> The signer most certainly CAN attack, but what he is attacking is not > DKIM; rather it is the recipient, or Ebay, or lenient MTAs. DKIM is, in > fact, his weapon of attack.
Right, but the point is that, with DKIM (as Murray says, this attack can be mounted with or without), the signing domain is relying on its own reputation, not that of the "fake" From. That mitigates things in two ways: 1. There's really no difference between using "d=badguy.com" to sign "From: [email protected]" and then adding "From: [email protected]" later, and using "d=badguy.com" to sign "From: [email protected]" in the first place. No advice in this regard addresses the second case anyway. 2. Signers that do this will quickly get bad reputations, and will never have had strongly good ones in the first place. It's never eBay's reputation that's relevant here anyway. Given all that, having us describe the problem is sufficient, and that's exactly what the WG consensus has us do. Barry, as participant _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
