4 ms·

So the "fast attack" uses the GPUs to compute on-demand, not using precomputed values?

• bigiain 11y ago
  Yep - plus a specialised password dictionary and bunch of heuristics to permute or mutate that dictionary. OCLHashcat can top a billion hashes a second for poorly chosen password hash algorithms - attackers just keep lists of every password exposure they coma across (starting with the 32 million passwords RockYou exposed to the world) - then combine that and a regular "common word/name/petname" dictionary, and try adding leading or trailing numbers, swapping numbers for letters l337-5p3ak style. One PC with some fairly recent video cards in it could blast through every dictionary word, a few thousand common names - and mutate all of those with common capitalisation and punctuation (you _did_ capitalise the first letter and add a fullstop or exclamation point at the end when the site forced you to use upper/lower and "special characters" right?), then they can add every combo of up to 4 training digits, anything that looks like a date, and they'll probably try using the domain name or bits of it if they know where the list came from (is your email password fluffycat-gmail or GoKitehawks2015-hotmail ?). If you're unlucky enough to be in a password list disclosure from a site still using MD5 (salted or not) that's literally a few _seconds_ work. Salted SHA might up that to minutes per password. Unless the site used bcrypt/scrypt/pbkdf2, if your password was in any way "predictable", someone with a box with 4 modern video cards (or stolen AWS credentials) will have found all the "low hanging fruit" passwords in hours or days.