Subject: [Simple] IMDN Issue 5: Changing an end-to-end signed message/cpim IM

From: Hisham Khartabil <[email-masked]>
Date: Wed, 2 Aug 2006 10:49:43 +0200

"   An intermediary that forwards an IM MAY change the recipient address
    in the CPIM To header field when forwarding (for example, a URI-List
    server changes the IM Recipient address from its own to the address
    of the final recipient of that IM for every copy it makes to be sent
    to the list members).  In this case, the intermediary MUST add an
    Original-To header field to the IM "

The problem is how to we handle message/cpim messages that are signed 
end to end?

I remember in earlier conversation with Miguel, I suggested to him 
covering the message/cpim case in his draft in sipping 
(draft-ietf-sipping-uri-list-message-07.txt). I believe this issue 
should be handled in that draft. Of course the same issue applies here 
since we are adding the Original-To header to the message/cpim part of 
the message.

Any comments?

Regards,
Hisham

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---

From: "Burger, Eric" <[email-masked]>
Date: Fri, 4 Aug 2006 05:47:55 -0400

Agreed.

-----Original Message-----
From: Hisham Khartabil [mailto:[email-masked]] 
Sent: Friday, August 04, 2006 2:34 AM
To: Burger, Eric
Cc: Miguel Garcia; [email-masked]
Subject: Re: [Simple] IMDN Issue 5: Changing an end-to-end signed
message/cpim IM

Now that I think about it, if I send an IM to a URI-List server that 
will re-populate the To header, the original IM is actually sent to the 
URI-List server (the To header carries the URI-List server address). 
The final endpoint recipients are not known yet and therefore if the IM 
is signed, it is signed with the key of the URI-List server.

Some users do know who the final recipients are and can sign the 
message for those recipients, but then there has to be multiple bodies 
in that IM, one signed for each final recipients. This hardly makes 
sense. Why would u use the URI-List server in the first place if you do 
that.

Having said that, I am considering this issue closed.

Hisham

On Aug 3, 2006, at 6:38 PM, Burger, Eric wrote:

> I would offer that end-to-end signed messages work: they prove the 
> B2BUA
> changed the message in the middle.
>
> What if the message is end-to-end encrypted?  Then the whole thing 
> blows
> up.
>
> Is this a bug or feature of CPIM?
>
> -----Original Message-----
> From: Hisham Khartabil [mailto:[email-masked]]
> Sent: Wednesday, August 02, 2006 4:50 AM
> To: [email-masked]' WG
> Cc: Miguel Garcia
> Subject: [Simple] IMDN Issue 5: Changing an end-to-end signed
> message/cpim IM
>