Synthesis of Secure Passwords

This paper studies a synthesis of password to be easily identified and hardly forgot. A new synthesis method is proposed to construct a good passwords that satisfy both requirements. Our method focuses on the change of frequency of combined words. Each of two words has a high term frequency but the combination is not quite common and then the frequency of the combined words can give strong impression in our memory. In order to verify our hypothesis, the paper presents a formal definitions of impression I, conflict C and accuracy A for synthesized words. The impression is a measure based on subjective evaluation for words. The conflict represents a degree how much reduction in frequency is given by combination of two words. The degree of conflict can be evaluated by a fraction of synthesized words in a particular corpus. The experimental results shows that the above hypothesis holds with positive correlation between accuracy for memory and the impression given from the synthesized words.