Thanks for your comment, Hector and Alessandoro. I understand your point. First, Alessandoro, let me reply to your comment.
Yes, very true, it is recipients' choice to discard messages. But in fact, that choice is lost for now because our Ministry does not allow that. My idea was to build another level of ground where the author, recipients and the Ministry can agee on, "if-no-sig then discardable". And I see your point, Hector. If we draw a line between Sig and No-sig, that would allow broken signature to be accepted. But as you poited out, bad guys still remain in legacy operation, so the line between Sig and No-sig works for the time being. I know that it is not the best way to do it, but it could be a practical step to the wider adoption. Because if that option gets valid, I am sure more authors would choose it at least here in Japan. I don't think that undermines the effectivenes of DKIM, because one can always rewrite his ADSP 'discaradable' if the bad guys start spoofing with forged signatures. Well, it's just a newbie's idea, so may be totally unacceptable. But please understand that we're heavily committed. Gotta find a way through. Tsuneki Ohnishi infomani@ Inc. On 2010/11/22, at 18:16, Alessandro Vesely wrote: > As an alternative, it is the recipients who may eventually decide they > are not interested in receiving unsigned contributions to their > inboxes, unless they have other means to identify those messages. > IMHO, such decision should be made by each recipient individually. On 2010/11/22, at 14:49, Hector Santos wrote: > Tsuneki Ohnishi wrote: > >> So, my point is that what do you think of the idea to have >> an new entry in ADSP "discard-if-no-sig", which allows >> senders to declare messages without DKIM signature should >> be discarded? >> >> If that's possible, it makes our job a lot easier and faster. > > Hi. > > You are basically asking to make a distinct difference between: > > 1) a real no signature message versus > 2) a message who's signature is broken (invalid). > > The DKIM specification says that a broken signature is the same as no > signature message. > > It is important to know the difference because if you are concern about a > Real No-Sig versus a Broken one where a Real No-SIG is discarded but a Broken > one is not, then whats to stop the Bad Guy from adding a broken signature by > design and for the sole purpose of making sure the message is now > indeterminate and you don't filter it? > > The problem with DKIM is the is the "stuff in the middle" - A real no-sig > message can be made to work, as well as when there is a valid signature. > > It the faults of the system that is challenging - what do you do with > failures and what makes it even more difficult is the specifications has > evolved to one where where any system, middle-ware or hop, can break or > remove an author domain signature without restrictions. This was done to > appease the LIST managers, 3rd party signer and the reputation market. > > IMO, I think DISCARD should cover what you want, but you have to view it as a > strong policy with no exceptions, i.e., a broken signature is just as bad as > no-signature and more importantly, no interference or 3rd party signers can > override the message author domain security expectations. > > If you allow for broken signatures to be "acceptable" partially or otherwise > in an ADSP setup, then it just confuses the intent and it potentially feeds > bad guys to give you broken signatures because that is "OK" by you. > > Right now, there is no incentive for bad guys to adapt or change. They can > remain in legacy operations (no signature) because there is no wide adoption > or foundation for DKIM policies or the handling of policy faults. > > Having a "MUST SIGN" policy widely adopted (and supported) would begin to > make a change in legacy operations. They will most likely avoid your POLICY > protected domain. But if you allow for broken ones, then they can adapt by > adding a spoofed but broken signature. > > -- > Hector Santos, CTO > http://www.santronics.com > > > > --------------------------_____________________________ 株式会社インフォマニア ≫ http://www.infomania.co.jp/ 代表取締役 大西恒樹 ≫ TEL 045-914-5304 FAX 5404 迷惑メールフィルター ≫ http://www.answre.jp/ Pizzeria マルターノ ≫ http://www.martano.jp/ twitter アカウント ≫ mjwords --------------------------------------------- _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
