Re: [TLS] Pull Request: Removing the AEAD explicit IV
Watson Ladd <watsonbladd@gmail.com> Thu, 19 March 2015 17:55 UTC
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Date: Thu, 19 Mar 2015 10:55:54 -0700
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From: Watson Ladd <watsonbladd@gmail.com>
To: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
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Cc: tls@ietf.org
Subject: Re: [TLS] Pull Request: Removing the AEAD explicit IV
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On Mar 19, 2015 10:40 AM, "Ilari Liusvaara" <ilari.liusvaara@elisanet.fi> wrote: > > On Thu, Mar 19, 2015 at 09:20:54AM -0700, Watson Ladd wrote: > > On Thu, Mar 19, 2015 at 4:33 AM, Brian Smith <brian@briansmith.org> wrote: > > > Watson Ladd <watsonbladd@gmail.com> wrote: > > >> If we're going to make a change this > > >> radical, why not make equally radical changes to simplify the protocol > > >> further if that's possible? > > > > > > That's already happening. > > > > No it's not: the draft is still longer than the TLS 1.2 RFC, and seems > > to demand support for every single usecase. This seems at odds with > > absolute simplification, where we would throw out less important > > features, and radically reduce the complexity. > > Got examples of features that could be removed or at least rendered > truly optional (besides things like 0RTT[1])? Update: most connections are short-lived. Changing client auth state during a connection: restarting works fine. The 1 RTT idea being proposed involves remembering unnecessary state. AGL mentioned the ability to have fragmentation of Client Hellos in the record layer. > > > > Also, the proposed changes to the handshake state machine for TLS 1.3 > > > are much larger. It seems we can't substantially simplify the protocol > > > proportionately increasing the complexity of implementations that need > > > to also implement earlier versions. > > > > Adding new states and transitions to a state machine doesn't increase > > complexity that much: if the transition doesn't apply, you don't take > > it. But adding additional special casing all over the place to deal > > with TLS 1.3 does increase complexity much more. > > Unfortunately, to fix the TLS handshaking mechanism, calls for handshake > totally different from one TLS 1.2 has. > > The overall architecture of TLS 1.3 handshake looks good to me, the > divisions it makes look to harden the handshake a lot against various > attacks. Unfortunately, the handshake currently looks to have rather large > implementation security gap. > > Additionally, in practice, the capablity to send a handshake that can > be downnegotiated is needed. This should be doable without increasing the complexity of current code that much. The issue with the handshake isn't so much the parsing ( although nested length encoding is a bad idea, compared to length encoded tokens) but the state machine. Adding new transitions and states carefully shouldn't be too bad. Most implementations already keep a ruuning hash, so the enhanced handshake prorocol can fit in. We should tighten up the description significantly, explaining exactly which steps are expected when. Sincerely, Watson Ladd > > > > [1] If 0RTT was an extension with positive acknowledgement, server could > just leave it unimplemented and things would still work, albeit possibly > with extra RTT. > > > > -Ilari
- [TLS] Pull Request: Removing the AEAD explicit IV Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Adam Langley
- Re: [TLS] Pull Request: Removing the AEAD explici… Michael StJohns
- Re: [TLS] Pull Request: Removing the AEAD explici… Yoav Nir
- Re: [TLS] Pull Request: Removing the AEAD explici… Michael StJohns
- Re: [TLS] Pull Request: Removing the AEAD explici… Michael StJohns
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Watson Ladd
- Re: [TLS] Pull Request: Removing the AEAD explici… Watson Ladd
- Re: [TLS] Pull Request: Removing the AEAD explici… Colm MacCárthaigh
- Re: [TLS] Pull Request: Removing the AEAD explici… Martin Thomson
- Re: [TLS] Pull Request: Removing the AEAD explici… Colm MacCárthaigh
- Re: [TLS] Pull Request: Removing the AEAD explici… Michael StJohns
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Brian Smith
- Re: [TLS] Pull Request: Removing the AEAD explici… Watson Ladd
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Watson Ladd
- Re: [TLS] Pull Request: Removing the AEAD explici… Ilari Liusvaara
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Watson Ladd
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Ilari Liusvaara
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Brian Smith
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Brian Smith
- Re: [TLS] Pull Request: Removing the AEAD explici… Ilari Liusvaara
- Re: [TLS] Pull Request: Removing the AEAD explici… Adam Langley
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Ilari Liusvaara
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Adam Langley
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Brian Smith
- Re: [TLS] Pull Request: Removing the AEAD explici… Eric Rescorla
- Re: [TLS] Pull Request: Removing the AEAD explici… Martin Thomson