Re: [dane] Digest Algorithm Agility discussion (checkpoint)
Viktor Dukhovni <viktor1dane@dukhovni.org> Tue, 18 March 2014 14:38 UTC
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Date: Tue, 18 Mar 2014 14:37:59 +0000
From: Viktor Dukhovni <viktor1dane@dukhovni.org>
To: dane@ietf.org
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References: <alpine.LFD.2.10.1403171440540.32251@bofh.nohats.ca> <20140317222320.443521AC59@ld9781.wdf.sap.corp> <20140317225329.GK24183@mournblade.imrryr.org> <20140318112647.885B21190C03@rock.dv.isc.org> <20140318141356.GO24183@mournblade.imrryr.org>
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Subject: Re: [dane] Digest Algorithm Agility discussion (checkpoint)
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Thanks to everyone who contributed to this point. My conclusions so far: - Since "local policy" may exclude an arbitrary subset of the digest algorithms from consideration, whether the digest algorithm employed by clients is as I suggest, or not, server operators MUST apply the SAME set of digests to all objects published in a TLSA RRset, since otherwise the "visibility" of objects in the RRset will be client dependent. - Given the above clients either MAY or SHOULD apply the algorithm I propose, it provides incremental benefit before weaker algorithms are dropped, and reduces risks to servers that publish weaker algorithms. For example, with opportunistic TLS, client and server implementations can safely leave weaker cipher-suites at a low priority on their cipher-lists, because these will not be chosen when stronger options are available. When nothing better is available, these are at least better than cleartext. If "local policy" per 6698, includes the possibility of "adaptive local policy" that depends on the server's TLSA RRset content, then my proposal is already an implicit MAY per 6698. I'd like to propose to elevate it to a SHOULD, while emphasizing the MUST for the server to publish cross-product TLSA RRsets when employing multiple digests. Reminder: the proposal is that clients SHOULD apply some local ranking to the digest algorithms, and only use those records for each (usage, selector) combination that either have a matching type of Full(0) or have the best ranking among all digests used with that (usage, selector). Clients SHOULD have a way to completely disable algorithms. -- Viktor.
- [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Wouters
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Hoffman
- Re: [dane] Digest Algorithm Agility discussion Paul Wouters
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Hoffman
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Wouters
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Hoffman
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Martin Rex
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion (c… Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Jim Schaad
- Re: [dane] Digest Algorithm Agility discussion (c… Paul Hoffman
- Re: [dane] Digest Algorithm Agility discussion (c… Andrew Sullivan
- Re: [dane] Digest Algorithm Agility discussion (c… Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion (c… Scott Rose
- Re: [dane] Digest Algorithm Agility discussion (c… Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion (c… Scott Rose
- Re: [dane] Digest Algorithm Agility discussion Wes Hardaker
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Peter Palfrader
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Peter Palfrader
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Peter Palfrader
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Mark Andrews
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Paul Wouters
- Re: [dane] Digest Algorithm Agility discussion Viktor Dukhovni
- Re: [dane] Digest Algorithm Agility discussion Peter Palfrader
- Re: [dane] Digest Algorithm Agility discussion Wes Hardaker
- Re: [dane] Digest Algorithm Agility discussion Wes Hardaker