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Date: Tue, 12 May 2015 00:23:20 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: sunmd5 assumes a SIMD width of 4
Solar, Lei,
I just saw this in sunmd5:
/*
* 576 divides evenly by 4, 8, 12, 16 (para = 1, 2, 3, 4) Each of these
* will get an even number of para buckets, so hopefully we get the best
* average fill we possibly can get. 960 would also allow us to pick up
20 (para 5)
*
* NOTE, made 'smaller' fit. 240 would get all 4,8,12,16,20, but now it
is multiple
* defines. this allows self tests to run much faster, BUT the speed of
the format
* is still about the same.
*/
//#define MAX_KEYS_PER_CRYPT 576
//#define MAX_KEYS_PER_CRYPT 240
#if !defined(MD5_SSE_PARA) || MD5_SSE_PARA==1
#define MAX_KEYS_PER_CRYPT 48
#elif MD5_SSE_PARA==2
#define MAX_KEYS_PER_CRYPT 64
#elif MD5_SSE_PARA==3 || MD5_SSE_PARA==4
#define MAX_KEYS_PER_CRYPT 96
#elif MD5_SSE_PARA==5
#define MAX_KEYS_PER_CRYPT 100
#endif
Unfortunately Jim has just assumed a SIMD width of 4 (again, doh). The
above will fail for certain combinations of width and interlaving
factors. For example, AVX2 at para 5 is 8x4 so 100 is not a very good
number to use.
I'm not sure why we're not just using eg.
#define MAX_KEYS_PER_CRYPT (SIMD_COEF_32 * MD5_SSE_PARA)
Perhaps with some fixed multipler if we really want to (not sure why we
would but I haven't looked much at the code).
magnum
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