Unlocking the power of Azure IoT with private PKI x509 certificates

[Windows Server]

As the Internet of Things (IoT) landscape evolves, device identification is critical. In this guest blog post, Sukhyung Shin, Senior IoT Solutions Architect - Strategy, Keyfactor, discusses how Microsoft’s Azure IoT Hub (Azure IoT Hub) and IoT Hub Device Provisioning Service (DPS) can employ public key infrastructure (PKI) to ensure robust security for IoT devices and their communications.

What is PKI?

PKI uses a pair of keys — a public key and a private key — to identify devices and secure internet communication. The public key is contained inside a certificate, which proves trust in the device’s identity. This trust is proven through a hierarchy of trusted entities, with absolute trust at the root level. The root level of trust is pre-trusted by the application.

Each certificate has a digital signature attached to it. The root signs itself. The root also signs certificates for lower-level trusts, which signs certificates for a device. When a digital certificate is presented, the recipient can verify its validity by checking the chain of signatures back to the absolute trust at the root level.

Private trust allows a company to ensure only devices it manufactures or has manufactured are allowed into the trusted ecosystem. This way, a company gains secure identification for valid devices.

PKI in Azure IoT Hub

Device authentication

Azure IoT Hub and DPS can leverage PKI for device authentication. This method utilizes certificates that include a device’s public key and identity information. When a device connects to Azure IoT Hub or DPS, its certificate is verified to confirm the device’s legitimacy, ensuring trusted communication. This prevents rogue devices from sending bad data to Azure IoT Hub.

Secure communication

Following authentication, Azure IoT Hub secures data transmission with encryption, allowing only the device holding the corresponding private key to decrypt and access the data. This process protects the data from being intercepted or tampered with during transmission.

Certificate authorities

Certificate Authorities (CA) sign certificates. Using a CA simplifies device identity management. The CA verifies device identities before issuing certificates, enhancing overall security.

Depiction of IoT environment.

Benefits of PKI in Microsoft’s Azure IoT environment

• Enhanced security: PKI ensures only authenticated devices connect to Azure IoT Hub or DPS and that their communications are encrypted.
• Scalability: PKI facilitates the management of numerous IoT devices, allowing for remote and automated certificate issuance, renewal, and revocation.
• Interoperability: Standard PKI protocols enable Azure IoT Hub and DPS to interact securely with various devices, regardless of manufacturer.
• Audit and compliance: PKI improves device interaction auditing, which is crucial for compliance in many sectors.

Implementation considerations

• Certificate management: Properly managing certificates — issuing, renewing, and revoking — is essential for maintaining security.
• Security of private keys: Devices must protect their private keys, preferably in secure, hardware-based storage, to prevent unauthorized access.
• Rotation of private keys: Just like passwords, the private (and associated public) keys should be rotated on a schedule. 
• Monitoring and response: Continuous monitoring for security breaches and effective response strategies for compromised devices or certificates are vital.

Ready to get started?

PKI is integral to securing device identities and communications in Azure IoT Hub, providing a reliable framework for authenticating and encrypting device data. By implementing PKI, companies can enhance the security and scalability of their IoT solutions, ensuring data integrity and compliance across diverse IoT deployments. As IoT technologies advance, PKI will continue to be a fundamental component in the secure and efficient management of IoT ecosystems.

Available in Azure Marketplace, Keyfactor Command for IoT is a leading PKI and certificate management platform that automates initial device provisioning into Azure IoT Hub or using DPS. Additionally, Keyfactor coordinates automating certificate rotation and keeps the device identity (certificate) synchronized with Azure IoT Hub. Want to try it out first? Check out the 30-day free evaluation.

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