[Mailman-Developers] OpenPGP Integration on GSoC

[Daniel Kahn Gillmor]

On 04/11/2013 09:13 AM, Stefan Schlott wrote:

> True, the PGP file structure encapsulates the signature within the
> encryption (in contrast to S/MIME, which does it vice versa). But the
> standard PGP binary will strip both in one step, so keeping the
> signature won't work out of the box (at least I didn't manage to do
> that, I'd be really interested how to do that - would be useful for
> searchable mail archives).

It's certainly possible within the OpenPGP spec to have the mailing list
software decrypt its Encrypted Session Key (ESK) OpenPGP packet from an
encrypted message, and then add a new ESK packet (or replace the old
one) for each list subscriber.  IIUC, this should leave the original
message's signature intact.

Whether any of the various OpenPGP-related toolkits that are readily
available for python are capable of doing these operations is another
matter.

If you're playing with this stuff, i recommend reading the OpenPGP RFC,
which actually describes how all the data fits together:

  https://tools.ietf.org/html/rfc4880

you may also be interested in the PGP/MIME spec, which concerns how to
to format OpenPGP within an e-mail:

  https://tools.ietf.org/html/rfc3156

Note that the design proposed in this thread  is similar to the
schleuder2 design, though schleuder doesn't preserve the original
signer's signature either, but substitutes it with a message signature
from the mailing list itself.

This design also exposes the content of each message to the mailing list
software itself.  There are other architectures that make it so the
mailing list software never actually gets to see the content of the
message (see PSELS for an example).

	--dkg

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