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Subject: RE: Content ( was RE: [emergency-comment] RE: [CAP] RE: CAP-list digest...)
Art Botterell wrote: >>At 5:29 PM -0500 3/5/04, Bob Wyman wrote: >> ... the CAP specification *DOES NOT* tell me where to put them if I >>am trying to pass a CAP message without SOAP. > That's right, it doesn't.... And after discussing this very > question at some length a number of months ago, the members > of the TC decided that it lay outside the scope of the CAP > spec and more properly in the scope of specifications for > a particular transport context. So, what you're saying is that CAP *does not* provide any mechanism or facility for doing authentication of messages in a manner which is independent of the transport mechanism. If you want signed messages, you must use a transport, like SOAP, that supports signed messages. Thus, the odd mention of WSSE in the specification is really just a non-normative hint to users of SOAP which reminds them that they can use SOAP to transport and sign CAP bodies. CAP itself, doesn't deal with the issue of signing CAP messages nor does it deal with encryption. This sounds a bit odd since in Section 1.1 of the CAP specification it is explicitly stated that CAP capabilities include: "Facility for digital encryption and signature capability". In fact, it appears that encryption and signatures can only be had by using facilities that are *not* provided by CAP. If anything, the most CAP does is avoid interference with these non-CAP facilities. Given this, it would seem to make sense to remove the statements in Section 1.1 that promise encryption and signatures... CAP doesn't deliver on these promises. Am I reading this correctly? > But in the meantime I've yet to hear of any actual > attempt at implementation that's failed for lack of > this feature, and there have been a number of implementations, > so I think it might be premature to cast the discussion > in catastrophic tones. As I've mentioned in earlier messages, I am prepared to provide an Internet-Scale facility for the collection of and distribution of CAP messages. However, given that the content of CAP messages is very sensitive (i.e. it involves folk's lives), I'm finding it hard to understand how such a facility can be provided *without* a mechanism for authenticating messages and providing for non-repudiation. The issue is not one of technology -- it relates to ethics, law, risk management, and the methods of hackers and terrorists... If the "actual" author of a message can't be reliably established (i.e. via signatures), then whoever was "last in the chain" for handling the message ends up being responsible for its content... Given that we're an intermediary, we would end up "owning" every message that passes through us. We would also become an obvious target for anyone wanting to insert forged data into the system. That is not a good thing. Authentication is not only useful to the end users of the system. It is also useful to the intermediaries since authentication allows them to wave off responsibility for the content of messages passed and it makes them a less useful focal point for malicious attacks. (Note: Pay attention to this last point... The network, the channel, is *less likely to be attacked* if signatures are supported...) In Section 1.2 of the CAP spec it is indicated that CAP was at least partially motivated by a desire to deliver on the recommendation of the National Science and Technology Council which urged that "a standard method should be developed to collect and *relay* instantaneously and automatically all types of hazard warnings ... into a wide variety of dissemination systems". The key to my issue is the word "relay." For a relay to be deployable with this sort of data, there *must* be mechanisms for establishing the true source of CAP messages in a manner which cannot be repudiated. > Nonetheless, it sounds like what you're saying boils down > to a suggestion that CAP would be stronger if it provided > an explicit internal mechanism for digital signatures. > That's certainly a question the TC could revisit. If CAP is to provide a transport-mechanism-independent format for Alerts and also provide for "encryption and signatures" then it *MUST* explicitly deal with the question of authentication, encryption, etc. in a channel independent manner. Thus, I'm not suggesting this as a way to make CAP "stronger" (even though that would be the case) rather, I'm suggesting that the professed goals of CAP can only be achieved by taking this step. bob wyman (Note: This message is cc'd to emergency-comment not as a solicitation for input but rather as a comment. I understand that comments will travel over other channels...) -----Original Message----- From: cap-list-admin@incident.com [mailto:cap-list-admin@incident.com] On Behalf Of Art Botterell Sent: Friday, March 05, 2004 6:26 PM To: cap-list@incident.com Subject: RE: Content ( was RE: [emergency-comment] RE: [CAP] RE: CAP-list digest...) At 5:29 PM -0500 3/5/04, Bob Wyman wrote: > ... the CAP specification *DOES NOT* tell me where to put them if I >am trying to >pass a CAP message without SOAP. That's right, it doesn't. Again I'll point out that CAP does not specify any particular transport arrangement. And after discussing this very question at some length a number of months ago, the members of the TC decided that it lay outside the scope of the CAP spec and more properly in the scope of specifications for a particular transport context. In the SOAP case, for example, the security design was the output of a standards process. In the DMIS case it was a "designer's choice" (albeit still standards-based and open) by that network's implementer... as was also the case for the MyStateUSA and Hormann America implementations and the earlier ComCARE/Orillion deployments. Nonetheless, it sounds like what you're saying boils down to a suggestion that CAP would be stronger if it provided an explicit internal mechanism for digital signatures. That's certainly a question the TC could revisit. But in the meantime I've yet to hear of any actual attempt at implementation that's failed for lack of this feature, and there have been a number of implementations, so I think it might be premature to cast the discussion in catastrophic tones. - Art _______________________________________________ CAP-list mailing list CAP-list@incident.com http://www.incident.com/mailman/listinfo/cap-list This list is not for announcements, advertising or advocacy of any particular program or product other than the CAP itself.
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