binary file compare...

[Steven D'Aprano]

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.

http://en.wikipedia.org/wiki/MD5



-- 
Steven