Date: Sun, 25 Mar 2012 19:06:16 +0530 From: Dhiru Kholia <dhiru.kholia@...il.com> To: john-dev@...ts.openwall.com Subject: Re: PDF format On Sun, Mar 25, 2012 at 6:47 PM, <jfoug@....net> wrote: > Dhiru, > > The logic in get_salt() and set_salt() should be reversed. > > In pkzip format, (which could be used as a reference on 'how' to do this), in the get_salt() I create a complex structure, taking a lot of time, and doing a lot of validation/loading, etc. I then simply return the address to this structure, using an allocated pointer (which points to the just created structure). Then within set_salt, the code is VERY simple, and quick. Here it is on whole. > Within pdf (and a few other formats), a lot of time is spent within the set_salt function, parsing, allocating, setting up a complex structure. This type of work should NOT be done within the runtime loop. If done in set_key(), then it is in the runtime loop, and each salt computation will be done for EACH salt for EACH password (block of pw's) attempted. This time spent in set_salt() will GREATLY slow down the format. Thanks Jim and Solar. I will soon fix this issues for the formats I have written. For some formats, there is no "salt structure" as such (there is a single set of variables which the set_salt function modifies). -- Cheers, Dhiru
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