Secure boot is a security process that establishes a root of trust. It ensures that each component loaded during the boot sequence, from the initial bootloader to the operating system kernel, is cryptographically signed and verified. If the digital signature of any component is invalid or untrusted, the boot process is halted. This mechanism directly prevents the IoT gateway from loading and executing unauthorized or malicious firmware images, thereby achieving the engineer's goal of only loading verified software.

A. Implement Over-The-Air (OTA) updates: This is a method for delivering firmware updates, not a mechanism for verifying the integrity of the image during the device's boot process.

C. Enforce a measured boot function: Measured boot records cryptographic hashes of boot components into a Trusted Platform Module (TPM) for later attestation but does not inherently prevent an unverified image from loading.

D. Harden the update server: This is a crucial server-side security measure but does not protect the gateway itself from loading a malicious image obtained through other channels (e.g., physical access).

1. Sadeghi

A.-R.

Wachsmann

C.

& Waidner

M. (2015). "Security and Privacy Challenges in Industrial Internet of Things." 52nd ACM/EDAC/IEEE Design Automation Conference (DAC). In Section III.A

"Trusted Platform

" the paper emphasizes that a secure boot process is fundamental to establishing a trusted computing base on an IoT device by verifying the authenticity and integrity of firmware. DOI: 10.1145/2744769.2747942.

2. NXP Semiconductors. (2021). AN4581: HABv4 Secure Boot on i.MX 6/7 Series. In Section 2

"High Assurance Boot (HAB) Introduction

" p. 5

it is stated that "HAB allows customers to sign their boot images... On every boot

the i.MX processor authenticates the image signature. If the authentication fails

the boot is terminated." This directly describes the function of secure boot.

3. Stancill

B. (2021). Building a Secure Boot Chain for an IoT Device. Courseware

University of Colorado Boulder. In the "Secure Boot" section

the material explains that the process creates a "chain of trust" where each stage verifies the next

ensuring "that the device is running authentic software."