Re: [dane] Lukewarm discussion: DANE for opportunistic TLS protocols
Viktor Dukhovni <viktor1dane@dukhovni.org> Sat, 15 February 2014 02:13 UTC
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Date: Sat, 15 Feb 2014 02:13:32 +0000
From: Viktor Dukhovni <viktor1dane@dukhovni.org>
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Subject: Re: [dane] Lukewarm discussion: DANE for opportunistic TLS protocols
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On Fri, Feb 14, 2014 at 04:48:32PM -0800, Paul Hoffman wrote: > Personally, I don't care about MITM protection if it comes at > the cost of getting more organizations to turn on opportunistic > crypto. One quick comment, there is no conflict between opportunistic DANE TLS and "pre-DANE" opportunistic TLS. So I would take issue with "at the cost of". If anything the two are symbiotic. The first step for an SMTP server operator towards greater channel security is to enable STARTTLS if they have not already done that. At that point all TLS-enabled clients (be they DANE aware or not) will generally send email over unauthenticated TLS. Once the server operator determines that TLS is working satisfactorily for all clients (observed over weeks to months) he may decide to enable DNSSEC for his domain and if that works out OK, later publish a TLSA "3 1 1" RRset that matches his server certificate. The certificate will not capriciously expire causing an SMTP outage, it will only become invalid through explicit removal from the TLSA RRset (presumably after it is augmented by an RR matching a new certificate which then replaces the original). This simplified authentication protocol for SMTP is carefully designed to avoid most operational pitfalls, and the hope is that it will be reliable enough to be enabled by default on clients and stable when deployed with care on servers. All that aside, the main point is that there is NO conflict between "pre-DANE" opportunistic TLS and DANE opportunistic TLS. The latter is turned on only at the request of the server operator. As to why MTA to MTA SMTP is more special in this regard than HTTPS, the main reason is that MTAs don't generally roam into hotels, internet cafes, and other DNSSEC hostile environments. Being server infrastructure MTAs are much less likely to run into MITM false positives due to shifting network conditions. -- Viktor.
- [dane] Lukewarm discussion: DANE for opportunisti… Viktor Dukhovni
- Re: [dane] Lukewarm discussion: DANE for opportun… James Cloos
- Re: [dane] Lukewarm discussion: DANE for opportun… Peter Saint-Andre
- Re: [dane] Lukewarm discussion: DANE for opportun… Paul Hoffman
- Re: [dane] Lukewarm discussion: DANE for opportun… Viktor Dukhovni
- Re: [dane] Lukewarm discussion: DANE for opportun… James Cloos
- Re: [dane] Lukewarm discussion: DANE for opportun… Warren Kumari
- Re: [dane] Lukewarm discussion: DANE for opportun… Viktor Dukhovni
- Re: [dane] Lukewarm discussion: DANE for opportun… Viktor Dukhovni
- Re: [dane] Lukewarm discussion: DANE for opportun… Phillip Hallam-Baker
- Re: [dane] Lukewarm discussion: DANE for opportun… Jelte Jansen
- Re: [dane] Lukewarm discussion: DANE for opportun… Nicholas Weaver
- Re: [dane] Lukewarm discussion: DANE for opportun… Paul Wouters
- Re: [dane] Lukewarm discussion: DANE for opportun… Nicholas Weaver
- Re: [dane] Lukewarm discussion: DANE for opportun… Viktor Dukhovni