• Posted: 2006-02-07
  • Author: I2P devs
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Hi y'all, tuesday rolls around again

* Index
1) Net status
2) _PRE net progress
3) I2Phex 0.1.1.37
4) ???

* 1) Net status

There haven't been any substantial changes on the live net over the
last week, so the live net status hasn't changed much.  On the other
hand...

* 2) _PRE net progress

Last week I started committing backwards incompatible code for the
0.6.1.10 release onto a separate branch in CVS (i2p_0_6_1_10_PRE),
and a cadre of volunteers have helped test this out.  This new _PRE
network cannot talk to the live net, and doesn't have any meaningful
anonymity (since there are under 10 peers).  With the pen register
logs from those routers, a few substantial bugs in both the new and
old code have been tracked down and swatted, though further testing
and improvement continues.

One aspect of the new tunnel creation crypto is that the creator
must do the heavy asymmetric encryption for each hop up front, while
the old tunnel creation did the encryption only if the previous hop
agreed to participate in the tunnel.  This encryption could take
400-1000ms or more, depending both on the local CPU performance and
on the tunnel length (it does a full ElGamal encryption for each
hop).  One optimization currently in use on the _PRE net is the use
of a short exponent [1] - rather than using a 2048bit 'x' as the
ElGamal key, we use a 228bit 'x', which is the suggested length to
match the work of the discrete log problem.  This has dropped the
per-hop encryption time by an order of magnitude, though doesn't
affect the decryption time.

There are a lot of conflicting views of the use of short exponents,
and in the general case it is not safe, but from what I've been able
to gather, since we use a fixed safe prime (Oakley group 14 [2]),
the order of q should be fine.  If anyone has any further thoughts
in this vein, however, I'd love to hear more.

The one big alternative is to switch to 1024bit encryption (in which
we could then use a 160bit short exponent, perhaps).  This may be
appropriate regardless, and if things are too painful with 2048bit
encryption on the _PRE net, we may make the jump within the _PRE
net.  Otherwise, we may wait until the 0.6.1.10 release, when there
is a wider deployment of the new crypto to see if its necessary.
Much more info will be forthcoming if such a switch looks likely.

[1] "On Diffie-Hellman Key Agreement with Short Exponents" -
    van Oorschot, Weiner at EuroCrypt 96.  mirrored at
    http://dev.i2p.net/~jrandom/Euro96-DH.ps
[2] http://www.ietf.org/rfc/rfc3526.txt

In any case, lots of progress on the _PRE net, with most
communication about it being done within the #i2p_pre channel on
irc2p.

* 3) I2Phex 0.1.1.37

Complication has merged and patched the latest I2Phex code to
support gwebcaches, compatible with Rawn's pycache port.  This means
users can download I2Phex, install it, hit "Connect to the network",
and after a minute or two, it'll grab some references to existing
I2Phex peers and jump on the net.  No more hassles with manually
managing i2phex.hosts files, or sharing keys manually (w00t)!  There
are two gwebcaches by default, but they can be changed or a third
added by modifying i2pGWebCache0, i2pGWebCache1, or i2pGWebCache2
properties in i2phex.cfg.

Nice work Complication and Rawn!

* 4) ???

Thats about it for the moment, which is a good thing too, since I'm
already late for the meeting :)  See y'all in #i2p shortly

=jr
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