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Re: [ietf-dkim] Structure of the threat analysis...

2005-10-12 08:53:33
Stephen Farrell wrote:


Hi All,

I've just been reading the threats draft, which after (or maybe
even before!) the charter should really be our #1 thing at the
moment (given that we're gated on progress there).

First, I like the document - I think it does cover the main
threats that will concern us. However I'd like to suggest an
alternative structure which may make it easier to maintain
and which would allow the reader to be clearer that the
analysis has good "coverage" (and hence get us past the IESG
more easily;-).

One of the biggest problems with threat analyses is that there is no agreement on what they should contain nor what their structure should be. I believe the Security Area realizes this and will be working to correct that. In the meanwhile, a structure was suggested by Russ Housley which is described in http://mipassoc.org/pipermail/ietf-dkim/2005q3/000033.html which formed the basis for the threat analysis I published. I (and many others I have corresponded with) feel that it's most important that the document be satisfactory to Russ, because he will be the one to take our request for chartering to IESG.

I have been planning on a minor revision of the threat document before the revised draft cutoff (Oct 24), but can do something more aggressive if it's a real improvement that will move us closer to chartering.

So I would like a reading from Russ as to whether he views the structure you propose as an improvement, and whether the current structure is adequate, before making a sweeping change such as this.

Also, regarding the example you gave:

Vulnerability: dkim servers could be a poster-child for
timing analysis attacks aimed at getting the server private
key - they're signers which sign anything (and loads of it)
and where adversaries can be easily situated on both sides
of the signer. If this could be done then the server private
key would be compromised from the network.

There is the question of whether this document is describing (1) the threat environment into which we're inserting DKIM, or whether it describes (2) the threats that exist in the presence of DKIM (perhaps those motivated by DKIM), or both. I believe that this document should emphasize (1), and that (2) belongs in the Security Considerations section of the DKIM draft(s), even though section 6 of the current draft does describe some of the latter. If you accept this philosophy, the above threat doesn't belong in the document because the private keys don't yet exist.

-Jim
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