[Bro] Hashing incomplete files

[Josh Liburdi]

Kevin was correct -- filling in the incomplete space with nulls produces
the same MD5 hash.

Johanna, in the case of an "incomplete" file, could multiple simultaneous
streams produce an inconsistent hash? Not sure I understand how multiple
streams might affect a file's completeness, but would happy to hear your
thoughts.

Josh

On Tue, Apr 25, 2017 at 10:49 AM, Johanna Amann <johanna at icir.org> wrote:

> On Tue, Apr 25, 2017 at 02:34:41PM +0000, McMahon, Kevin J wrote:
> > I’m guessing that Bro doesn’t pass a string of nulls to the hash
> > function when there’s an undelivered chunk.  But that’s what ends up in
> > the file (I don’t know if that’s a side effect or intentional – but it
> > is useful as all the other bits end up in the right place and you can
> > find the holes after the fact).  So I wouldn’t expect that the hash
> > would be the same.
>
> Just to add a bit to this - I think this behavior is intentional and used,
> e.g., when a file is downloaded from over multiple streams simultaneously.
>
> Johanna
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ICSI.Berkeley.EDU/pipermail/bro/attachments/20170425/1790e244/attachment.html