Yakov,
Your own post, "[Asrg] News Article - MailBlocks, Patents and Prior
Art", 19 May 2003, quotes an article about Mailblock and prior art
claims by David F. Skoll and Brad Templeton. Perhaps these claims
should be added to your collection prior art for the Mailblock pattents.
Reference to Skoll's work:
http://groups.google.ca/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=56luge%246on%40bertrand.ccs.carleton.ca
and the thread "[Asrg] Not again - another challenge/response patent".
Templeton's own page:
http://www.templetons.com/brad/spam/challengeresponse.html
Harry Tabak
Yakov Shafranovich wrote:
David,
I updated the web page
(http://www.solidmatrix.com/research/asrg/asrg-ipr.html) to include
prior art. If anyone else knows of any IPR information including prior
art, please post to the list.
Yakov
At 12:29 PM 6/2/2003 -0400, David Wheeler wrote:
Vern Paxson -
Thanks for tracking patent claims. Could you also
please track evidence of previous work ("Potential Prior Art"),
so that those who are interested in potentially-invalidating
prior art can learn of them too? I think that would be very
useful information for anyone doing anti-spam research.
Hopefully, others on this list will help fill out any entries.
Here are some potential prior art entries for the Mailblocks patent,
I'm sure others here can add a few:
<p>
Challenge-response is simply an automation of the "Halt! Who goes
there!" challenge that guards have been issuing for millenia.
Thus, this patent can be challenged as a trivial automation of
previous approaches that have been used for millenia.
<p>
In 1992, Cynthia Dwork and Moni Naor of IBM
described a challenge-response system in which the sender
would be asked to process a particular solution before
the receiver would accept the email
<a href="http://research.microsoft.com/research/sv/PennyBlack/junk1.pdf";>
[Dwork 1992]</a>.
This work was publicly presented at Crypto '92.
<p>
On May 26, 1996,
<a
href="http://groups.google.com/groups?selm=4o8cqk%248ah%40dwst13.wst.edvz.sbg.ac.at&output=gplain";>
Otmar Lendl (lendl at cosy.sbg.ac.at)
posted how to implement a challenge-response system using procmail</a>.
This was publicly posted to the newsgroup "news.admin.net-abuse.misc"
as the subject "Re: Unsolicited junk email from
exd48265(_at_)interramp(_dot_)com",
message-ID
<4o8cqk$8ah(_at_)dwst13(_dot_)wst(_dot_)edvz(_dot_)sbg(_dot_)ac(_dot_)at>#1/1.
This was a simple script that accepted email that accepted email
if it came from certain sources or included a special password in the
"Subject" line; otherwise, a challenge was replied back to the
original sender.
This posting included the code to implement the approach, as a response
to another query in the newsgroup.
Indeed, there are hints that others have implemented challenge-response
systems far earlier as well.
Hope that helps, and thank you.
--- David A. Wheeler
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