Re: [TLS] Some comments about draft-badra-ecdhe-tls-psk-01

[Mohamad Badra <badra@xxxxxxxx>]

Dear Pasi,

> Overall comment: While the technical solution is reasonably defined 
> and scoped, do we have any evidence that someone cares about it?
> I.e., do we have information suggesting that if this was specified,
> it would actually be used in real world? If we don't, let's not 
> spend WG time on it...

A few of volunteers already reviewed the document. As you said early, 
the technical solution is reasonably defined and scoped and therefore I 
don't think that we need enough time to spend on it. The evidence that 
someone cares about it depends on the TLS-PSK itself: why someone care 
on RSA_PSK and DH_PSK but not on ECDHE_PSK? However, I do support any 
opinion poll on that through asking that someone: Do you support 
adopting that document?


> Some additional comments based on a quick read:
>
> Abstract, "This document updates RFC 4785 and 4279..."; it 
> doesn't "update" either of them (in the sense the word "update" 
> is usually used when talking about relationships between RFCs);
> it just defines additional cipher suites.

OK, I will replace "update" with "extend".


> Section 2, "First, perform the Elliptic Curve Diffie-Hellman
> computation in the same way as for other Diffie-Hellman-based
> ciphersuites in [TLS1.0] or [TLS1.1]" Neither document contains
> information on how to perform ECDH computations.

This is a mistake, I will replace "[TLS1.0] or [TLS1.1]" with "RFC4492".


> Section 2, "Let Z be the value produced by this computation",
> Elliptic Curve Diffie-Hellman is somewhat different in this
> respect; text should be consistent with RFC 4492 Section 5.10.

What about replacing:

   The premaster secret is formed as follows. First, perform the
   Elliptic Curve Diffie-Hellman computation in the same way as for
   other Diffie-Hellman-based ciphersuites in [TLS1.0] or [TLS1.1]. Let
   Z be the value produced by this computation. Concatenate a uint16
   containing the length of Z (in octets), Z itself, a uint16
   containing the length of the PSK (in octets), and the PSK itself.

With:

   The premaster secret is formed as follows. First, perform the
   Elliptic Curve Diffie-Hellman computation in the same way as for
   other Diffie-Hellman-based ciphersuites defined in RFC4492 to
   generate the octet string [RFC4492]. Next, concatenate a uint16
   containing the length of the octet string (in octets), the octet
   strinf itself, a uint16 containing the length of the PSK (in octets),
   and the PSK itself.

> Typos/grammar:
> "These ciphersuites provides.."
> "It specifies as well one.."

OK.

> > From idnits: Unused Reference: 'RFC2119' is defined on line 160, 
> but no explicit reference was found in the text

OK.

> Best regards,
> Pasi 

Many thanks!
Best regards,
--
Mohamad Badra
CNRS - LIMOS Laboratory



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