From: "Gary Jeffers" <CCGARY@MIZZOU1.missouri.edu>
Date: Sat, 23 Apr 94 12:41:49 PDT
To: cypherpunks@toad.com
Subject: Live code that dies. No captures!
Message-ID: <9404231941.AA09823@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


   Imagine code distributed over a network of computers over the world
that lives & that when its time dependent conversation is interrupted
- dies!

   Consider three sets of code in three computers that constitutes a
"Family"(the whole program). "Grandpa" talks to "Pa". "Pa" then talks
"Son". "Son" then talks to "Grandpa". Each "Family" member closely
monitors its cup clock & if its expected message is not received on
time - it suicides! Capture "Pa" & in seconds, "Grandpa" & "Son" take
their own lives! That is to say, they scramble certain essential parts
of themselves including cryptographic sections.

   The expected messages contain ciphertext that is generated by an
RSA/Idea scheme that changes its key at every transmission. The
"Family" would be glued together tightly by clocks & changing keys.

   The whole "Family" together would constitute a single program whose
purpose & output could not be found without analyzing the whole
"Family". An impossible to determine ( for the outsider ) member would
generate the output. The output member would change.

   A resultant of this process is that the system could not be analyzed
in its entirety. An attack to shutdown the set of computers would have
to be nearly simultaneously.

   Another trick could be use to stop a simultaneous shutdown - greatly
increase the size of the "Family". An essential trick to defeat
analysis is to have essential parts of the "Family" members encrypted
at times, so that there was no single time in which the whole "Family"
was in plaintext.

   Variations on this scheme come to mind. For instance, the route of
transmission varies & is impossible to determine by an outside invest-
igator. Another variation: redundancy could be built into the scheme
so that the loss of a computer or two wouldn't shutdown the program.
Each member could be given a CRC by its calling member at each
transmission to check for tampering. The CRC would only be for
selected sections of the member.

In order to make individual implementations practical, the "Family"
could be generated by a computer program so that less drudge work
would be done by humans.

   What purposes would this scheme be applied to? To be sure purposes
that would get a hostile response. The reader can think up his own.
This programming scheme's major virtue is that it cannot be captured
wholly intact.

   The "Family" that "Clocks", "Keys", & "Crypts" together -
"lives" together.

                                    Yours Truly,
                                    Gary Jeffers
                                    PUSH EM BACK! PUSH EM BACK!
                                    WWWAAAYYY BBBAAACCCKKKK!
                                    BBBEEEAAATTTT  STATE!