Date: Wed, 23 Feb 2011 03:46:25 +0300 From: Solar Designer <solar@...nwall.com> To: john-users@...ts.openwall.com Subject: Re: MD5 Generic improvements Simon, On Mon, Feb 21, 2011 at 10:00:15AM +0100, Simon wrote: > On 18/02/2011 20:58, Solar Designer wrote: > > with this patch (maybe bugs). Simon - can you please take a look and > > likely upload a corrected patch against -jumbo-12? > > I checked this, and the problem is that there are two consecutive calls > to set_key() with the same index. I thought that the set_key() would > only be called with incremental indexes, except when it resets to 0. Are you referring to this added call? - /* Remove some old keys to better test cmp_all() */ if (index & 1) format->methods.set_key("", index); I think you're correct that it requires a property from "formats" that is not otherwise made use of by the rest of John. I might drop this along with reworking the self-tests such that multiple key slots are tested per crypt_all() call. For now, I think this is nice to have to test cmp_all() better when there are not enough different test vectors for all key slots being tested. > This format (and most of the things I wrote) works with this assumption, > and only cleans things up when set_key(x,0). Yeah, it turned out to be similar for JimF's, where the self-tests workaround was to change: index = (max > 5 && max > ntests) ? 5 : 0; to: index = (max > 5 && max > ntests && done != 1) ? 5 : 0; The former produced a sequence like: 0 1 2 3 4 6 9 ... 5 7 10 ... 5 7 10 ... The latter changed this to: 0 1 2 3 4 6 9 ... 5 7 10 ... 0 1 2 3 4 6 9 ... such that the zero index slot is hit before a slot is reused. > Having to work with arbitrary indexes would have a performance impact on > things like raw_md5. Is that the expected behavior of JtR ? I had assumed that set_key() would work on arbitrary indices, but I think this is not actually being relied upon anywhere in JtR, other than in these revised self-tests. So I was OK with relaxing the requirement as I documented above (this is already in jumbo-12). As to two consecutive set_key() calls for the same index, does supporting this still have any performance impact for any "format"? Thanks, Alexander
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