Date: Thu, 7 Feb 2013 08:02:07 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: NetNTLMv1 and MSCHAPv2 magnum - On Thu, Feb 07, 2013 at 07:56:01AM +0400, Solar Designer wrote: > As to speeding up NetNTLMv1 and MSCHAPv2 some more, if we care, we may > want to split the crypt_key array in two, one for 2-byte "hot" > portions of the output and the other for 14-byte "cold" portions (may > expand them to 16 bytes for faster index to offset calculation). > Allocating 21 or 22 bytes wastes cache space. We only use 21 in > cmp_exact(), for one hash at a time - we could use a local variable > there instead. I am not going to work on this now. You may. :-) Taking this a step further, we could store just a few bytes of the 14-byte portion, and recompute the rest of the NT hash in cmp_exact() when we have to. ... and if we store e.g. just last 4 bytes of each NT hash, then we can get away with using just one array, like we do now. 2 bytes of each element will be directly compared to the known values for the 3rd DES block key, and 2 bytes before those last 2 will be compared to results of DES encryption of the 2nd block, which are computed as needed. I think I like this option best. Separating the hot/cold arrays has some cost of its own, and we can avoid that by simply making each element this small (only 4 bytes). The index to offset calculation becomes trivial (and supported in x86's addressing modes natively). Alexander
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