Proactive Password Checking
with Decision Trees

F. Bergadano, B. Crispo and G. Ruffo

Università of Torino, Italy


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.

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This paper has been published in the Poceedings of the 1997 ACM Conference on Computer and Communication Security, April 1-4, 1997, Zurich, Switzerlands.