Date: Sun, 13 Nov 2005 18:32:43 +0300 From: Solar Designer <solar@...nwall.com> To: john-users@...ts.openwall.com Subject: Re: output tested hashes On Sun, Nov 13, 2005 at 09:47:14AM +0100, thomas springer wrote: > jup, precomputation, rainbowtables for the poor, if you like. > i'd like to have a few million "standard"-hashes with fixed salts, eg. > lm-hashes ready for lookup. [...] > i'm short on processor-time... It takes around 1 second to compute a few million LM hashes. It would take about the same amount of time to read them off a hard drive. OK, if your CPU is slow and your disks are fast, maybe you can get a 10x speedup, -- especially if you would be storing partial hashes only (like QCrack did). But why bother given that it's only a few seconds anyway? Even if you fill an entire hard drive with LM hashes and you're smart to only store partial hashes, you would save a few hours of CPU time at best. You can't save days of CPU time per hard drive in this way (on a reasonable system). You really should be using rainbow tables or not do any precomputation at all, -- unless your target hash type would be both slow and saltless (or allow for only a small number of different salts). -- Alexander Peslyak <solar at openwall.com> GPG key ID: B35D3598 fp: 6429 0D7E F130 C13E C929 6447 73C3 A290 B35D 3598 http://www.openwall.com - bringing security into open computing environments Was I helpful? Please give your feedback here: http://rate.affero.net/solar
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