Methods and Apparatus for Generating Chaff Passwords for Use in a Password-Hardening System

Static and dynamic embodiments are presented for generating chaff passwords for use in a password-hardening system. Chaff passwords are generated by obtaining a source set of passwords comprising at least one valid password for each of a plurality of users; and generating a chaff set of passwords for a given user, wherein the chaff set comprises at least one valid password for the given user and a plurality of chaff passwords for the given user, wherein the plurality of chaff passwords for the given user are obtained from the source set of passwords. Chaff passwords can also be generated by modifying portions of base passwords based on a distribution with which particular strings of digits and symbols appear in user passwords. Location oblivious chaff passwords are generated from a chaff set of passwords obtained from a chaff generation method by applying a random permutation over the elements of the obtained chaff set of passwords.