are hashes calculated from data

Hello All,

I was wondering if the hashes are calculated solely from the data or if there is a seed taken from outside.

I ask because I'm wondering the following.

Given two separate git repositories initialized from the same subversion repository, if the hashes are calculated from the data alone, then those two repositories could theoretically pull/push branches from each other while retaining the ability to commit back to the "origin" subversion repository.

If this is in fact the case, it would make it quite simple for me to convince the more ambitious developers on our team to use git locally, and grow team usage in a passive, viral way.

~ Ray