From: Matt Carpenter <mcarpent@Dusk.obscure.net>
Date: Wed, 24 Jul 1996 19:57:28 +0800
To: cypherpunks@toad.com
Subject: emscrypt 0.01 ALPHA
Message-ID: <199607240857.DAA06070@Dusk.obscure.net>
MIME-Version: 1.0
Content-Type: text/plain


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I finally managed to find some time to do a little testing of emscrypt and
make some of the changes that were suggested here earlier.  It is still
rather ugly and I haven't added many of the features/capabilities I hope to
eventually implement.  But I'm making it available so that people can play
with it if they want.  It looks like I'm going to be very busy for at least
the next month trying to finish up the work for my master's degree, so I
probably won't be making any major changes for a while.

emscrypt's purpose is to automatically run PGP signed scripts received by 
e-mail and return the results to the submitter.  emscrypt is a heavily
mutated version of morepgp, originally by Jason Steiner and modified by Greg
Spencer.

Please realize that this program has NOT undergone extensive testing, so you
may encounter strange behaviour.  Make sure you read the documentation that
exists.  Using this program may make your system insecure, especially
if you don't follow the installation procedure carefully.  Use at your own
risk.

You should be able to find emscrypt and some documentation at:
http://www.bmen.tulane.edu/~carpente

Look under the "Other random projects or possibly useful stuff" heading.


In order to try out emscrypt you need the following:

* Perl -- emscrypt is written in Perl.

* PGP 2.6.2 -- Other versions may work, but I haven't tested them and
emscrypt relies strongly on knowing the format of the PGP output messages.

* Procmail -- For passing incoming mail to emscrypt.  This can be accomplished
in other ways, but at this point I haven't tried any of them.  If you don't
have procmail you can still play with emscrypt by piping messages to it
manually.  I strongly suggest you do this anyway, to make sure you trust
emscrypt to answer incoming mail.



Here are the major things that have changed with emscrypt since I described
it here a while ago:

There are now two required headers which must be included in the body of
the signed message: 'Reply-To:' and 'PGP-Key-Fingerprint:'. Both must appear
before the beginning of the script.  The beginning of the script is
considered to be anything other than the above headers, blank lines, or
lines that begin with '::' but that are otherwise empty.  Duplicate headers
will generate an error and prevent the script from executing.  Case within
the headers is not important.  (You are free to use eLiTE d00dz
capitalization techniques, just don't try to use kRe8yv sP3lliNg5.)

'Reply-To:' must be followed by a valid e-mail address, otherwise you won't
get your results. (emscrypt will also recognize a 'Request-Remailing-To:'
header in place of 'Reply-To:'.  I added this so that emscrypt could be
treated as a "remailer".  The idea is that you could use software such as
premail to automate the generation of messages going to emscrypt, so that
you don't have to do the signing/encrypting manually.  Then you could just
send a script to yourself, "chaining" it through your emscrypt "remailer".
But I don't think this will work without slight modifications to the
remailer message generating programs, since emscrypt requires the
'Request-Remailing-To:' header within the signed body of a message (it would
also be nice if the 'PGP-Key-Fingerprint' header could be automagically
included)).

The 'PGP-Key-Fingerprint:' header gives the fingerprint of the key used to
sign the message and which will also be used to encrypt the results.  It
must also be included within the signed body of the message.

Most of the other changes involved minor debugging and general clean-up (not
that I consider it clean now).  I also improved the error handling a little,
but it needs more work, too.  Right now emscrypt generally tries to generate,
encrypt, and mail an error report if things go wrong.  If that doesn't work,
then it saves an error message to a log file.

If you find any problems, please let me know. Comments, suggestions, 
etc. are also welcome.


Thanks,

- --Matt

- --
mcarpent@mailhost.tcs.tulane.edu


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