介紹密碼被crack的原因，很貴的論文

-This paper surveys various techniques that have

been used in public or privates tools in order to enhance

the password cracking process. After a brief overview of this

process, it addresses the issues of algorithmic and implementation

optimisations, the use of special purpose hardware and

the use of the Markov chains tool. Experimental results are

then shown, comparing several implementations.