[Grapevine-devel] Re: Grapevine commentary

[Stephen B. <st...@bl...>]

=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Fri, 31 Oct 2003 15:29, you wrote:
> > The whole SAHP/Hash cash thing needs finishing (not important right
> > now).
>
> Please correct me if I have the wrong ideas here...
>
> The virtual network structure in a network under Grapevine requires a
> rigid shape.

Rigid, but able to change easily when nodes appear and disappear.

> Joining nodes are not assigned a place... why not?

Because I couldn't think of a satisfactory way of doing it.  The grapevine.=
pdf=20
document describes an alternative approach, and SAHP seemed preferable.

> Joining nodes want to pick out a place so they can do stuff, but they
> can't be allowed to pick the location they want in case they're bad
> nodes and they surround and strangle a legitimate node.

Correct.

> So you use SAHP to require that joining nodes must do some brute force
> attacks before they're given the place that they've picked.

That's correct.

> Can you allow a shortcut for that?  Like, can the administrators of each
> node decide they want to connect no matter what anyone else says?

One possible short-cut (Anthony's idea) would be for someone to send an=20
"invitation" to a friend which contains an already-calculated location, as=
=20
well as a list of seed nodes.  That would allow a new person to join=20
immediately on the recommendation of a friend.  The disadvantage is that it=
=20
would also need to contain a private key (on account of the way SAHP works)=
=2E =20
Normally you don't let private keys travel around the network.

> Is it at all possible to make the node-joining method a policy decision
> for the end users?

I see what you mean - each node specifies its own policy for prospective ne=
w=20
nodes.  That might form part of a more sophisticated SAHP, but I wouldn't l=
et=20
the actual human being dictate it.  The network should "just work" from the=
=20
user's point of view.

> > Also, someone needs to sit down and work out how to turn the whole
> > thing into a mix-net (not important right now).
>
> Then I won't learn what a mix-net is... :-)

A mix-net is a network that makes its traffic patterns look random, in orde=
r=20
to protect against attacks by people who can monitor the traffic and do=20
sophisticated analysis on it.  Remember that the messages themselves are=20
encrypted, so the attacker can't learn anything from them - but we also nee=
d=20
to ensure the sizes of the messages don't give anything away.

> > Another problem is the issue of making files drop off the network all
> > in one go, instead of becoming gradually fragmented.
>
> Would it be possible to have file sponsors who keep the whole file
> (like Bittorrent seeds)?  If someone wants to keep the file on the
> network they have to commit to keeping a seed running.

That is technically possible and would be a far easier way to solve the=20
problem, but it would prevent anonymous publishing, which is one of the mos=
t=20
important goals of this system.


Steve
=2D----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)

iD8DBQE/odmqODO5z8eA7sQRAgNzAKCf9z8TvX+IcDO5/+5FDbRa5LWpwACbBzV4
5/A8aG4BpEgzlqFtDsszwp4=3D
=3DiEKQ
=2D----END PGP SIGNATURE-----