Re: [Endymail] Hashes of key as addresses

[Michael Kjörling <[e-mail]>]

On 29 Aug 2014 09:37 -0400, from [e-mail] (Phillip Hallam-Baker):
> On Fri, Aug 29, 2014 at 5:11 AM, Michael Kjörling <[e-mail]> wrote:
>> On 28 Aug 2014 19:23 -0400, from [e-mail] (Phillip Hallam-Baker):
>>> Using hashes of keys as addresses is very powerful. There are
>>> basically three types of address in such schemes:
>>> 
>>> 1) traditional human readable
>>> 
>>> 2) hash of key
>>> 
>>> 3) Traditional human readable + hash of key.
>>> 
>>> 
>>> So in PPE we use all three in different situations:
>>> 
>>> 1) ACAIEA-FONPAC-5AC6LFA-K4ACHC-EAJWAHN-VPAM4A-COYPAO-VAA
>>> 
>>> 2) [e-mail]
>>> 
>>> 3) ACAIEA-FONPAC-5AC6LFA-K4ACHC-EAJWAHN-VPAM4A-COYPAO-VAA?[e-mail]
>> 
>> Does this scheme not imply that everyone who wants to validate an
>> address, or know to where to pass a message given an address, needs to
>> either (a) query some form of central repository where all address
>> (hash)es are registered, or (b) have a local cache of all valid
>> address (hash)es?
> 
> No, it implies some mechanism for resolving the hashes. But that does
> not need to be centralized.

Fair enough, but how would you resolve such a hash without
connectivity?

We know that traffic analysis is being done on a massive scale, and
have good reason to believe that encrypted traffic is routinely and
specifically targeted for storage for possible later analysis.

As it stands, with SMTP, assuming transport security (_proper_
STARTTLS, for example), it seems about the most someone listening in
can figure out is that someone is sending e-mail to a particular
domain (say, by matching DNS MX RR lookups with subsequent SMTP TCP
connections). This leaks a small amount of metadata, but that can be
mitigated by sharing SMTP hosting and email address domains with
others. I would argue that any replacement (the purpose of which is
end-to-end security) should not leak _more_ metadata to any reasonable
attacker, ideally including an active attacker able to do network
packet injection.


> One way that works very well is to use QR codes in an in-person
> meeting. Web of Trust never worked the way PhilZ wanted. But we didn't
> carry supercomputers with cameras (aka smartphones) then.

Far from everyone does, even today. [1] Should the protocol be
designed to essentially require such?


> There does not need to be a central repository. There does not even
> need to be global connectivity.

Then how would you propose to validate a hash, or given a hash, send a
message to it, without some sort of connectivity to some sort of hash
repository?


[1] Thu, 4 Sep 2014 13:18:56 +0000, http://mailarchive.ietf.org/arch/msg/endymail/qIjDw--NOtG0JFbqHJHvbHKVPeM

-- 
Michael Kjörling • https://michael.kjorling.se • [e-mail]
OpenPGP B501AC6429EF4514 https://michael.kjorling.se/public-keys/pgp
                 “People who think they know everything really annoy
                 those of us who know we don’t.” (Bjarne Stroustrup)