ietf-dkim
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Re: [ietf-dkim] Issue #1265: Signing by parent domains

2006-05-27 08:52:09
At 7:24 AM -0700 5/27/06, Douglas Otis wrote:
On Fri, 2006-05-26 at 18:24 -0700, Paul Hoffman wrote:
 At 6:08 PM -0700 5/26/06, Douglas Otis wrote:
 >... i=somebody(_at_)some-domain(_dot_)co(_dot_)uk d=co.uk
 >
 >Currently this is permitted in the base draft which indicates the
 >parent domain is authoritative for sub-domains.

 This is absurd. Under which scenario would a signer in
 some-domain.co.uk possibly put d=co.uk in their signature?

If a bad-actor compromised a system handling the private key half of the
published key at d=co.uk, or got lucky cracking the key with a massive
bot-net or specialized hardware, then they would be able to generate
messages with email-addresses annotated as verified for _all_ of
*.co.uk.  Compromising a key high in the hierarchy, per the current
draft, would have a huge pay-off when spoofing messages.

This is in the "movie-plot terrorism" realm.
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