Wireless Programmer Authentication for Implantable Medical Devices
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Solution Overview
Problem
Medical systems, such as implantable medical devices, are vulnerable to unauthorized programming due to the susceptibility of shared link keys being acquired by unauthorized users, leading to potential modifications of the operating configuration.
Innovation Solution
Implementing a multi-level authentication process involving a wireless communications module and control circuitry that verifies the authenticity of an external programmer by comparing encrypted and unencrypted versions of a random number, and a manually triggered wireless actuator to ensure secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Bluetooth link key authentication is used for wireless communication between external programmer and medical device, then ease of operation is improved, but security is worsened due to vulnerability of shared link keys
Solution Approach 1:
The authentication process is divided into two distinct levels: first, Bluetooth link key authentication for establishing wireless communication, and second, a proprietary challenge-response authentication using encrypted random numbers for verifying programmer identity. This segmentation allows each authentication method to perform its specialized function while together they provide both ease of operation and security.
Solution Approach 2:
A proprietary authentication protocol acts as an intermediary layer between the Bluetooth connection and the programming operations. This intermediary uses encrypted random number challenges and responses to verify the external programmer's identity without interfering with the underlying Bluetooth communication mechanism.
2Device complexity
If shared link key is used for authentication, then device complexity is reduced, but security is worsened due to susceptibility to hijacking
Solution Approach 1:
The authentication system is segmented into two layers: the simpler Bluetooth link key layer for basic connection establishment, and the more secure proprietary challenge-response layer for identity verification. This allows the system to maintain low complexity for wireless setup while adding security without significantly increasing overall system complexity.
Solution Approach 2:
The Bluetooth pairing and link key establishment is performed as a preliminary action before the secure programming session begins. This preliminary authentication simplifies the subsequent secure communication by having the complex cryptographic setup completed in advance, while the proprietary authentication provides the necessary security guarantee.
3Reliability
If multi-level authentication procedure is implemented, then security is improved, but device complexity is worsened
Solution Approach 1:
The proprietary authentication protocol serves as an intermediary that bridges the simple Bluetooth connection and the secure programming operations. It adds necessary security verification through encrypted challenge-response mechanisms without requiring fundamental changes to the underlying Bluetooth infrastructure or the programming device architecture.
Solution Approach 2:
The authentication mechanism uses cryptographic copying where the external programmer generates and transmits an encrypted copy of a random number in response to a challenge. This cryptographic copy verification provides security without requiring physical duplication or complex hardware modifications, relying instead on software-based cryptographic operations.
Data Source
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AI summary
A medical device of a medical system is configured for communicating with an external programmer over a wireless communications link. The medical device comprises a wireless communications module configured for receiving a first unencrypted version of a random number and a first encrypted version of the random number from the external programmer over the wireless communications link. The medical device further comprises control circuitry configured for performing an authentication procedure on the external programmer based on the first unencrypted version of the random number and the first encrypted version of the random number, and preventing the external programmer from commanding the medical device to perform an action unless the authentication procedure is successful.