Re: [TLS] WGLC: draft-ietf-tls-session-hash
Henrik Grubbström <grubba@gmail.com> Fri, 16 January 2015 10:52 UTC
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Date: Fri, 16 Jan 2015 11:52:40 +0100
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From: Henrik Grubbström <grubba@gmail.com>
To: Eric Rescorla <ekr@rtfm.com>
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Cc: Stephen Checkoway <s@pahtak.org>, "TLS@ietf.org (tls@ietf.org)" <tls@ietf.org>
Subject: Re: [TLS] WGLC: draft-ietf-tls-session-hash
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On Fri, Jan 16, 2015 at 12:29 AM, Eric Rescorla <ekr@rtfm.com> wrote: > > On Thu, Jan 15, 2015 at 3:21 PM, Martin Thomson <martin.thomson@gmail.com> > wrote: >> >> On 15 January 2015 at 14:51, Eric Rescorla <ekr@rtfm.com> wrote: >> > For sessions negotiated without EMS: >> > - SHOULD not resume >> > - MUST not resume sessions if the client offers EMS in the resumption >> > (and therefore SHOULD do a complete negotiation). >> > >> > For sessions negotiated with EMS: >> > - The client ??? offer EMS >> > - The server MUST NOT echo it? >> >> Just to be clear, this latter part is...when renegotiating. > > When resuming, right? Maybe something like the following should be added in TLS 1.3? A session MUST only be resumed if the server would create an equivalent session (including the same server certificate and version of TLS) on resumption failure. On resumption failure the session_id provided in the ClientHello MUST be invalidated. Such a rule would ensure that extensions like server_name, max_fragment_length, truncated_hmac, encrypt_then_mac and extended_master_secret (where relevant) are kept in the resumption ClientHello, and that the connection won't be downgraded on resumption failure. >> My preference is: if the session had EMS, when renegotiating: >> - the client MUST offer the extension, and >> - the server MUST fail the handshake (new alert needed?) if the >> extension isn't present. >> >> That means no resumption, OR fallback to the complete handshake. >> >> I think that I'd prefer to have the server echo the extension in this >> case too. It's a few bytes effectively wasted, but it makes >> everything nice and symmetrical. Clients says "I want EMS" and server >> says "you got EMS". Sounds good to me. /grubba -- Henrik Grubbström grubba@grubba.org Roxen Internet Software AB grubba@roxen.com
- [TLS] WGLC: draft-ietf-tls-session-hash Sean Turner
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Stephen Checkoway
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Yoav Nir
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Adam Langley
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Nico Williams
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Stephen Checkoway
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Yoav Nir
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Nico Williams
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Eric Rescorla
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Martin Thomson
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Eric Rescorla
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Martin Thomson
- Re: [TLS] WGLC: draft-ietf-tls-session-hash Henrik Grubbström