Re: [TLS] History of TLS analysis (was Re: TLS 1.2 Long-term Support Profile draft posted)

Peter Gutmann <pgut001@cs.auckland.ac.nz> Fri, 18 March 2016 23:31 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Watson Ladd <watsonbladd@gmail.com>
Thread-Topic: History of TLS analysis (was Re: [TLS] TLS 1.2 Long-term Support Profile draft posted)
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Date: Fri, 18 Mar 2016 23:31:25 +0000
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Subject: Re: [TLS] History of TLS analysis (was Re: TLS 1.2 Long-term Support Profile draft posted)
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Watson Ladd <watsonbladd@gmail.com>; writes:

>Then use a padding extension that solves all problems, instead of relying on
>a side effect of CBC mode. 

It's not a "side-effect of CBC mode", CBC mode allows padding packets, GCM
doesn't, see Colm MacCárthaigh's recent post on the topic.

>Why do we want this to look different from TLS, instead of a subset of widely
>deployed things ala UTA?

CBC mode ciphers have been part of TLS since SSL 2.0 (AFAIK) in 1994, I don't
know if SSL2 allowed for packet padding but 3.0 certainly did, so it's hardly
a major change.

>What is your master secret change solving?

Preventing manipulation of DH/ECDH parameters.

>Your draft claims that verifying signatures before sending will address an
>ECC security threat. I don't see what threat that addresses

The fact that ECC algorithms are extremely vulnerable to fault attacks, and a
single faulty signature can leak the private key, at which point its game
over.

I don't really know how to say the following without it sounding like an ad
hominem attack, but how much do you really know about real-world deployment
issues for this stuff?  You seem to be arguing for all sorts of personal
preferences based on, I dunno, abstract theorising, but you appear to be
totally unaware of actual real-world issues.  What I'm trying to figure out
is, how seriously am I supposed to take your comments?  Do you actually have
any real-world deployment experience with using this stuff in the field?

Peter.