From: Charles Lindsey (chl@clw.cs.man.ac.uk)
Date: Mon Jun 07 1999 - 06:00:05 CDT
In <19990604134929.42449@main.templetons.com> Brad Templeton <brad@templetons.com> writes:
>On Fri, Jun 04, 1999 at 10:49:30AM +0200, Brad Knowles wrote:
>>
>> You say that we're talking about a server-side protocol here. If
>> that's the case, then typically only injection agents are going to be
>> doing signing, and for example our news server would sign each and
>Actually, no, an injector can sign (and will sign if the site is active
>enough to install a new, signing injector, AND the site has some way to
>authenticate the user it is signing for) but users will also sign, passing
>to an injector that won't muck the signature. (This may not be their
>injector, but that doesn't matter, once you have signature, you can have
>open injectors which take validly signed postings from anybody on the net.)
I agree. Sometime the injector will sign; sometimes the poster. Sometimes
the server will verify; somethine the (paranoid) reader himself. Signing is,
after all, basically an end-to-end protocol.
But this means that whatever scheme we use must be proof agains munging by
injectors and newsreaders, as well as transports. See my story about Date
munging by CNEWS in my previous message.
>To do that, it is important to have key revocation. If your key is compromised,
>you get it revoked, and you get a new one. You cancel the forgeries using
>your new one. The ability to UNDO problems in this fashion lets you have
>a net where security does not put a big burden on people.
OTOH, I do not think it so essential to have instant regognition of
revocations. Most people revoke because they want to start using a new
key, and they just stop using the old one. It is rare for a key to be
truly compromised and if, for example, it happens to a moderator's key,
then he posts a notice to the moderated group (complete with revocation
certificate) so that the readers of that group know (and che ontinues to
do so so long as forgeries with the old key continue to be posted).
-- Charles H. Lindsey ---------At Home, doing my own thing------------------------ Email: chl@clw.cs.man.ac.uk Web: http://www.cs.man.ac.uk/~chl Voice/Fax: +44 161 437 4506 Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K. PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5