> But these "classes" have no meaning. What do you mean? They work for my purpose, which is being able to tell "password" and "passwrod" apart. There will be f

> But these "classes" have no meaning. What do you mean? They work for my purpose, which is being able to tell "password" and "passwrod" apart. There will be false positives, of course, but an (educated) assumption is that they are not going to be frequent for lexically related inputs.