IoT Security

When to use

• Designing device identity infrastructure using X.509 certificates, secure elements, or TPMs
• Implementing a secure boot chain from hardware root of trust to application firmware
• Configuring TLS 1.3 or DTLS for MQTT, HTTPS, CoAP, or LwM2M device communication
• Signing firmware images for OTA distribution and verifying them on-device
• Segmenting IoT devices on dedicated VLANs and configuring egress firewall rules
• Building device attestation workflows to detect tampering at scale
• Managing CVEs and SBOM tracking across a constrained device fleet

Core principles

1. Private keys never leave hardware — secure element or TPM for key operations; flash-stored keys are not keys, they are secrets waiting to be extracted
2. Chain of trust starts in ROM — every link in the boot chain verifies the next; one unsigned hop breaks the whole model
3. mTLS everywhere on the wire — device authenticates server, server authenticates device; one-way TLS is half a handshake
4. Sign firmware with an offline HSM key — the signing key never touches a networked machine; downgrade attacks need anti-rollback counters in OTP fuses
5. Segment and minimize blast radius — IoT VLAN, gateway as single egress, no device-to-device unless explicitly required

Reference Files

• references/device-identity-and-secure-boot.md — X.509 per-device certs, hardware security components (SE, TPM, TrustZone), identity lifecycle, secure boot chain from ROM to application
• references/communication-and-firmware-security.md — TLS 1.3 config, embedded TLS libraries (mbedTLS, wolfSSL), DTLS for UDP, firmware signing with HSM, anti-rollback counters
• references/network-and-vulnerability-management.md — VLAN segmentation, device attestation workflow, SBOM tracking, CVE prioritization, compensating controls for unpatched devices