Apologies to author of vanitygen, this is all conjecture on my part and I do not know if the previous unsolved theft had anything to do with vanitygen.
Author of the
Vanitygen is Jean-Luc.
WARNING: For a given secret prefix, the passwords this program generates
are always the same. Therefore, using a strong secret prefix is crucial.
Anyone who can guess your secret prefix can use this program to also
discover your password. You have been warned.
Unless you have a clue what the secret prefix of a particular account would be, it is extremely unlikely to find the password of a specific account.