Date: Fri, 18 May 2012 13:31:35 -0500 From: "jfoug" <jfoug@....net> To: <john-users@...ts.openwall.com> Subject: RE: Performance Considerations of stdin >From: Brad Tilley [mailto:brad@...ystems.com] > >What, if any, performance considerations are there when passing word >candidates to JTR via stdin? I plan on doing some tests to see first- >hand, but before doing so I wanted to ask here in case others have had >some experience with this. > >Basically, I'm wondering if a word generation program that passed words >into JTR via stdin would perform better than when JTR is doing both word >mangling and hash generation, hash testing, etc all by itself. > >ehco -n word | john --sdtin > >Has anyone had experience performance testing something such as this? Depends upon the OS. If it is winblows, then the performance is horrible. I get about 30% or so performance for fast hashes, vs a dictionary read into memory, with rules run on the dictionary. Windows has a TINY pipe_buffer. I have found no way to speed this up (and I have tried). However, for many other OS's, may likely be a performance boost by using -stdin mode, IF doing some complex work, since you can do much more complex things a lot more efficiently in a native language (like C, or even perl), much faster than john's rules. I have done this for things like a super elite builder, which can do all sorts of permutations, such as full permutation of letter case, case, full permutation of all elite possibilities (such as mississippi -> m1ssissippi, miss1ssippi, m1ss1ssippi, ... m!ssiss1pp|, etc). Doing this in john, with rules, or other extern stuff 'could' be done, but that is beyond my capabilities, and I think you would either have to write a lot of rules that either reject a lot of input words, looking for specific patterns, or the rules would generate a lot of dupes. I also did this, for a much more heavily complex time/date generator, that did an all in one type run, and could handle much more than the external date_time code in john.conf. I would love to hear any speed comparisons between john -rules:xxx -memory=9999999 -w=input.dat candidates.in and word_gen input.dat | john --stdin candidates.in where the --rules:xxx (or externs, etc) and word_gen were 'comparable', when run on other OS's. Jim.
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