What are the best practices for BLE security and privacy?

1 Understand the BLE stack

The BLE stack consists of four layers: the physical layer, the link layer, the host layer, and the application layer. Each layer has its own role and features, but also its own risks and limitations. For example, the physical layer handles the radio frequency modulation and demodulation, but it is susceptible to jamming and interference. The link layer manages the connection and encryption between devices, but it relies on a weak pairing mechanism and a fixed key. The host layer provides the core protocols and profiles for data exchange, but it exposes sensitive information such as device name and services. The application layer defines the custom data formats and functions, but it may contain bugs or vulnerabilities. Therefore, you need to understand how each layer works, and how to secure and optimize it for your specific use case.

2 Use encryption and authentication

Encryption and authentication are essential for protecting the confidentiality, integrity, and authenticity of data transmitted over BLE. Encryption prevents unauthorized parties from reading or modifying the data, while authentication verifies the identity of the devices involved. There are different types of encryption and authentication methods available for BLE, depending on the layer and the scenario. For example, you can use AES-CCM encryption and ECDH key agreement at the link layer, or you can use TLS or DTLS encryption and certificates at the application layer. You should choose the most suitable method for your application, and avoid using weak or outdated algorithms or keys.

3 Implement privacy features

Privacy features are designed to prevent tracking or profiling of BLE devices by hiding or changing their identifiers or attributes. For example, you can use random or resolvable private addresses instead of public or static addresses at the link layer, or you can use generic attribute (GATT) privacy flags or service changed indications at the host layer. You should also limit the exposure of device information such as name, services, characteristics, or descriptors, and use encryption or authentication to restrict access to them. Additionally, you should follow the best practices for data minimization and consent, and only collect and share the data that is necessary and relevant for your application.

4 Test and update your firmware

Testing and updating your firmware is crucial for ensuring the functionality and security of your BLE devices. You should perform regular tests and audits on your firmware, using various tools and techniques such as code analysis, fuzzing, penetration testing, or vulnerability scanning. You should also monitor and address any bugs, issues, or feedback that arise from your users or the community. Moreover, you should provide timely and secure updates for your firmware, using methods such as over-the-air (OTA) updates or secure bootloaders. You should also inform your users about the updates and their benefits, and encourage them to install them as soon as possible.

5 Follow the standards and guidelines

Following the standards and guidelines for BLE security and privacy can help you comply with the best practices and avoid common pitfalls. There are several sources of standards and guidelines that you can consult, such as the Bluetooth Special Interest Group (SIG), the National Institute of Standards and Technology (NIST), the Internet Engineering Task Force (IETF), or the Open Web Application Security Project (OWASP). These sources provide recommendations and specifications for various aspects of BLE security and privacy, such as encryption, authentication, privacy, testing, updating, or risk assessment. You should review and adhere to these standards and guidelines, and keep yourself updated with the latest developments and changes.

6 Educate your users

Educating your users is an important part of BLE security and privacy, as they are the ones who ultimately use and control your devices. You should provide clear and accessible information and instructions to your users, such as how to pair, connect, disconnect, or unpair their devices, how to enable or disable certain features or settings, how to check or update their firmware, or how to report or resolve any problems or incidents. You should also raise awareness and educate your users about the potential risks and threats of BLE, and how to protect themselves and their data. For example, you can advise your users to use strong passwords or PINs, to avoid connecting to unknown or untrusted devices, to turn off their Bluetooth when not in use, or to use a VPN or firewall when accessing the internet via BLE.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?