A quite unique feature of wolfBoot is the possibility to update the firmware using signed incremental updates.
The mechanism relies on a delta algorithm that produces a small update package. Instead of transferring the entire binary image of the firmware update, incremental updates only contain the binary difference with the previous version.
Distributing a new version of the firmware, even if it contains only a few modifications to the existing code, currently requires to transfer, verify and install the complete firmware image. Using incremental updates instead will result in a very small package, only containing the binary difference from the current firmware version. The package will still be signed, authenticated and checked for integrity using wolfBoot built-in image verification. WolfBoot will apply the binary difference in place on the BOOT partition in the FLASH memory.
There are multiple advantages of opting for such a mechanism: the firmware image, normally very large, must be transferred to the target system. On small-bandwidth networks such as LP-WAN, typically the bit-rate is too low to consider full updates, while a delta-based, incremental mechanism would make it usable. Moreover, from the point of view of non-volatile memory usage, it will no longer be needed to reserve two partitions of the same size by dividing the usable FLASH memory. The update partition may become much smaller since it will only be used to store the delta, freeing up space to allow a larger firmware to run in the BOOT partition.
At wolfSSL we are constantly adding new features and expanding the possibilities to secure your embedded systems. Let us know what you think about incremental updates in wolfBoot, and give us feedback about what you would like to see next in our products, by contacting us at facts@wolfssl.com, or call us at +1 425 245 8247