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To add to J.R.’s last paragraph: in the past few decades, crack (as a verb) has acquired the meaning of “commit computer crime”.  Most people consider crack to be synonymous with hack in this context; some people in the computer security field prefer to use hack to refer to solving difficult computer problems (such as penetrating security systems), without the connotation of malice.  See Is the term “hack” more positive or more negative? on EL&U.