Date: Sun, 21 Aug 2011 18:37:17 +0400 From: Solar Designer <solar@...nwall.com> To: john-users@...ts.openwall.com Subject: Re: Some problems to build chr On Sun, Aug 21, 2011 at 03:41:37PM +0200, madfran wrote: > If I understood well, to avoid a overflow: > ((SIZE ** LENGTH) * SCALE) must fit in 64 bits. > That means ((SIZE ** LENGTH) * SCALE) < 2**64 > So, if I want to cover the complete range of characters (FF) the max. > > size must be 8 and the scale 1. > 256**8*1 = 2**64 That's almost correct. You can't really have 256 characters, because NUL terminates a string in C (and thus not only in JtR, but also in many/most systems that the passwords being cracked could be used on). So the maximum is 255 different ASCII codes, 1 through 0xFF inclusive. Also, the actual requirement is slightly more relaxed than what the comment says, so some higher values of SCALE will also work with 255 characters and length 8 - e.g., I've just tested that SCALE of 10 also works, resulting in slightly greater precision and thus maybe more optimal order in which candidate passwords are tried. You may give this a try if you like, or you may strictly meet the requirement stated in the comment, which means that SCALE must be 1 when SIZE is 255 and LENGTH is 8. Anyway, all of this complexity should be gone soon. Stay tuned. Alexander
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.