Re: [TLS] DNS-based Encrypted SNI
Ben Schwartz <bemasc@google.com> Tue, 03 July 2018 15:21 UTC
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From: Ben Schwartz <bemasc@google.com>
Date: Tue, 03 Jul 2018 11:20:22 -0400
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To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] DNS-based Encrypted SNI
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On Mon, Jul 2, 2018 at 7:41 PM Eric Rescorla <ekr@rtfm.com> wrote: > Hi folks, > > I just submitted: > > https://tools.ietf.org/html/draft-rescorla-tls-esni-00 > > This draft describes a DNS-based approach to doing encrypted SNI. > Thanks for this proposal, Eric. I fully support this line of work. This proposal obviously bears some relevance to the SNI Alt-Svc + DNS ALTSVC drafts in HTTPBIS [1][2]. That's OK; we'll sort it out eventually. I hope people interested in this draft will also check out those. In my view, ESNI and those drafts are two complementary approaches to this problem. I can see reasons to pick one, or both, or a combination. [1] https://tools.ietf.org/html/draft-bishop-httpbis-sni-altsvc-02 [2] https://tools.ietf.org/html/draft-schwartz-httpbis-dns-alt-svc-02 On Mon, Jul 2, 2018 at 11:59 PM Eric Rescorla <ekr@rtfm.com> wrote: > On Mon, Jul 2, 2018 at 8:53 PM, Paul Wouters <paul@nohats.ca> wrote: > ... > It is strongly recommended not to use TXT records. Why not use a new >> RRTYPE? Everything these days knows how to serve unknown record types >> (see RFC 3597). The only possibly exception is provisioning tools of >> small players, but this document starts of saying you basically need >> to be on a bulk hosting provider anyway. They can properly provision. >> > > See: > > https://github.com/ekr/draft-rescorla-tls-esni/issues/7#issuecomment-388531906 > <https://github..com/ekr/draft-rescorla-tls-esni/issues/7#issuecomment-388531906> > That logic (CNAME compatibility) requires not placing this information at the apex, i.e. using a prefix, as you've done. It doesn't preclude using a new record type. The DNS ALTSVC draft, for example, does both. Some other thoughts: I expect much nitpicking of the exact DNS syntax. You may end up wanting to describe that separately, especially since these "introduction tokens" may well be useful to acquire over non-DNS channels (e.g. Alt-Svc) and may be useful for non-SNI purposes (like 0-RTT, as you've noted). I wonder how well this scales to a "large key" future (e.g. post-quantum). As described, this approach seems hard to use with a domain load-balanced across two CDNs. (I don't know how important that use case is.) One concern I've heard many times is that we can't add non-A/AAAA queries to a browser's critical path because there are middleboxes and buggy recursives that will just drop them, leading to a DNS timeout delay on every new socket. However, for encrypted SNI I think we can ignore this by focusing on clients with DPRIVE or DOH enabled, which should avoid these kinds of problems.
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Short, Todd
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Brian Sniffen
- Re: [TLS] DNS-based Encrypted SNI Short, Todd
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Paul Wouters
- Re: [TLS] DNS-based Encrypted SNI Sniffen, Brian
- Re: [TLS] DNS-based Encrypted SNI Ben Schwartz
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Paul Wouters
- Re: [TLS] DNS-based Encrypted SNI Patrick McManus
- Re: [TLS] DNS-based Encrypted SNI Tim Hollebeek
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Kazuho Oku
- Re: [TLS] DNS-based Encrypted SNI Ilari Liusvaara
- Re: [TLS] DNS-based Encrypted SNI Ilari Liusvaara
- Re: [TLS] DNS-based Encrypted SNI Ilari Liusvaara
- Re: [TLS] DNS-based Encrypted SNI Stephen Farrell
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Eric Rescorla
- Re: [TLS] DNS-based Encrypted SNI Kathleen Moriarty
- Re: [TLS] DNS-based Encrypted SNI Stephen Farrell
- Re: [TLS] DNS-based Encrypted SNI Kathleen Moriarty
- Re: [TLS] DNS-based Encrypted SNI Kazuho Oku