Jim,
I am not sure that I understand your proposal. Are you saying the
following?: User1 sends a signedData object to User2 which includes
authenticated attributes in the signerInfo identifying User1's key
management (KM) cert and the "corporate key" KM cert associated with User1's
KM cert. The signerInfo signature binds the authenticated attributes with
the signer's identity. Based on the authenticated attributes in the
signedData object, User2 then builds an envelopedData object that includes
receipientInfos for User1's KM cert and the "corporate key" KM cert
associated with User1's KM cert.
I agree that this is a valid alternative to the proposal to include a
"corporate key" cert identifier extension in each user's KM cert (that
requires the "corporate key" feature). I believe that the extension
solution is more secure because the CA's signature of the cert tightly binds
the identity of the "corporate key" cert with the user's key material and
identity. The authenticatedAttribute method is less tightly linked and
presents opportunities for attackers to spoof the originator into creating
recipientInfos for entities' certs other than the intended recipient's cert
and (if required) the intended recipient's "corporate key" cert.
================================
John Pawling
jsp(_at_)jgvandyke(_dot_)com
J.G. Van Dyke & Associates, Inc.
================================
Return-Path: <jimsch(_at_)EXCHANGE(_dot_)MICROSOFT(_dot_)com>
From: "Jim Schaad (Exchange)" <jimsch(_at_)EXCHANGE(_dot_)MICROSOFT(_dot_)com>
To: "'Blake Ramsdell'" <BlakeR(_at_)deming(_dot_)com>,
"'jsp(_at_)jgvandyke(_dot_)com'"
<jsp(_at_)jgvandyke(_dot_)com>,
"'phil'" <pbaker(_at_)verisign(_dot_)com>,
"'Steve Russell'"
<steve(_dot_)russell(_at_)worldtalk(_dot_)com>,
"'SMIME -IETF'" <ietf-smime(_at_)imc(_dot_)org>
Subject: RE: Corporate Key mechanism
Date: Fri, 23 Jan 1998 15:21:20 -0800
It would seem to me that the the best syntax to use for the extension
would be exactly the same one as is used for the two-key this is my
encryption certificate. In the case of the gateway exploder this could
easily be done just by saying that I have a two key system and my
encryption cert is the corperate certificate.
jim