Re: Does this exist ?

[Matjaz Debelak <killerx () sess-on net>]

Yes, that is true, but if you read the original post, he wants to
minimize the data transferred not the data stored/processed.

I don't know if you want to transfer general traffic that way, but if
you are only trying to transfer some special data/protocol it might be
even possible to generate such a thing for all the plausible packages
(if you know roughly what data will be "encoded")...

LP Killer_X

Fionnbharr wrote:
> Ah 2^4000 is rather big, I suggest you plug something less into a
> calculator to see how big 2^ can get. If you're looking for 16ish
> million entries you want 2^24.
>
> What you're kinda describing would work as far as I understand what it
> is you're trying to say. Along the same sort of arguments we can turn
> this into a compression algorithm where we represent the whole entire
> universe as the letter 'A'. The unfortunate part of this compression
> algorithm is that when we want to uncompress it we go to our table,
> look up what 'A' represents, and then output it. So we would still
> have to store the universe in as a whole.
>
> In other words it's terribly infeasible to have a database of all the
> possible packet combinations up to 500 bytes.
>
> On 06/07/07, Dan Becker <list () bsdnixsolutions com> wrote:
>   
> > Quoting Andrew Farmer <andfarm () gmail com>:
> >
> >     
> > > On 05 Jul 07, at 06:20, Dan Becker wrote:
> > >       
> > > > I have an idea that won't leave me alone and this list seems to
> > > > have the most potential for knowing if the idea exists. My
> > > > apologies for a somewhat offtopic post.
> > > >
> > > > Would there be a way to create a  rainbow table of tcp packets to
> > > > be used to generate one packet for every 1000 or so normal packets
> > > > simply by matching hashes with databases on both ends ?
> > > >         
> > > No; for a 128-bit hash (for example) there are only 2^128 packets which
> > > can be uniquely represented. This is far below the 2^12144 1518-byte
> > > packets which are possible, so - by the pigeonhole principle, there
> > > will be collisions. Increasing the hash size won't help unless you make
> > > it at least as large as the packet, at which point you aren't gaining
> > > anything.
> > >
> > > Computing such a rainbow table is computationally impossible, anyway.
> > > The largest keyspace which I know of that's been brute-forced was
> > > somewhere around 64 bits, and that takes either dedicated hardware or a
> > > distributed-computing network. 128 bits is believed to be physically
> > > impossible, and even that is just barely enough to fit a TCP header
> > > into, without any data.
> > >
> > > If the data being transmitted over the link is reasonably redundant,
> > > then you might get lucky and be able to just hash the relevant packets
> > > ahead of time. However, you could probably do even better with a
> > > purpose-built compression scheme anyway.
> > >       
> > I thank you for the reply and must apologize for using the wrong
> > terminology. A rainbow table isn't really what I am thinking about.
> >
> > Think of DNA strands, we all have the potential to be any living thing
> > on the planet. (to my limited understanding of DNA)
> >
> > Now lets apply that to digital data. We all have the 0's and 1's to be
> > any potential data already in the computer. Let us go further and
> > create a database of a packet data field with 500bytes in the data
> > field or 2^4000 which would come to 16 million entries. Modern
> > databases can do extremely quick lookups with the properly configured
> > database having that many entries.
> >
> > So we generate a packet using the idpacket field of a database to
> > describe which packets should be assembled in which order then send
> > it. 1 packet to send 500.
> >
> > Then upside is everyone has the potential to create any data possible
> > already at their command and data transmissions will be increased
> > exponentially. The downside being intellectual property is not going
> > to be easy to enforce considering all you are doing is defining the
> > order packets are assembled.
> >
> > Am I missing something ? Would a hash function not be able to do this
> > ? Would a packet checksum be similar to the hash function I am
> > thinking about ?
> >
> > Again my apologies for offtopic postings.
> >
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