From: rjc@gnu.ai.mit.edu (Ray)
Date: Tue, 5 Apr 94 20:10:08 PDT
To: cypherpunks@toad.com
Subject: Proposal: some more standard remailer features
Message-ID: <9404060309.AA25086@geech.gnu.ai.mit.edu>
MIME-Version: 1.0
Content-Type: text/plain


 
   Here are some proposed remailer standards some of which I have
already implemented.

Command Formatting:

 I propose that all remailer commands start on the first non-blank line of a 
message body and start with the string '::' followed by a command-name
with no spaces in it. A command block should end when two blank lines are
encountered (which are stripped from the output) or a non-blank
line that doesn't start with '::' is encountered.

Message Encapsulation:

 I propose a standard format for recursively storing messages in
envelopes with standard formats.  Each envelope should begin with the
command "::envelope" followed by the envelope method, followed by the
body. The end of the "envelope" is specified with ::end METHODNAME
   
   The following is an envelope:

::envelope PGP [optional keyID]
----- BEGIN PGP ... -----
.....
----- END PGP ... -----
::end PGP

   I have defined several types of envelopes for the workings of
my remailer, one of them is for internal packetizing/splitting of
large messages.

::envelope PACKET part#/partmax:idstring

   For example
::envelope PACKET 1/5:<aa1024xaf#remailername>
[important data]
::end PACKET

   When creating envelopes, I escape any commands/escape chars inside them
by preceding the command line with '\'. This is removed
when removing the envelope.

   The other envelope I have defined is "PAD startline:endline" When
removing this envelope, the remailer simply deletes lines numbered
startline to endline in the message. The first line is 0.

Header formating:

  I propose the header pasting token, "::@" which gets applied
only after the message is delivered to someone (not chained).
For example
::@Subject this is the subject line
::@From    this is the from line
::@x-foo   this is the x-foo: header

  Depending on how the remailer is set up, incoming subject headers
may or may not be preserved.

Anonymous Posting:
   On any mailer which supports virtual addresses, the following special
feature shall be implemented:

   If the virtual address contains any '.' characters, the address
is first assumed to be a newsgroup. If the newsgroup exists and/or it
is not blocked by the operator, two possible actions can take place.
1) if the variable NNTPSERVER is defined, the remailer will open
a tcp connection and post the message directly to the newsgroup
specified in the virtual address
2) if not condition 1, then if the variable NEWSGATE is defined, the
remailer will mail your message to newsgroup@NEWSGATE doing any
translations on the address string as needed. e.g. NEWSGATE=cs.utexas.edu,
it sends the message to alt-news-group@cs.utexas.edu
3) else posting is disabled (visible flag in the remailer list)

Example:
::to remailer1#remailer2#talk.politics.crypto

  If asked, I will supply the magic perl subroutine needed to do
this.

[note above, I have eliminated the redundant "request-remailing-to".
When mailing through a remailer, you know the mail is going to be
remailed. ::to is easier to type]


EXAMPLE MESSAGE:

::envelope PGP
[PRETEND EVERYTHING FROM HERE DOWN IS ENCRYPTED FOR THE REMAILER]
::to ann's_remailer#darkmodem
::@Subject Hello World

<Message text>
::end PGP

when sending this out, the remailer might encrypt the message
for ann's remailer and split it into two pieces

::envelope PGP
[below is encrypted]
::envelope PACKET 1/2:#xxyyblahblah
::to darkmodem
::@Subject Hello World
<part one of the message>
::end PACKET
::end PGP

::envelope PGP
[below is encrypted]
::envelope PACKET 2/2:#xxyyblahblah
<part two of the message>
::end PACKET
::end PGP

Now when ann's remailer receives a two parted message, it queues
each piece until it gets the full message (timing out after a few
days) After all pieces are received, it removes the envelopes,
pieces the message together, and sends the message off to darkmodem
(which may be a virtual address for lightmodem#bob's_remailer)

Most of the envelope I/O is hidden from the user.


Additional ideas:

 A command ::error-to to specify where errors encountered during
processing of the message should be sent. e.g.
::error-to idstring an99999@anon.penet.fi 
or
::error-to idstring alt-waste@cs.utexas.edu

[idstring will let you know which message the error was for]

 I also propose ::route which would specify preferences preferred for
remailers when searching for other remailers to chain your
message to. e.g.
::route Private
[attempt to chain to remailers which are running on single-user non-public 
machines first]

::route Stealth
[don't use sendmail if possible, use socket-to-socket delivery
remailers first]


Comments welcome,

-Ray

p.s. most of the above proposals are not complicated to code for

-- Ray Cromwell        |    Engineering is the implementation of science;   --
-- rjc@gnu.ai.mit.edu  |       politics is the implementation of faith.     --