This app is based on the GNUCitizen implementation of a algo calculating a WEP key based on Thomson based default ESSID. This will not sniff a WEP key from WIFI packets. Its mostly useless for the USA as most WIFI DSL providers offer TI modems usually. This app will work in Puerto Rico and most places in Wetern Europe. Also called STKeys in its base form.
Android also has these apps , Penetrate and Router KeyGen, although these were pulled out recenlty from the Market.

It seems to freeze , I guess the algo is not streamlined and these calculation , although its not math intensive, it hogs a lot a memory for variable matching.

Penetrate and Router KeyGen are much fasterm because they are based on a fixed database downloaded with the app. penetrate has a 45Mb db file and Router Keygen has a 28 Mb db file.
As Router Keygen is in the Google Code area, Diego should consider using the 28Mb db file to help his app.

You can also reduce the year search span in this app to avoid freezing. Until now it works very well where I live in PR.