ESP32 Forum

Hi all.

I'm looking for either a private unique id or a good idea for where one should store such unique id. Looked at the mac address but imo that is visible if you sniff packets over the network so it wouldn't be private. I'd also like it to persist across a code load if possible.

Thoughts?

Chris

The MAC adresses could be used as the base of a larger UUID, by multiplying it with another fixed large number?
This would definitely make it less obvious as to where the UUID originates. However yes, this would be reasonably easy to figure out for someone who really wants to get into your system.

Another thing to mention is the esp32 is loaded with 4 unique MAC addresses. You only really need two (one for BLE and one for WiFi) in most cases. So you could use one of the other two?
The only downside to this is that the addresses will only differ from each other by a few bits.
Eg the wifi mac might be 21:22:23:24:25:26, and the hidden one used for an ID might be 21:22:23:24:25:27 or 21:22:23:24:25:28.

If this is not an acceptable form of an ID then generating your own and storing it in the efuse BLK3 address should be sufficeint. The efuse is OTP, so will persist across flashing/programming etc.
https://github.com/espressif/esptool/wi ... ning-a-key

Generate one and store in nvs or efuse. Or use flash chip id viewtopic.php?t=1481

Thank you for your replies. I'll try to make sure to let you know how I make out when I get back to doing so.