Re: [TLS] Wrapping up cached info
Marsh Ray <marsh@extendedsubset.com> Mon, 17 May 2010 17:03 UTC
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Date: Mon, 17 May 2010 12:02:55 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: "Joseph Salowey (jsalowey)" <jsalowey@cisco.com>
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Cc: tls@ietf.org
Subject: Re: [TLS] Wrapping up cached info
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On 5/17/2010 11:29 AM, Joseph Salowey (jsalowey) wrote: > I agree with Uri, that if you determine you need SHA-256 then you should > plan for hash agility. TLS 1.2 plans for hash agility. > > What about Nico's proposal where a checksum is used to identify the > cached data and the actual handshake contains the actual data hashed > with the algorithm used in the PRF negotiated with the cipher suite? > > This way we don't have to introduce hash agility into the extension, but > we have cryptographic hash agility where it matters in the Finished > computation. Does it solve the problem? It could perhaps be made to solve the problem, but IMHO it would require so much additional complexity (aka attack surface) that it wouldn't be worth it. While I don't like to reject anything out-of-hand, injecting data into the calculation of the Finished messages raises a lot of concerns. The way it currently works (the data interpreted logically is just the bytes as seen in the hanshake records) has a certain elegant simplicity that would be a shame to lose. The consequence of the loss of integrity in the calculation of the Finished messages is pretty much a complete compromise of the security. For example, how will the injected data be wrapped? (It must be delimited somehow or ambiguities may be possible). If they are replaced as in-line substitutions will lengths of enclosing objects be fixed up? If there are multiple substitutions, in what order will the replacements be injected? For an attacker who can efficiently create checksum collisions does it make any precomputed attacks easier? Will this require changes in any commonly used APIs (PKCS#11, Schannel, etc)? - Marsh
- Re: [TLS] Wrapping up cached info Blumenthal, Uri - 0668 - MITLL
- [TLS] Consensus Call: FNV vs SHA1 Joseph Salowey (jsalowey)
- Re: [TLS] Consensus Call: FNV vs SHA1 Simon Josefsson
- Re: [TLS] Consensus Call: FNV vs SHA1 Blumenthal, Uri - 0668 - MITLL
- Re: [TLS] Consensus Call: FNV vs SHA1 Adam Langley
- Re: [TLS] Consensus Call: FNV vs SHA1 Marsh Ray
- Re: [TLS] Consensus Call: FNV vs SHA1 Robert Dugal
- Re: [TLS] Consensus Call: FNV vs SHA1 Stefan Santesson
- Re: [TLS] Consensus Call: FNV vs SHA1 Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Stefan Santesson
- Re: [TLS] Consensus Call: FNV vs SHA1 Martin Rex
- Re: [TLS] Consensus Call: FNV vs SHA1 Jeffrey A. Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Paul Hoffman
- [TLS] Collisions (Re: Consensus Call: FNV vs SHA1) Nicolas Williams
- [TLS] Nico's suggestions - Re: Consensus Call: FN… Stefan Santesson
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Blumenthal, Uri - 0668 - MITLL
- [TLS] Collisions (Re: Nico's suggestions - Re: Co… Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Simon Josefsson
- [TLS] Collisions (Re: Consensus Call: FNV vs SHA1) Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Simon Josefsson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Stefan Santesson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Consensus Call: FNV vs SHA1 Hovav Shacham
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Simon Josefsson
- Re: [TLS] Consensus Call: FNV vs SHA1 Yoav Nir
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Martin Rex
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Consensus Call: FNV vs SHA1 Simon Josefsson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Michael D'Errico
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Martin Rex
- Re: [TLS] Consensus Call: FNV vs SHA1 Kemp, David P.
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Nicolas Williams
- Re: [TLS] Consensus Call: FNV vs SHA1 Blumenthal, Uri - 0668 - MITLL
- Re: [TLS] Consensus Call: FNV vs SHA1 Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Martin Rex
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Kemp, David P.
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Kemp, David P.
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Marsh Ray
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Nicolas Williams
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- Re: [TLS] [POSSIBLE SPAM] Re: Collisions (Re: Nic… Kemp, David P.
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Nicolas Williams
- Re: [TLS] [POSSIBLE SPAM] Re: Collisions (Re: Nic… Marsh Ray
- Re: [TLS] [POSSIBLE SPAM] Re: Collisions (Re: Con… Kemp, David P.
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Stefan Santesson
- Re: [TLS] [POSSIBLE SPAM] Re: Collisions (Re: Con… Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Marsh Ray
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Stefan Santesson
- Re: [TLS] Collisions (Re: Consensus Call: FNV vs … Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Simon Josefsson
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Brian Smith
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Simon Josefsson
- Re: [TLS] Justification Adam Langley
- Re: [TLS] Justification Brian Smith
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Adam Langley
- Re: [TLS] Justification Marsh Ray
- Re: [TLS] Justification Brian Smith
- Re: [TLS] [POSSIBLE SPAM] Re: Collisions (Re: Con… Kemp, David P.
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Adam Langley
- [TLS] Use HTTP (Re: Justification) Nicolas Williams
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Justification Yoav Nir
- Re: [TLS] Justification Michael D'Errico
- Re: [TLS] Justification Martin Rex
- Re: [TLS] Justification Marsh Ray
- Re: [TLS] Justification Stefan Santesson
- Re: [TLS] Justification Martin Rex
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Yoav Nir
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Stefan Santesson
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Collisions (Re: Nico's suggestions - Re… Marsh Ray
- Re: [TLS] Justification Dean Anderson
- [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Simon Josefsson
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Justification Stefan Santesson
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Justification Nicolas Williams
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Joseph Salowey (jsalowey)
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Ben Laurie
- Re: [TLS] Wrapping up cached info Yoav Nir
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Ben Laurie
- Re: [TLS] Wrapping up cached info Martin Rex
- [TLS] Possible alternative to current cached info… Michael D'Errico
- Re: [TLS] Wrapping up cached info (and PRF WTF) Kemp, David P.
- Re: [TLS] Wrapping up cached info (and PRF WTF) Martin Rex
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info (and PRF WTF) Nicolas Williams
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Joseph Salowey (jsalowey)
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Michael D'Errico
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Joseph Salowey (jsalowey)
- Re: [TLS] Wrapping up cached info Joseph Salowey (jsalowey)
- Re: [TLS] Wrapping up cached info Marsh Ray
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Michael D'Errico
- Re: [TLS] Wrapping up cached info Michael D'Errico
- Re: [TLS] Wrapping up cached info Kemp, David P.
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Ben Laurie
- Re: [TLS] Wrapping up cached info Brian Smith
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Martin Rex
- Re: [TLS] Wrapping up cached info Brian Smith
- Re: [TLS] Wrapping up cached info Nicolas Williams
- Re: [TLS] Wrapping up cached info Stefan Santesson
- Re: [TLS] Wrapping up cached info Brian Smith
- Re: [TLS] Wrapping up cached info Brian Smith
- Re: [TLS] Wrapping up cached info Nicolas Williams