the first set of credentials includes additional credentials to compared to the second set of credentials.

14. The method of claim 13, wherein the first set of credentials comprises detecting close proximity of the other device for a first period of time and the second set of credentials comprises detecting close proximity of the other device for a second period of time, wherein the first period of time is longer than the second period of time.

15. The method of claim 10, further comprising reducing the RF transmission power in response to detecting close proximity of the second device and transmitting the key at the reduced RF transmission power.

16. The method of claim 10, further comprising transitioning back to the locked state in response to not detecting close proximity of the other device within a predetermined period of time after transitioning to the unlocked state.

17. The method of claim 10, wherein the key is one of a network key or a session key.