Re: Re: CRC

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От Bruce Guenter
Тема Re: Re: CRC
Дата
Msg-id 20001211115418.A3838@em.ca
обсуждение исходный текст
Ответ на Re: Re: CRC  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
On Sun, Dec 10, 2000 at 02:36:38PM -0500, Tom Lane wrote:
> > MD4 would be a better choice than MD5, despite that a theoretical attack
> > on MD4 has been described (albeit never executed).  We don't even care
> > about real attacks, never mind theoretical ones.  What matters is that
> > MD4 is entirely good enough, and faster to compute than MD5.
>
> > I find these results very encouraging.  BSD-licensed MD4 code is readily
> > available, e.g. from any of the BSDs themselves.
>
> MD4 would be worth looking at, especially if it has less
> startup/shutdown overhead than MD5.  I think a 64-bit true CRC might
> also be worth looking at, just for completeness.  But I don't know
> where to find code for one.

The startup/shutdown for MD4 is identical to that of MD5, however the
inner loop is much smaller (a total of 48 operations instead of 64, with
fewer constants).  The inner MD4 loop is about 1.5 times the speed of
MD5.
--
Bruce Guenter <bruceg@em.ca>                       http://em.ca/~bruceg/

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