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RE: [TSVN] Impact of GUID change?

From: Amir Kolsky <amir_at_xpandsoft.com>
Date: 2005-01-09 13:53:53 CET

MD-5 Hashes are not random, in the sense that they are generatable. However
they are what's mathematically known as one way functions - this means that
you can not determine the source of the hash by looking at the hash.

What's random is the distribution...

 Amir Kolsky
XP& Software

>-----Original Message-----
>From: SteveKing [mailto:steveking@gmx.ch]
>Sent: Friday, January 07, 2005 9:19 PM
>To: dev@tortoisesvn.tigris.org
>Subject: Re: [TSVN] Impact of GUID change?
>Will Dean wrote:
>> Well, I didn't believe you, because I had a quote of Larry Osterman
>> (sp?) saying that the new GUI algorithm was just an MD5 hash of the
>> old-style GUID.
>Never heard of that. But if you read about how hashes are
>built, you will discover that a hash has to be as random as
>possible (not in the sense that a hash of something will
>change, but if you change one byte of the source the result
>hash has to be as random as possible from the previous hash).
>Ok, not a very mathematical description, but I hope you get the point.
>> But not really believing anyone, I've just stepped through
>> and it does indeed just generate a pseudo-random number (I'm
>not sure
>> how it seeds this).
>> So I'll concede, your pseudo random numbers are probably
>just as good
>> as anyone else's!
>I've just read that in several places in the MS newsgroups
>that the GUIDs are created randomly. Not sure how exactly it
>is done though.
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Received on Sun Jan 9 13:43:35 2005

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