Method And System For Establishing Cryptographic Communications Between A Remote Device And A Medical Device

• US 20110170692A1
• Filed: 11/04/2010
• Published: 07/14/2011
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics International Ltd.
• Inventors: Troesch, Martin, Konrad, Guido, Linder, Felix, Kopf, Gregor
• Granted Patent: US 8,472,630 B2
• Time in Patent Office: Days
• US Class Current: 380/260
• CPC Class Codes: G06F 21/606 by securing the transmission between two devices or processes
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 2209/88 Medical equipments
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/06 for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04L 63/166 at the transport layer
• CPC Class Codes: H04L 9/002 Countermeasures against attacks on cryptographic mechanisms network architectures or network communication protocols for protection against malicious traffic H04L63/1441
• CPC Class Codes: H04L 9/006 involving public key infrastructure [PKI] trust models network architecture or network communication protocol for supporting authentication of entities using certificates in a packet data network H04L63/0823
• 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 9/30 Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy
• CPC Class Codes: H04L 9/302 involving the integer factorization problem, e.g. RSA or quadratic sieve [QS] schemes
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

A method and system establishing cryptographic communications between a remote device and a medical device, with the medical device having less processing power than the remote device are disclosed. The method may comprise establishing unencrypted communication between the remote device and the medical device, generating an asymmetric key pair by the remote device comprising a public key and a private key, generating a key request message and sending of the key request message together with the public key to the medical device, generating a pre-master key and encryption of the pre-master key with the received public key by the medical device, generating a key response message and sending of the key response message together with the encrypted pre-master key from the medical device to the remote device, decrypting the encrypted pre-master key with the private key by the remote device, and deriving a master key as a symmetric key from the pre-master key.

Claims

1. A method for establishing cryptographic communications between a remote device and a medical device, with the medical device having less processing power than the remote device, comprising:

establishing unencrypted communication between the remote device and the medical device;

generating an asymmetric key pair by the remote device, the asymmetric key pair comprising a public key and a private key;

generating a key request message by the remote device and sending of the key request message together with the public key to the medical device;

generating a pre-master key by the medical device and encryption of the pre-master key with the received public key by the medical device;

generating a key response message by the medical device and sending of the key response message together with the encrypted pre-master key from the medical device to the remote device;

decrypting the encrypted pre-master key with the private key by the remote device; and

deriving a master key as symmetric key from the pre-master key by either using the pre-master key as master key or by using the key request message or the key response message for the derivation of the master key from the pre-master key by each of the medical device and the remote device, the master key to be used for both decryption and encryption of application data to be communicated, wherein the key request message and/or the key response message contain random data and a time stamp.

2. The method of claim 1, wherein the medical device is an insulin pump.

3. The method of claim 1, wherein the assymetric key pair is an RSA key pair.

4. The method of claim 1, wherein the key request key request message or the key response message contain random data and a time stamp.

5. The method of claim 1, wherein the remote device and the medical device each compute verification data using the master key and each display the computed verification data to a user, and wherein communication of the application data may first start after the user has confirmed that the verification data computed by the remote device and the medical device have the same values.

6. The method of claim 5, wherein the key request message and/or the key response message contain a session identifier.

7. The method of claim 6, wherein requesting resuming of a previous session the key request message that the remote device sends to the medical device contains the session identifier of the session that shall be resumed.

8. The method of claim 7, wherein receipt of a key request message with a session identifier the medical device has the option of accepting or declining the request to resume the session identified by the session identifier.

9. The method of claim 8, wherein a validity time period is defined after a request to resume a session is declined, so a new session has to be started.

10. The method of claim 8, wherein if the medical device declines a request to resume a session, the key response message that the medical device sends to the remote device contains null-bits as session identifier, and wherein after sending of the key response message the medical device terminates communication.

11. The method of claim 10, wherein the remote device terminates communications after the medical device has declined the request to resume a session.

12. The method of claim 8, wherein the medical device reads the master key of the session to be resumed from a storage repository and sends a key response message to the remote device that contains the session identifier of the session to be resumed, if the medical device accepts a request to resume a session.

13. The method of claim 12, wherein the remote device reads the master key of the session to be resumed from storage repository if the medical device accepts the request to resume a session, with the master key to be used for both decryption and encryption of the application data to be communicated.

14. The method of claim 12, wherein after the derivation of the master key or if applicable after the user has confirmed that the verification data computed by the remote device and the medical device have the same values the pairing of the medical device and the remote device is completed and communication between the medical device and the remote device is terminated.

15. The method of claim 14, wherein after termination of the communication, the remote device sends a connection request to the medical device, the connection request containing a session identifier.

16. The method of claim 15, wherein the medical device discards the connection request, if the session identifier is invalid.

17. The method of claim 15, wherein the medical device sends an acknowledgement message to the remote device, if it accepts the connection request, and reads the master key of the session identified by the session identifier of the connection request from storage repository, and wherein the remote device after receipt of the acknowledgement message reads the master key from storage repository, so that cryptographic communication of the application data can commence.

18. A system for establishing cryptographic communications, the system comprising a remote device and a medical device which performs the method of claim 1.

19. A system of claim 18, wherein the medical device is an insulin pump.