>That kind of signing would prevent using i= for social networking, >because even if Grandma pays for the account (and thus the user_id >roughly identifies her), drunken Uncle Ernie lives in the basement >and sponges off her AOL subscription, and they'd both have the same >i= value.
But as you have surely seen, that happens even with a single mailbox with a single address. A fair amount of the correspondence my 12 year old daughter exchanges with her classmates comes from what is clearly a parent's address shared by the kid. On my church mailing list, there are plenty of addresses shared by husband and wife. When an ISP provides multiple addresses there's no way for the ISP to know whether they're Grandma and Ernie, or one address is Grandma's address for the church potluck mailing list and the other is the one for her leather'n'whips* list. All the ISP knows is that whoever knows Grandma's password controls all of her addresses, so as far as they can tell, it's one identity. On the other hand, as we get more extensive experience with DKIM, it seems inevitable to me that we'll build up categories of useful information that we can deduce from known signers. For example, AOL and Outblaze prevent their users from modifying the From: line, so you know that if one of them signed a message, the From: address is a stable identifier. Yahoo might put one signature on their free web mail, another signature on the paid ISP mail from Sympatico and BT, and a third on employee mail, each using an i= that is stable per signup or per employee. It's not going to be as simple as some people would evidently like it to be (in particular, i= will never be a reliable e-mail address), but DKIM is a great tool on which we can build all sorts of useful identity and reputation management stuff. Now let's see if we can clarify once and for all that d= is the identifier, and i= only means what the signer wants it to mean, so you can only interpret it to the extent you recognize the signer. R's, John * - Grandma's hobby is driving her horse cart, you pervert. _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
