Re: Kernel SCM saga..

Bill Davidsen
2005-04-10T16:59:09Z

On Sun, 10 Apr 2005, Junio C Hamano wrote:

> >>>>> "DL" == David Lang <dlang@digitalinsight.com> writes:
>
> DL> just wanted to point out that recent news shows that sha1 isn't as
> DL> good as it was thought to be (far easier to deliberatly create
> DL> collisions then it should be)
>
> I suspect there is no need to do so...

It's possible to generate another object with the same hash, but:
- you can't just take your desired object and do magic to make it hash
right
- it may not have the same length (almost certainly)
- it's still non-trivial in terms of computation needed

>
> Message-ID: <Pine.LNX.4.58.0504090902170.1267@ppc970.osdl.org>
> From: Linus Torvalds <torvalds@osdl.org>
> Subject: Re: Kernel SCM saga..
> Date: Sat, 9 Apr 2005 09:16:22 -0700 (PDT)
>
> ...
>
> Linus
>
> (*) yeah, yeah, I know about the current theoretical case, and I don't
> care. Not only is it theoretical, the way my objects are packed you'd have
> to not just generate the same SHA1 for it, it would have to _also_ still
> be a valid zlib object _and_ get the header to match the "type + length"
> of object part. IOW, the object validity checks are actually even stricter
> than just "sha1 matches".
>
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--
bill davidsen <davidsen@tmr.com>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.