Medical Device Bluetooth Links With Out-of-Band Key Exchange

Solution Overview

Problem

Existing methods for securing data communication between portable medical devices and data management devices, such as insulin pumps and smartphones, lack comprehensive security measures, particularly at the application level, and do not allow for flexible connections between different devices.

Innovation Solution

A method involving out-of-band transmission of a public key using near-field communication (NFC) or display-based methods, followed by a Diffie-Hellman key exchange over Bluetooth, establishing an encrypted end-to-end connection with dynamically generated or stored key pairs for enhanced security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a static key is stored in all devices for additional security at the application level, then security is improved, but the system lacks flexibility and requires the same key on all devices

Engineering Contradiction:

ImprovesecurityVSAvoiddevice compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Public keys are pre-generated and stored in each medical device before use. This preliminary action enables secure communication without requiring manual key distribution or configuration, allowing devices to connect to multiple data management devices while maintaining security through pre-established cryptographic credentials

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system transitions from static key storage to dynamic key exchange using public key infrastructure. Each device generates its own key pair dynamically, and public keys are exchanged during connection establishment. This dynamic approach allows flexible connections between different device pairs while maintaining strong security through individualized cryptographic credentials

Inventive Principle:

Principle #15Dynamics

2Reliability

If a one-time password is used to generate a Bluetooth connection key, then security is improved, but the medical device must always be used with the same control unit

Engineering Contradiction:

ImprovesecurityVSAvoiddevice pairing flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Public keys are pre-generated and stored in each medical device before use. This preliminary action enables secure communication without requiring manual key distribution or configuration, allowing devices to connect to multiple data management devices while maintaining security through pre-established cryptographic credentials

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system transitions from static key storage to dynamic key exchange using public key infrastructure. Each device generates its own key pair dynamically, and public keys are exchanged during connection establishment. This dynamic approach allows flexible connections between different device pairs while maintaining strong security through individualized cryptographic credentials

Inventive Principle:

Principle #15Dynamics

3Device complexity

If only Bluetooth encryption is used for data transmission, then device complexity is reduced, but security against all attack scenarios is insufficient

Engineering Contradiction:

Improveencryption implementationVSAvoidsecurity coverage

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The security implementation is segmented into multiple layers: Bluetooth transport layer encryption for channel security, and application layer encryption using exchanged public keys for data security. This segmentation allows each layer to address specific security requirements, providing comprehensive protection against both interceptors and application-level attacks

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Public keys serve as an intermediary mechanism between devices. Instead of relying solely on Bluetooth's built-in encryption, the system introduces public key exchange as an intermediate step that enables additional encryption at the application level. This intermediary approach enhances security without requiring complete redesign of the communication protocol

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3949310B1Secure communication link between medical devices of a data management device

Publication Date: 2025.09.10 MYLIFE DIABETES CARE AG

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AI summary

The invention relates to a method for establishing an end-to-end encrypted data communication link between a portable medical apparatus and a data-management device. The method comprises at least the following steps: out-of-band transmission of a public key from the medical apparatus to the data-management device, wherein the transmission does not take place via Bluetooth; setting up an encrypted Bluetooth data communication link between the medical apparatus and the data-management device; transmitting a public key from the data-management device to the medical apparatus via the Bluetooth link that has been set up; calculating a combined key on the data-management device and on the medical apparatus; setting up an end-to-end encrypted link between the medical apparatus and the data-management device using the combined, preferably symmetrical, key.