Re: NIST's policy: sha-1 until 2010, after 2010 sha-2.

On Dec 29, 2007 3:27 PM, J.C. Pizarro [off-list ref] wrote:

Dear Linus Torvalds,

What do you think to do when your git has to change from SHA-1 to SHA-2
  because of the weaker collision-resistance of SHA-1 in the next years?

    (e.g. from an damn developer trying to commit a collisioned-SHA-1 file)

It's a non-issue. The closest-to-practical attack method on SHA-1 is a
collision-finding attack, not a second pre-image attack, which means
you can find two messages with the same hash. As far as I know,
there's no significant weakness known for finding a pre-image, which
would be the most practical way of weakening Git's "security" via
SHA-1 substitution.

Regardless, the use of SHA-1 in Git isn't primarily for security,
though it is a nice side-effect. The SHA-1 is there for reliability in
addressing and as a good hash.


Dave.