if I would like to exploit a used key by the side channel attack, where you measure electromagnetic fields, how many runs of the AES-128 do I need to spy for a successful exploit?
I can't use any programs or software on that device. AES is software implemented. And I try (theoretically!) to spy in a distance of X meters. I am able to reduce the noice by surrounding emissions. But I can't have any type of access. So the model of an attacker is a sniffer.
I do not need the exact amount, only some size, I could think of. I just found the TEMPEST attack, which needs 400k traces in a distance of 0.3 meters and 2.3m in 1 meter.