shallot

I'm guessing they used something like scallion [0] or Shallot [1]. Bench marking Shallot on an Intel 3350P@3.10GHz: time ./shallot ^a -> 0.09 sec user time ./shallot ^aa -> 0.12 sec user time ./shallot ^aaa -> 0.12 sec user time ./shallot ^aaaa -> 0.47 sec user time ./shallot ^aaaaa -> 5.92 sec user time ./shallot ^aaaaaa -> 118 sec user Unfortunately OpenCL doesn't work with the nouveau drivers so I can't test scallion. Who knows how much they spent trying to brute force that onion address. EDIT: Ok looks like they went the backronym route [0] https://github.com/lachesis/scallion [1] https://github.com/katmagic/Shallot

There are a few different programs that will do it, but it comes down to brute force, so the difficulty depends on the length. https://github.com/katmagic/Shallot https://github.com/lachesis/scallion