Re: [openpgp] Reducing the meta-data leak

[Daniel Kahn Gillmor <[e-mail]>]

On Mon 2016-01-04 20:23:49 -0500, Ben McGinnes wrote:
>> Removing the metadata of who a message is for seems likely to require
>> either:
>> 
>>  a) trial decryption on the recipient side (problematic for smartcard
>>     and multiple-secret-key setups, as Neal and Werner pointed out), or
>> 
>>  b) some sort of racheted shared state between sender and recipient
>>     (e.g. a briar- or axolotl-style esk, which might provide other nice
>>     features, like "deletable" ("forward-secret") messages)
>> 
>> While (b) is out of scope for us here until we get 4880bis sorted, if
>> someone wanted to experiment with that and report back, i'm sure it
>> would be interesting to several people on the list.
>> 
>> Or maybe there's a (c) option?
>
> There is, but I can't recall if I've mentioned it on this list or not,
> but I know it's been mentioned on gnupg-users because that's how I
> found out about it:
>
> http://www.confidantmail.org/
>
> An attempt at side-stepping SMTP entirely and replacing the transport
> method with one of the methods used by BitTorrent.  It relies on GPG
> for the message encryption and everything is contained within the
> encrypted zip.  The only addressing metadata is the key UID which is
> of the format of:
>
> any-damn-thing-you-like@somehost-including-tor-hidden-sites-and-i2p-it-doesn't-care
>
> It even includes a clever means of achieving forward secrecy, but
> arguably it could benefit from hiding the OpenPGP metadata a little
> better.

This sounds like an effort to hide the SMTP metadata, but doesn't
involve hiding the metadata in the OpenPGP format itself.  While i think
this is a neat idea, i'm not convinced it's addressing the same problems
that (a) and (b) are addressing.

     --dkg