Proactive password checking with decision trees

The important problem of user password selection is addressed and a new proactive password checking technique is presented. In a training phase, a decision tree is generated based on a given dictionary of weak passwords. Then, the decision tree is used to determine whether a user password should be accepted. Experimental results described here show that the method leads to very high dictionary compression (from 100 to 3 in the average) with low error rates (of the order of 1%). We survey previous approaches to proactive password checking, and provide an in-depth comparison.