Re: [TLS] Comments/Questions on draft-gutmann-tls-encrypt-then-mac-00.txt
"Christian Kahlo" <christian.kahlo@ageto.net> Mon, 23 September 2013 12:50 UTC
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From: Christian Kahlo <christian.kahlo@ageto.net>
To: 'Nikos Mavrogiannopoulos' <nmav@gnutls.org>, tls@ietf.org
References: <CABcZeBN+0hX1-cb0V4AyaO3FrwaGrtjbRO3BGOV0KBSjRkNwkw@mail.gmail.com> <523c738f.0733cc0a.41a0.3096@mx.google.com> <523F383A.20803@drh-consultancy.co.uk> <523FE7B6.10501@gnutls.org>
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Date: Mon, 23 Sep 2013 14:50:07 +0200
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Cc: 'Team Neuer Personalausweis' <npa@ageto.net>
Subject: Re: [TLS] Comments/Questions on draft-gutmann-tls-encrypt-then-mac-00.txt
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Nikos, > > This has some interesting parallels with FIPS 140-2. Currently the > only approved > > symmetric algorithms for FIPS 140-2 and TLS are AES-GCM, AES-CBC and > DES3-CBC. > > If you can't deploy TLS 1.2 you're then stuck with CBC. > [...] > > spec, as it doesn't need any new algorithms, could be > > deployed as soon as it is approved. > > > > I'm not saying that we don't approve new algorithms and ciphers > suites. I'm > > saying we need ETM as well. > > What we need is a solution for the issue with the unauthenticated > padding in the CBC ciphersuites. ETM is not the only way to solve the > issue, and even if it is used, it would be highly recommendable to > follow the existing good practices. TLS isn't the first protocol to use > this mode, thus there isn't a need to innovate. maybe you want to read http://cseweb.ucsd.edu/~mihir/papers/oem.pdf and http://www.iacr.org/archive/crypto2001/21390309.pdf. Both mentioned within this thread: http://crypto.stackexchange.com/questions/202/should-we-mac-then-encrypt-or- encrypt-then-mac Please tell us which protocols are still using Mac-then-Encrypt today without running into any security trouble (esp. chosen ciphertext attacks). MtE is considered as a design fail by many researchers. As we discussed earlier AEAD might be a solution, but AEAD is not the only one. I would encourage everbody to also have a look into ISO7816-4 secure messaging. That's the way most electronic ID cards, electronic purse cards, credit cards, small HSMs, etc. do communicate. And now think about that there's a reason for that it's an EtM- scheme. Sorry, your attitude "there isn't a need to innovate" sounds somewhat unfamiliar with cryptographic primitives to me. Cheers, Christian
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- [TLS] Comments/Questions on draft-gutmann-tls-enc… Eric Rescorla
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Christian Kahlo
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Dr Stephen Henson
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bill Frantz
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Nikos Mavrogiannopoulos
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Nikos Mavrogiannopoulos
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Christian Kahlo
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Nikos Mavrogiannopoulos
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Christian Kahlo
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Eric Rescorla
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Alfredo Pironti
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Ralph Holz
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Adam Langley
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Michael D'Errico
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Yaron Sheffer
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Michael D'Errico
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Yaron Sheffer
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Martin Rex
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Mohamad Badra
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Martin Rex
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Michael D'Errico
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Martin Rex
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Martin Rex
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Peter Gutmann
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Paul Bakker
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Paul Bakker
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Alfredo Pironti
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Paul Bakker
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Bodo Moeller
- Re: [TLS] Comments/Questions on draft-gutmann-tls… Yoav Nir