[9fans] potential patent threat to venti

["Joel Salomon" <joelcsalomon@gmail.com>]

This came up on the Freenet mailing list, but the patent issue
(approximately, retrieving data blocks over a network based on their
hashes) might affect Venti as well -- or, some predecessor to Venti
might be good prior art.

Any thoughts?

--Joel

---------- Forwarded message ----------
From: Ian Clarke <ian@locut.us>
Date: Aug 26, 2006 1:17 PM
Subject: [freenet-chat] A potential patent threat to Freenet and other
P2P networks
To: "chat Notification Requested)" <chat@freenetproject.org>,
tech@freenetproject.org


This patent purports to cover the rather obvious idea of "using
substantially unique identifiers to identify data items, whereby
identical data items have the same identifiers":

   http://www.patentstorm.us/patents/5978791.html

It was filed in October 1997, and is owned by Altnet, who are
currently using it to sue Streamcast (creators of Morpheus), and, if
they prevail or of Streamcast caves, could conceivably attack other
P2P networks, including Freenet:

   http://arstechnica.com/news.ars/post/20060815-7508.html

Now it is hard to believe that prior art wouldn't exist for such an
obvious idea, claim one is a text book definition of a hash function
which have been around for decades, claim 2 would seem to describe a
hashtable, also a notion with clear prior art going back decades,
claim 5 seems to describe the operation of a cache, and so on.

But then the claims discuss using this technique to retrieve things
over a network.  Now, one might argue that simply applying a common
computer science technique to a distributed situation is not novel (I
don't believe you can get a valid patent simply by combining two
other things you didn't invent), but it would be really useful to
find some robust examples of requesting files by their hashes over a
network that pre-date October 1997.

I have heard that the Xanadu project may have something in 1990, but
haven't got any specific references.  Is anyone aware of anything
concrete?

Ian.