Is it possible to "hash" a circuit board?
It is not possible to do a unique hash like you suggest, however there are test methods to verify a PCB functions as it is supposed to be, this is to ensure components are all there and aren't swapped around during manufacture. Normally used to factory test a board.
It is possible to get signatures from a digital board, we used to do that in the 80's mainly for primitive computers back then, you would pull the CPU , plug it into a &quot;NOP&quot; fixture, and the CPU would cycle through all 65536 addresses, then you would take a probe, and it would show a different 4digit number when you poked in different places , if the signature was wrong you were close to the fault. This wasn't as useful as originally thought and has fallen out of favour.
What we do now is use JTAG , and you would generally plug the board into some sort of fixture. JTAG allows you to chain many digital IC's together with only 4wires, and you can program any device, verify it , or read and write to any physical pin. See https://en.wikipedia.org/wiki/JTAG , but there is no &quot;Unique hash&quot; , but there will be a unique signature for each test file that is run, about as close as we can get.