Re: [ietf-dkim] Replay isn't the problem, spam is the problem
2005-08-09 09:41:09
On Aug 9, 2005, at 7:34 AM, Amir Herzberg wrote:
Douglas Otis wrote:
On Tue, 2005-08-09 at 01:17 +0200, Amir Herzberg wrote:
Here you break one of the better features of DKIM. The ability to
change the recipient when forwarding the message.
I do not propose that DKIM should specificy receivers MUST discard
messages received without replay protection (and recipient
identification). I just propose we give recipients the ability to
distinguish between messages with replay protection and recipient
identification, and messages without these capabilities. So
forwarding still works, but degrades the security of the message -
to the level we have with DKIM without replay protection. What's
the problem?
I imagine you are suggesting that the RFC2821 RCPT TO: be compared to
the content of
the RFC2822 To:?
Assuming this could be made to work, then there would be no means to
known when this mechanism would create a problem, as you claim this
breaks forwarding. This would negatively impact the integrity of
email delivery, and create serious support issues. Those that opt to
disable this constraint would remain powerless at preventing a replay
attack. Not a very good choice either way.
> The DKIM already includes a date header and a expiry option.
Why would a CRL not address a replay problem?
CRL is a mechanism to revoke certificates, how is it relevant?
...
From the perspective of maintaining one's reputation, having an
ability to demonstrate a response to a complaint is important. If
you receive a legitimate complaint, the problem should be made to
stop. If using S/MIME, a CRL, or if using DKIM, the revocation-
identifier mechanism, permits the domain to halt any abuse anywhere
in transit, including replay abuse, that may be occurring. If abuse
meets a sure and rapid response, this mode of abuse should be greatly
discouraged. From a reputation standpoint, the offending domain
would be able to demonstrate their cooperation.
How does one rate limit when a message can be copied and sent through
any server where the recipient can also be changed? I assume you
want
to remove the feature where the recipient field can be changed.
No. A mail server can rate control the messages that it sends. It
cannot control what happens to them later. So that caps the
responsibility of the server, for reputation/accreditation/
compensation services. Recipients can still decide, of course, they
are willing to accept messages without replay protection, possibly
based on their source (e.g. a particular trusted, moderated mailing
list).
Now we are back to maintaining white-lists for every possible account
that may provide forwarding? As many of these domains that permit
forwarding are large, white-listing would expose the recipient
substantially. It seems you want to impose a restriction that is
sure to make forwarding email practically impossible. I am also sure
this will also reveal all those cases where the RCPT TO changes for
other reasons.
-Doug
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- Re: [ietf-dkim] What's a replay?, (continued)
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Amir Herzberg
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, John R Levine
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Amir Herzberg
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, John R Levine
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Douglas Otis
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Amir Herzberg
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem,
Douglas Otis <=
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Michael Thomas
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Hector Santos
- Re: [ietf-dkim] Replay isn't the problem, spam is the problem, Douglas Otis
- Re: DKIM implementations SHOULD support replay protection (was: Re: [ietf-dkim]Re: Replay attacks and ISP business models, Dave Crocker
- Re: [ietf-dkim] Re: Replay attacks and ISP business models, Amir Herzberg
[ietf-dkim] Re: Replay attacks and ISP business models, Douglas Otis
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