Re: Starting to think about sha-256?

[Jeff King <peff@peff.net>]

On Mon, Aug 28, 2006 at 10:56:01AM -0700, Linus Torvalds wrote:

> However, the "earlier will override" is very much what you want from a 
> security standpoint: remember that the git model is that you should 
> primarily trust only your _own_ repository. So if you do a "git pull", the 

This concept breaks down somewhat if you are pulling from two
repositories (one good and one evil). If I pull from the evil repo
first, that will become my "earlier" object, and I will never get the
colliding object from the good repo.

Executing such an attack might not be that hard, either (once we get
over that little hump of creating collisions at will!). The owner of
'evil' has to know a SHA1 that will be in 'good' before it makes it to
'good'. However, I imagine we frequently see SHA1s migrate from more
central repos (like .../torvalds/linux-2.6.git) to less central ones
(subsystem / port maintainers, etc).

-Peff