[ESP8266] use soft signing

[Anduril]

Hey there,

I tried to use soft signing with my ESP8266 gateway and a nano node.
I have both setup with the SecurityPersonalizer to the same Soft-HMAC. But what pin to use as soft signing seed?

[scalz]

Hello @Anduril

From the doc here https://www.mysensors.org/about/signing

"For the software backed signingbackend, an unconnected analog pin is required to set a random seed for the pseudo-random generator. It is important that the pin is floating, or the output of the pseudo-random generator will be predictable, and thus compromise the signatures. "

So for instance, adcs like A6, A7 etc. let it floating (not connected).

[Anduril]

yeah I know the reason for having an unconnected analog pin, my question was more about which to use on an ESP. Does it have an A7? I don't find one in the pinout. I only see A0 (which is not used in my case), can this be the floating pin for soft signing?

[scalz]

ah oki, lol how i didn't see that
yep on esp8266 you have only one adc, so it's A0

[Anduril]

ok so

// Select soft/hardware signing method
#define MY_SIGNING_SOFT //!< Software signing
//#define MY_SIGNING_ATSHA204 //!< Hardware signing using ATSHA204A

// SETTINGS FOR MY_SIGNING_SOFT
#define MY_SIGNING_SOFT_RANDOMSEED_PIN A0 //!< Unconnected analog pin for random seed

should give a good random signing.