We have avoided catastrophic failures in the past by designing our systems in
such a way that gradual transition is possible.
For example in 2010 the Server Gated Crypto roots will expire and it will no
longer be possible for a user of a Windows 98 machine with the 40-bit export
encryption stack to visit their bank using 128-bit cryptography.
If we had a situation where nobody could securely use 128 bit security until
every bank in the world had upgraded to support 128 bits we would today be in a
really bad mess.
The argument Dave appears to be making here is that because we have never
succeeded in the past lets plan to make sure we fail this tim by ignoring an
issue we can solve today. I don't accept the premise and I don't accept the
argument. The conclusion is also wrong.
-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Dave Crocker
Sent: Wednesday, February 28, 2007 1:48 PM
To: Eric Allman
Cc: IETF DKIM WG
Subject: Re: [ietf-dkim] Issue 1386 and downgrade attacks
Eric Allman wrote:
[By the way, there was also some confusion about whether
transitions
are
O(years) or O(days). Changing selector records is O(days),
whether or
not those selectors change algorithms, but changing algorithms
requires software updates and hence is O(years).]
Important distinction. Thanks.
It's probably worth noting that a catastrophe with a deployed
algorithm, so that a rapid transition is required, has no
precedent in the large-scale, open Internet, and probably
would take considerably more effort and mechanism than
anything we are discussing here.
As such, building in anything designed a) to deal with highly
problematic, systemic failures, and b) incurring overhead for
most/much regular traffic in anticipation of that catastrophe
is probably not such a good idea.
As we have seen in other such algorithm transitions for
mechanisms in end-points -- rather than infrastructure --
they tend to have a distinctive
characteristic:
While it is O(years) to achieve very broad adoption, it
can be O(months or even weeks) to gain a useful degree of
adoption, within smaller communities of interchange.
In general, this means that slower algorithm transitions are
acceptable and can be handled in the same way as we handle
other transitions on the Internet.
None of them include a publication mechanism.
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net
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