Can you use BLK3 to store an arbitrary unique id?

cmorgan
Posts: 53
Joined: Thu Aug 24, 2017 12:52 am

Can you use BLK3 to store an arbitrary unique id?

Postby cmorgan » Fri Nov 24, 2017 8:39 pm

I had posted a while ago about a unique id on the ESP32 for use in authenticating commands.

Using espefuse.py I burnt a key to BLK3 like:

$IDF_PATH/components/esptool_py/esptool/espefuse.py --port /dev/ttyUSB0 burn_key BLK3 blk3_key.bin

Note that I used 'burn_key' because it seemed like the best approach but now the key isn't readable, even by the micro:

BLK1 Flash encryption key
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLK2 Secure boot key
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLK3 Variable Block 3
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -/-

Should I have used 'burn_efuse' instead to avoid READ and WRITE from being cleared?

I'm asking because I only have so many esp-wroom-32 modules here and I'd prefer not to lock myself out of a second one :-)

cmorgan
Posts: 53
Joined: Thu Aug 24, 2017 12:52 am

Re: Can you use BLK3 to store an arbitrary unique id?

Postby cmorgan » Fri Nov 24, 2017 9:29 pm

Apparently I should have added '--no-protect-key' at the end of the command! Would be great if that option was documented in the espefuse.py help but I should have read the wiki page more carefully in any case.

I'm going to swap the module out for another one and see how that option works.

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