On Thu, Oct 27, 2005 at 09:59:56AM -0400, [EMAIL PROTECTED] wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > - Open and dark freenet, and open I2P, are vulnerable to intersection > > attacks, once the network is known. > > Right.
Sorry, I didn't mean intersection attacks, I meant traffic analysis
along the lines of one-packet-in-one-packet-out. But yes, of course
there are intersection attacks too. The point about intersection attacks
is that they are as much about getting people to keep their nodes up
24x7, and sensible patterns of usage (e.g. using a distributed store for
what you can use it for), as they are about passive traffic analysis.
>
> > - Both dark and open (maybe) freenet can be insulated from this via CBR
> > links because nodes are of low order and links change slowly. - IF there
> > is no fundamental problem with CBR links. I2P probably can't be.
>
> I'd posit that "IF" is appropriately questionable ;)
I'm not sure why. There is a big problem with CBR *tunnels*. What is the
big problem with CBR *links* ?
>
> Also see the other responses regarding the necessity and
> appropriateness of CBR for I2P tunnel creation messages.
Right, there is a problem for tunnels. What about links?
>
> > - Open I2P is vulnerable to connection setup attacks. Freenet isn't, if
> > it tunnels 1:1 tunnels inside its existing links. This will obviously
> > be slower than I2P's fixed length open tunnels, so cannot have the
> > same use cases.
>
> Ah, I see! You're mixing tunnels with connections again. I2P is
> entirely message based - it has only one transport layer connection
> to a peer, and all tunnel (and non-tunnel) traffic is multiplexed
> over it.
I am? Lets set some terminology:
Links - We have a maximum of one connection at the link layer between any
two nodes.
Tunnels - These are within the network, used for client applications.
Tunnel CBR - Tunnels send one packet of fixed size every X millis, at
each endpoint. These can be delayed or dropped by intermediaries.
Hostile nodes which observe these and are on the request chain can do
this maliciously, or can observe it to correlate the tunnel. Passive
analysts may also be able to use this to identify the tunnel's path.
Link CBR - Between two nodes, we send a fixed rate of fixed size
packets.
What I am proposing is that a system based on expander graphs, or on
human-originated connections (i.e. darknet), can do *link level* CBR.
This then eliminates practically all threat from external global traffic
analysis, provided that it can provide all required services without
having to set up additional connections. This is as opposed to a system
such as I2P operates now, where connections are set up on the whim of
the tunnel creator, where passive traffic analysis can probably reveal
where the tunnel is going to, unless either its construction is so slow
that it's impossible to tell it from the other tunnels (this is a
serious option; users may not mind it if we give them a nice GUI), or we
are very lucky with cover traffic.
>
> So, no, I disagree with your assessment.
>
> > - Open freenet and open I2P are harvestable.
>
> Aye, and both hybrid freenet and restricted routes I2P offer the
> same harvesting protections (as long as the fragments at the edges
> are small)
Both are not harvestable as such. It may be possible to find the nodes
via traffic analysis, but I don't define that as harvesting. :)
>
> > - To identify nodes on darknet freenet or I2P requires that a) Nodes be
> > probabilistically identifiable by their local traffic patterns (which
> > is likely, at least for the time being), and b) The attacker has the
> > ability to surveil a smallish number of chosen individual IPs in
> > detail at once, in order to pull off this attack.
>
> Agreed. (a) is cheap, while (b) is more expensive.
a) is a property of currently available real time stego. b) is a
property of the attacker. Both are required.
>
> > - If open Freenet uses open I2P as a basis, it *loses* anonymity (and
> > gains speed) relative to implementing its own mixnet and 1:1 streams.
> > A powerful passive attacker who permits the running of nodes can break
> > the mixnet. It is possible to use both internal and external streams,
> > for different use cases, however we would lose the ability to do CBR
> > at link level.
>
> I'm not sure this conclusion follows. Given the subsequent posts, do
> you still think it holds?
>
> > - If dark Freenet uses dark I2P as a basis, it loses nothing, provided
> > that dark I2P provides the ability to do link level CBR.
>
> That we can, but CBR is a bright neon light when you view it in
> terms of a darknet. 10 different CBR transmissions going 24x7 is
> pretty easy to spot.
True enough, but it's pretty easy to spot anyway, and CBR can be
regarded as a proxy for "link rate determined by transport".
>
> > - An attacker powerful enough to pull off the attacks mentioned could
> > probably identify nodes on an internet-hosted darknet, unless there is
> > some breakthrough in steganography e.g. parasitic traffic.
> > Nonetheless, open freenet would be less secure over I2P than
> > implementing its own internal mechanisms (which could be the same as
> > used on the darknet), and dark freenet would gain little from I2P.
>
> Agreed with the former ("could probably identify nodes"), but the
> later parts don't seem to follow.
>
> =jr
--
Matthew J Toseland - [EMAIL PROTECTED]
Freenet Project Official Codemonkey - http://freenetproject.org/
ICTHUS - Nothing is impossible. Our Boss says so.
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