binary file compare...

Steven D'Aprano steve at
Sat Apr 18 05:47:20 CEST 2009

On Fri, 17 Apr 2009 11:19:31 -0700, Adam Olsen wrote:

> Actually, *cryptographic* hashes handle that just fine.  Even for files
> with just a 1 bit change the output is totally different.  This is known
> as the Avalanche Effect.  Otherwise they'd be vulnerable to attacks.
> Which isn't to say you couldn't *construct* a pattern that it would be
> vulnerable to.  Figuring that out is pretty much the whole point of
> attacking a cryptographic hash.  MD5 has significant vulnerabilities by
> now, and other will in the future.  That's just a risk you need to
> manage.

There are demonstrated methods for constructing MD5 collisions against an 
arbitrary file in about a minute on a laptop computer.


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