Re: [TLS] IV Generation was: Clarifications and questions: TLS1.3 - Static RSA and AEAD
mrex@sap.com (Martin Rex) Tue, 27 May 2014 21:21 UTC
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To: Michael StJohns <msj@nthpermutation.com>
Date: Tue, 27 May 2014 23:21:25 +0200
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From: mrex@sap.com
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Subject: Re: [TLS] IV Generation was: Clarifications and questions: TLS1.3 - Static RSA and AEAD
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Michael StJohns wrote: > Martin Rex wrote: >> >> I believe you're misinterpreting the concept of the TLS master secret. >> >> The TLS master secret is *NOT* a key. It is more like the entropy pool >> (internal state) of a DBRG (Deterministic Random Bit Generators). > > > Um.... taken one way you could call any key an entropy pool. I think > you're misinterpreting the characteristics of a key. > > So, no. > > Stealing from the definition of "Cryptographic Key" in SP800-57 part 1 > rev 3: > > > A parameter used in conjunction with a cryptographic algorithm that > > determines its operation in such a way that an entity with knowledge of > > the key can reproduce or reverse the operation, while an entity without > > knowledge of the key cannot. > > Continuing, the master secret *is* used explicitly as a MAC key > (finished message) and as a master key for a KDF (key expansion). Unless you're using a NULL encryption ciphersuite, the Finished messages _are_ encrypted, rather than exchanged in the clear, and there is a reason why the Finished message is truncated. For the two communication peers that are involved (TLS client and TLS server), the master secret is a shared secret. For any attacker, the finished messages are not visible (encrypted). > > Seriously though - no. Basically if you share it, it's no longer an > entropy pool, but a key. There is a necessity to share the master secret with your communication peer so that both can derive the same new secrets from it. -Martin
- [TLS] Clarifications and questions: TLS1.3 - Stat… Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Eric Rescorla
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Eric Rescorla
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Alyssa Rowan
- Re: [TLS] Clarifications and questions: TLS1.3 - … Eric Rescorla
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Watson Ladd
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Eric Rescorla
- Re: [TLS] Clarifications and questions: TLS1.3 - … Jakob Breier
- Re: [TLS] Clarifications and questions: TLS1.3 - … Dan Brown
- Re: [TLS] Clarifications and questions: TLS1.3 - … Jakob Breier
- Re: [TLS] Clarifications and questions: TLS1.3 - … Dan Brown
- Re: [TLS] Clarifications and questions: TLS1.3 - … Watson Ladd
- [TLS] IV Generation was: Clarifications and quest… Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Michael StJohns
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Clarifications and questions: TLS1.3 - … Alyssa Rowan
- Re: [TLS] Clarifications and questions: TLS1.3 - … Andy Lutomirski
- Re: [TLS] Clarifications and questions: TLS1.3 - … Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] IV Generation was: Clarifications and q… Martin Rex
- Re: [TLS] IV Generation was: Clarifications and q… Michael StJohns
- Re: [TLS] IV Generation was: Clarifications and q… Martin Rex
- Re: [TLS] IV Generation was: Clarifications and q… Michael StJohns
- Re: [TLS] IV Generation was: Clarifications and q… Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] IV Generation was: Clarifications and q… Michael StJohns