Re: [TLS] Data volume limits
Watson Ladd <watsonbladd@gmail.com> Tue, 15 December 2015 23:47 UTC
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Date: Tue, 15 Dec 2015 18:47:57 -0500
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From: Watson Ladd <watsonbladd@gmail.com>
To: "Scott Fluhrer (sfluhrer)" <sfluhrer@cisco.com>
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Subject: Re: [TLS] Data volume limits
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On Dec 15, 2015 6:08 PM, "Scott Fluhrer (sfluhrer)" <sfluhrer@cisco.com> wrote: > > > > > -----Original Message----- > > From: Watson Ladd [mailto:watsonbladd@gmail.com] > > Sent: Tuesday, December 15, 2015 5:38 PM > > To: Scott Fluhrer (sfluhrer) > > Cc: Eric Rescorla; tls@ietf.org > > Subject: Re: [TLS] Data volume limits > > > > On Tue, Dec 15, 2015 at 5:01 PM, Scott Fluhrer (sfluhrer) > > <sfluhrer@cisco.com> wrote: > > > Might I enquire about the cryptographical reason behind such a limit? > > > > > > > > > > > > Is this the limit on the size of a single record? GCM does have a > > > limit approximately there on the size of a single plaintext it can > > > encrypt. For TLS, it encrypts a record as a single plaintext, and so > > > this would apply to extremely huge records. > > > > The issue is the bounds in Iwata-Ohashai-Minematsu's paper, which show a > > quadratic confidentiality loss after a total volume sent. This is an exploitable > > issue. > > Actually, the main result of that paper was that GCM with nonces other than 96 bits were less secure than previous thought (or, rather, that the previous proofs were wrong, and what they can prove is considerably worse; whether their proof is tight is an open question). They address 96 bit nonces as well, however the results they get are effectively unchanged from the original GCM paper. I had thought that TLS used 96 bit nonces (constructed from 32 bit salt and a 64 bit counter); were the security guarantees from the original paper too weak? If not, what has changed? > > The quadratic behavior in the security proofs are there for just about any block cipher mode, and is the reason why you want to stay well below the birthday bound. However, that's as true for (say) CBC mode as it is for GCM That's correct. And when we crunch the numbers assuming 2^60 is negligible out comes 2^36 bytes. This doesn't hold for ChaCha20. >
- Re: [TLS] Data volume limits Watson Ladd
- [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Dave Garrett
- Re: [TLS] Data volume limits Benjamin Beurdouche
- Re: [TLS] Data volume limits Scott Fluhrer (sfluhrer)
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Russ Housley
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Hanno Böck
- Re: [TLS] Data volume limits Scott Fluhrer (sfluhrer)
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Brian Smith
- Re: [TLS] Data volume limits Henrick Hellström
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Andrey Jivsov
- Re: [TLS] Data volume limits Scott Fluhrer (sfluhrer)
- Re: [TLS] Data volume limits Henrick Hellström
- Re: [TLS] Data volume limits Brian Smith
- Re: [TLS] Data volume limits Martin Thomson
- Re: [TLS] Data volume limits Martin Thomson
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Dave Garrett
- Re: [TLS] Data volume limits Stephen Farrell
- Re: [TLS] Data volume limits Dave Garrett
- Re: [TLS] Data volume limits Martin Thomson
- Re: [TLS] Data volume limits Bill Frantz
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Martin Thomson
- Re: [TLS] Data volume limits Dave Garrett
- Re: [TLS] Data volume limits Andrey Jivsov
- Re: [TLS] Data volume limits Ryan Carboni
- Re: [TLS] Data volume limits Paterson, Kenny
- Re: [TLS] Data volume limits Simon Josefsson
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Henrick Hellström
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Dang, Quynh
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Brian Smith
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Brian Smith
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Nikos Mavrogiannopoulos
- Re: [TLS] Data volume limits Yoav Nir
- Re: [TLS] Data volume limits Dang, Quynh
- Re: [TLS] Data volume limits Hubert Kario
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Florian Weimer
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Florian Weimer
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Ilari Liusvaara
- Re: [TLS] Data volume limits Salz, Rich
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Dang, Quynh
- Re: [TLS] Data volume limits Brian Smith
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Dave Garrett
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Blumenthal, Uri - 0553 - MITLL
- Re: [TLS] Data volume limits Aaron Zauner
- Re: [TLS] Data volume limits Aaron Zauner
- Re: [TLS] Data volume limits Ilari Liusvaara
- Re: [TLS] Data volume limits Samuel Neves
- Re: [TLS] Data volume limits Henrick Wibell Hellström
- Re: [TLS] Data volume limits Ilari Liusvaara
- Re: [TLS] Data volume limits Aaron Zauner
- Re: [TLS] Data volume limits sneves
- Re: [TLS] Data volume limits Aaron Zauner
- Re: [TLS] Data volume limits James Cloos
- Re: [TLS] Data volume limits Samuel Neves
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits Ilari Liusvaara
- Re: [TLS] Data volume limits James Cloos
- Re: [TLS] Data volume limits Watson Ladd
- Re: [TLS] Data volume limits Eric Rescorla
- Re: [TLS] Data volume limits James Cloos
- Re: [TLS] Data volume limits Hubert Kario
- Re: [TLS] Data volume limits Florian Weimer
- Re: [TLS] Data volume limits Florian Weimer
- Re: [TLS] Data volume limits Hubert Kario
- Re: [TLS] Data volume limits Florian Weimer
- Re: [TLS] Data volume limits Benjamin Kaduk
- Re: [TLS] Data volume limits Florian Weimer