Re: [TLS] draft-green-tls-static-dh-in-tls13-01

Dave Garrett <davemgarrett@gmail.com> Sat, 08 July 2017 22:11 UTC

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From: Dave Garrett <davemgarrett@gmail.com>
To: tls@ietf.org, Matthew Green <matthewdgreen@gmail.com>
Date: Sat, 8 Jul 2017 18:11:41 -0400
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Subject: Re: [TLS] draft-green-tls-static-dh-in-tls13-01
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On Friday, July 07, 2017 03:02:43 am Matthew Green wrote:
> https://tools.ietf.org/html/draft-green-tls-static-dh-in-tls13-01

This document uses the terms:
"Ephemeral (EC)DHE" & "Static (EC)DHE"

The 'E' stands for ephemeral. Regardless of the technical, security, political, logistical, ethical, and whatever merits of this document, could you please make the terminology not hurt my brain? The former is the standard ATM machine silliness, and the later is contradictory and only vaguely viable by fiat of explicitly writing out the silliness:

https://tools.ietf.org/html/draft-green-tls-static-dh-in-tls13-01#section-1.1
>   This document introduces the term "static (elliptic curve) Diffie-
>   Hellman ephemeral", generally written as "static (EC)DHE", to refer
>   to long-lived finite field or elliptic curve Diffie-Hellman keys or
>   key pairs that will be used with the TLS 1.3 ephemeral ciphersuites
>   to negotiate traffic keys for multiple TLS sessions.
>
>   For clarity, this document also introduces the term "ephemeral
>   (elliptic curve) Diffie-Hellman ephemeral", generally written as
>   "ephemeral (EC)DHE", to denote finite field or elliptic curve Diffie-
>   Hellman keys or key pairs that will be used with the TLS 1.3
>   ephemeral ciphersuites to negotiate traffic keys for a single TLS
>   sessions.

It should be simply:
"Ephemeral (EC)DH" & "Static (EC)DH"

Or just:
"(EC)DHE" & "Static (EC)DH"
(or even "(EC)DHS" if you want to use a similar scheme for both)

My argument is that you've got to be able to come up with better terminology than "ephemeral (elliptic curve) Diffie-Hellman ephemeral". Using the same word twice in the same term with slightly different implications is... messy and confusing.


Dave


PS
Response on the merits of the spec to follow in another post.