I fail to see any relevance here? Go out to your user pool show them the headers and ask them what they signify. Chances are "not much".
From: [EMAIL PROTECTED] Sender: [EMAIL PROTECTED] Good DKIM sig from bar.com Means that bar.com signed on behalf of (purportedly) [EMAIL PROTECTED] and when asked will verify that yes indeed we sent that message. It has squat all to do whether the letter is a 419er, Viagra or get rich quick pumping stock. Expecting end users, remember we are an ISP, to understand DKIM + SSP is far beyond anything we could imagine. Thanks, Bill Oxley Messaging Engineer Cox Communications -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Charles Lindsey Sent: Thursday, November 30, 2006 5:55 AM To: DKIM Subject: Re: [ietf-dkim] Re: Role of Sender header as signing domain On Wed, 29 Nov 2006 16:50:24 -0000, william(at)elan.net <[EMAIL PROTECTED]> wrote: > On Wed, 29 Nov 2006, Charles Lindsey wrote: > >> On Tue, 28 Nov 2006 15:42:11 -0000, Scott Kitterman >> <[EMAIL PROTECTED]> wrote: >> >> >>> 2822.From is the only identity that is reliably displayed to the end >>> user. >> >> I utterly fail to see why what is displayed to the user is of the least >> relevance. > > Charles is correct. The way protocol is layed down right now what is > displayed to the user is irrelevent to the core. It only becomes relevent > with the the policy part which is supposed to be the one trying to > protect > against phishing. Also note that any MUA-based anti-spam systems that may > use the core would look at what it says and therefore if other header > field > like Sender is listed its quite likely to be displayed. > Ah! I think I see now what Scott and Eliot are getting at. Suppose we have: From: [EMAIL PROTECTED] Sender: [EMAIL PROTECTED] with good signature by bar.com The verifier informs the recipient that the message was signed by bar.com, and is confused because he sees no header mentioning bar.com. Or it reports a failed signature by bar.com, and the user is even more confused. I.e., he is supposing that the user is merely informed of what signatures are present and it is left to him to inspect the displayed headers to see whether he needs to be alarmed. I find that a very poor way of communicating to the user, as others have pointed out (though I don't go along with Doug's expectation that the user's MUA will go trawling through his address book). So let us step back a moment and see how this communication might take place. There are two cases: 1. The MUA has been specially adapted to work with DKIM 2. The MUA has not been specially adapted We are supposed to be designing a system which will work with existing MUAs (i.e. case 2), so in that case the verifier's policy module can only communicate with the user via the body of the message - rather like those irksome systems which add long paragraphs to the end of messages to inform you of all the viruses they did or didn't detect. So in that case it is up to the policy module to describe its suspicions in a manner the user can understand whether he can see all the relevant headers or not. So it might say "This message was sent by [EMAIL PROTECTED] (good signature by bar.com) but you should notice that the From: address made no mention of bar.com." or "This message was sent by [EMAIL PROTECTED] apparently on behalf of [EMAIL PROTECTED], but there is no valid signature from either of them." OTOH, if one can assume an adapted MUA as in case 1, then presumably the communication could be by some other channel (possibly using the headers), but such an MUA would, in any case, display all headers relevant for understanding the report from the policy module, including the Sender if appropriate. -- Charles H. Lindsey ---------At Home, doing my own thing------------------------ Tel: +44 161 436 6131 Web: http://www.cs.man.ac.uk/~chl Email:[EMAIL PROTECTED]: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K. PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5 _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
