Re: Why SHA are 40 bytes? (aka looking for flames)

From: Marco Costalba <mcostalba@gmail.com>
Date: Apr 21, 2007, 16:58 UTC
Message-ID: <e5bfff550704210958j5506d533wa20834b9862457fd@mail.gmail.com>
In-Reply-To: <200704211608.06171.andyparkins@gmail.com>

On 4/21/07, Andy Parkins <andyparkins@gmail.com> wrote:

Show 10 quoted lines

> On Saturday 2007, April 21, Marco Costalba wrote:
> > Well, why to store always the full length SHA?
>
> Well apart from being easier than working out the optimum size for every
> single object write, one really good reason would be that there is no
> way to predict that an object in the future won't have a conflicting
> SHA - every object /has/ to be stored with its full hash, because you
> are preventing conflicts with everything object now, in the past and
> all possible futures.
>

Well, this is true also with 40 bytes sha, also if less probable.

Apart from this, when, in the future you are going to add an object that conflicts with an existing one you will handle that situation for the *new* object, as example storing with longer sha, without touching the existing one anymore.

Well I admit I don't know exacting what I'm saying, but sometimes ingenuity (a kind word to say ignorance) could lead to some surprises.

Marco