So next time someone stands next to me with a Radeon GPU I´ll turn it off
Seriously: can´t all password be hacked?
Yes they can ALL by hacked but some would take so long to gues that the sun would burn out first. I'd say if it takes over a million years you are safe. But 51 seconds is to short.
Why would some one want to sit a Starbucks and guess passwords, He may hope to collect some data from some one doing on-line shopping. Granted must people will not be typing in credits cards but if you wait long enough and if the process is automated you can just let it run for a few weeks.
This is the kind of "hack" some one might install in that 7/11 store that is next door to the Starbucks. He puts it in a closet and leavs it running for months. or maybe the machine sets in a car parked in the lot outside.
The four vide cards do NOT need to be physically at the Starbucks place, I could build a server at my house with a tiny Android phone left on a carter at serveral stores in the area. The phones send the passwords to my decrypt server.
Who would do this.. I had a credit card number stolen then he theft within a minuted had placed an order for $10,000 of wholesale women's clothing. I disputed the charge and did not pay it. (this CC number was stolen the old fashion way by a waiter in a restaurant. You give him your card and he buys something with in before he hands it back to you so it is not reported stolen.)
So there is good motivation to hack passwords. One in a hundreds times you can get maybe a CC number that is not reported stollen.
So to answer the question "Why woulf anyone pick me to target?" They don't they target everyone, thousands of people and you just happen to be in range.
What is the "range" of a WiFi? Using just a cell phone antenna not far. Using a big high gain antenna that is maybe about a foot long, 1/2 mile is not unreasonable. People have done 13 miles but that takes careful setup at each end.