Comment by thesh4d0w
4 hours ago
I use them in an esp32 to write a random password to each of my products, so when I sell them they can each have their own secure default wifi password while all using the same firmware.
4 hours ago
I use them in an esp32 to write a random password to each of my products, so when I sell them they can each have their own secure default wifi password while all using the same firmware.
What advantage do you see from using eFuses and not some other way to store the password?
This is the only way I could come up with that would allow an end user to do a full factory reset, and end up back in a known good secure state afterwards.
Storing it in the firmware would mean every user has the same key. Storing it in eeprom means a factory reset will clear it. This allows me to ship hardware with the default key on a sticker on the side, and let's a non technical user reset it back to that if they need to.
It gives you a 256bit block to work with - https://docs.espressif.com/projects/esp-idf/en/stable/esp32/...
But couldn't you also just set aside a bit of the EEPROM your factory reset skips, and accomplish the same thing?