[BitTorrent] bt2 protocol features

Marcel Popescu mdpopescu at yahoo.com
Tue Jun 8 06:46:33 EDT 2004


From: "Vitenka" <vitenka at ntlworld.com>

> > MD5 and SHA1 are especially designed to be collission resistant. As a
> > result, the change you find a collission (two different inputs with the
same
> > output) is almost 0.
>
> Ok, resistant yes, impossible no.  A given hash size has only a finite
> number of possible hashes.
...
> However - under the new system it is not finding a piece of data for a
> given hash that is the problem.
> It is finding two pieces of data which happen to share a hash.  This is
> much much more likely.

Guys, please stop and think first. There are less than 32 million seconds in
a year - that's 3.2 x 10^6. If one would try 1000 hashes each second, it
would take thirty thousand billion (3 x 10^14) years before you could
generate the required 2^80 hashes (2^80 = 10^24; 10^24 / (3.2 x 10^6) / 10^3
= 3 x 10^14). Now, could we focus on something more realistic?

Mark




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