4.2 Secure Firmware Update

The primary objective of secure firmware update is to ensure that only authenticated and unaltered firmware images are installed and executed. In dsPIC33A devices, the main hardware mechanism supporting secure firmware updates is the use of configurable Flash protection regions. These regions enable the segmentation of memory into distinct areas, such as the Immutable Root of Trust (IRT), download partitions and executable partitions. Each region can be individually configured to restrict read, write and execute permissions. By controlling these permissions for the corresponding memory region, we can reduce the risk of attacks through the firmware update interface. The firmware update process has two potential phases: the image download and the image installation. In some systems, these are not independent phases but part of one process.