SHA1 collisions proven possisble

Sun Feb 26 23:15:58 UTC 2017

Patrick W. Gilmore wrote:
> I repeat something I've said a couple times in this thread: If I can
> somehow create two docs with the same hash, and somehow con someone
> into using one of them, chances are there are bigger problems than a
> SHA1 hash collision.

This collision turns a theoretical aspiration into a simple matter of
financials, and those financials will only reduce over time.

The incident needs to be taken in the context of how md5, rc4 and other
hash functions were relentlessly battered to death over time.  After the
first collisions are found in a hash function, exploits only improve, so
NIST's advice in 2004 to retire all SHA1 usage by 2010 was sound.

>From a practical point of view, the danger that this presents is
hypothetical for most people right now.  It's just not worth spending
6000 years of CPU time in order to steal €1000 from someone's bank.  But
by the same token, there are plenty of people in the world who would be
happy to invest this sort of computing power if the target were valuable
enough.

Nick