How Offline QR Authentication Enhances Medical Device Cybersecurity

As medical technology evolves, so do the cyber threats that target it. In this landscape, authentication methods must be both robust and adaptable, even in offline environments. One particularly innovative solution is the use of QR-based authentication powered by digital certificates. In this blog post, we’ll explore a real-world implementation of this strategy in a medical setting and why it’s a game-changer for medical device cybersecurity. 

Why Offline Authentication Matters in Medical Devices 

Not all medical environments have reliable Internet access. Whether due to compliance policies, technical limitations, or safety protocols, some devices must operate offline. Yet, they still require secure user authentication to prevent unauthorized access to sensitive operations, especially in high-risk systems. 

This case study highlights an offline QR-based authentication system that utilizes Public Key Infrastructure (PKI) and digital certificates to securely validate user identities, even in the absence of internet access. Let’s break down how it works and what makes it effective. 

Step-by-Step: How the Offline QR Authentication System Works 

1 – Provisioning: Preparing the Device

Before the high-risk systems can authenticate any user offline, it must first be provisioned with two critical elements: 

• The Certificate Authority (CA) certificate 

• The public key associated to the certificate. 

This step ensures the device can validate any incoming QR code based on the public-private key pair and the PKI model.

2 – QR Code Generation and Delivery

The Service Software, typically installed on a secure administrator workstation, generates a QR code that includes: 

• Unique User Identifier 

• Hashed PIN (using SHA-256 or similar) 

• User Role  

• Expiration Date 

• Digitally signed token, including User Data and user Role, signed with the private key of the authentication service. 

This signed token is embedded in the QR code, which is then sent via email along with the secret PIN using an SMTP server.

3 – QR Code Verification by the Device

Once the QR code is scanned: 

• The device checks the expiration date 

• The digital signature is verified using the stored public key 

• The device validates the user info integrity 

• Finally, the user is prompted to enter the PIN 

If the PIN matches the hash in the QR code, access is granted. 

✅ Key Benefit: Even if someone intercepts the QR code without the secret PIN, they cannot gain access. 

 

Revoking Access: Smart, Secure Options 

Managing revocations is a critical aspect of any authentication system. The solution described offers three scalable revocation models: 

🔴 1. Blacklist-Based Revocation 

Each offline device stores a local blacklist of revoked users. This list is checked during every authentication attempt. Updates are applied during provisioning or routine maintenance. 

🔴 2. Hardware-Based Revocation 

QR codes can be issued on physical cards that must be returned upon role termination; however, this option is less practical for transient roles, such as nursing staff. 

🔴 3. Time-Limited QR Codes 

QR codes are set with short-term expiration dates. Revoked users are excluded from future renewals, effectively cutting off access without requiring manual deletion. 

 

Certificate Strategies: Balancing Security and Scalability 

1 – Minimal Option: One Certificate for All Devices 

• Pros: Easy to manage 

• Cons: If compromised, all devices are vulnerable 

2 – Intermediate Option: One Certificate per Device 

• Pros: Device-level isolation and security 

• Cons: More complex certificate management 

3 – Maximal Option: One Certificate per User + per Device 

• Pros: Maximum granularity and revocation control 

• Cons: High administrative overhead 

This layered approach enables OEMs to select a model that best aligns with their risk appetite and regulatory obligations. 

 

Why This Matters for Regulatory Compliance 

Implementing a solution like this directly supports the best practices and regulatory expectations outlined in: 

• IEC 81001-5-1: For cybersecurity in health software and health IT systems 

• FDA Premarket Cybersecurity Guidance 

• MDR (EU) and ISO 14971: Emphasizing security as a component of safety 

Offline authentication systems that follow Secure Development Lifecycle (SDLC) principles also enhance documentation for Security Risk Assessments, Threat Models, and Post-market Evaluations, as outlined in cybersecurity checklists for medical devices. 

 

Key Takeaways for Medical Device Manufacturers 

🔐 Security Without Connectivity

The use of QR codes and digital certificates bridges the gap between usability and security in offline environments. 

⚙️ Adaptability for Different Risk Levels

From low-risk environments that use shared certificates to high-security systems requiring per-user validation, the system is highly flexible. 

📜 Compliant by Design

The design supports documentation aligned with IEC 62304, ISO 14971, and FDA submission expectations, reducing regulatory friction. 

 

Ready to Upgrade Your Authentication Strategy? 

Cybersecurity for medical devices is no longer optional; it’s essential. If your systems operate offline or in limited-connectivity environments, this type of authentication solution can protect against unauthorized access, support postmarket surveillance, and reinforce your device’s compliance posture. 

 

📩 Let’s Talk

Want to explore how QR-based authentication can secure your devices? Our experts can help assess your infrastructure, define certificate strategies, and implement a compliant, scalable solution.