No Subject

On Aug 18, 96 11:12:16 am, Joel M Snyder, Now Overwhelmed Again wrote:

> Back to the original topic: email-to-snail-mail.  That's not hard,
> technologically.  The problem as I see it is billing.  If I were to offer
> such a service, I'd want to keep my cost to the consumer low, on the order
> of $0.75 to $1.00 per message, with marginal charges for additional pages. 
> I might possibly barely be able to find some slave labor to make a profit
> at doing it, IF I HAD THE VOLUME (which I probably wouldn't), but the
> overhead of setting up a billing arrangement with every TDH who wants to do
> it would eat the profits up instantly.  
> 
> It's difficult to conceive of a setup which a technomad would use in
> sufficient volumes to be cost-effective.  


How about the sender provides a Digicash e-cash payment for the
appropriate amount with each message, kind of like a electronic postage
stamp?  A script on the receiving side could automatically check the
payment amount, bouncing the message back to sender with an
"insufficient payment" message if necessary.  Or you could use a web
page to submit messages and payments.  Either way no one needs to worry
about billing, account tracking, etc.  Payment/billing is taken care of
immediately.  Of course, there is some overhead with the fees on e-cash,
but it probably would be more cost effective than other methods.


P.S. I have an alpha version of a program which may be of interest to
technomads: it automatically executes scripts received by email from a
remote machine and then mails back the results.  The scripts (shell
scripts, perl scripts, or whatever) are encrypted and signed with PGP
before being sent to provide security and prevent unauthorized users
from executing scripts on your machine.  The program runs on unix
systems, and submissions can be from anything that runs PGP and is able
to send email.  See:

  http://www.bmen.tulane.edu/~carpente/emscrypt/emscrypt.html

for more info.


--Matt

--
mcarpent@mailhost.tcs.tulane.edu    PGP mail preferred, finger for public key.

-----BEGIN PGP SIGNED MESSAGE-----

From: Rick Campbell <campbell@c2.org>
To: Alan Horowitz <alanh@infi.net>
CC: cypherpunks@toad.com
In-reply-to: Alan Horowitz' message of "Sun, 18 Aug 1996 23:52:05 EDT."
             <199608190352.XAA07594@larry.infi.net> 

    From: Alan Horowitz <alanh@infi.net>
    Date: Sun, 18 Aug 1996 23:52:05 -0400 (EDT)

    P.S. I have an alpha version of a program which may be of interest to
    technomads: it automatically executes scripts received by email from a
    remote machine and then mails back the results.  The scripts (shell
    scripts, perl scripts, or whatever) are encrypted and signed with PGP
    before being sent to provide security and prevent unauthorized users
    from executing scripts on your machine.  The program runs on unix
    systems, and submissions can be from anything that runs PGP and is able
    to send email.  See:

Does your mechanism do anything to prevent replay attacks?

			Rick

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Version: 2.6.2

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Pg8QdEWcteo=
=ghZA
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Rick Campbell writes:

>>     P.S. I have an alpha version of a program which may be of interest to
>>     technomads: it automatically executes scripts received by email from a
>>     remote machine and then mails back the results.  The scripts (shell
      ... 
> 
> Does your mechanism do anything to prevent replay attacks?
> 
> 			Rick

Alan apparrently forwarded my message from technomads to cypherpunks,
but since I'm on cypherpunks too, I got this message.  Anyway, yes it
does have a simple replay attack prevention mechanism.  It keeps track
of the most recent time and date stamp from the PGP signature info and
refuses to executed any message that doesn't have a stamp more recent
than previously executed script.  This simple mechanism can cause
unwanted rejection if scripts are received out of order, but multiple
scripts can be batched into a single message to help overcome this.

See the following URL for a discussion of known limitations and security
concerns with emscrypt:

  http://www.bmen.tulane.edu/~carpente/emscrypt/emscrypt_doc.html#limits


--Matt

--
mcarpent@mailhost.tcs.tulane.edu    PGP mail preferred, finger for public key.

I didn't write the message, "I have an Alpha...."