sorting with expensive compares?

[Thomas Wouters]

On Fri, 23 Dec 2005 21:56:44 -0800, Paul Rubin wrote:

> Steven D'Aprano <steve at REMOVETHIScyber.com.au> writes:
>> > There are also known ways of deliberately constructing md5 collisions
>> > (i.e. md5 is broken).  Whether the OP should care about that depends
>> > on the application.
>> 
>> Sure, but I don't he is deliberately trying to sabotage his own files :-)
> 
> He might have downloaded a file created by a saboteur to have the same
> md5 as some popular music file, but which contains a subliminal
> hypnotic message which will brainwash him if played.  Using a stronger
> hash, such as sha256, should protect him from this fate.

But the odds of such a message having the same MD5 as an existing
song on his disk is quite a lot higher than 2**64, unless he has a really,
really large music collection ;) In the case you propose, two files don't
just need to have the same MD5, but they also need to have a whole lot of
other characterstics; both need to be (somewhat) valid MP3's, one needs to
be a piece of music (or other sound) that is somewhat to the target's
liking, and the other needs to be something playable with a subliminal
message the target is likely to respond to.

Calculate-me-odds-on-THAT-<wink>-ly 'yrs,
-- 
Thomas Wouters <thomas at xs4all.net>

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