Subject: RE: Last Call: draft-harkins-emu-eap-pwd (EAP Authentication Using Only APassword) to Informational RFC

From: "Joseph Salowey (jsalowey)" <[email-masked]>
Date: Sun, 9 Aug 2009 22:35:04 -0700

Comments on draft-harkins-emu-eap-pwd-04

1. Prime Modulus groups

In 2.1.1 the document says if the order is unspecified to use  (p-1)/2
and in 2.6.4.2 it says to use (p-1).  It's not really clear which you
mean to use.  In general I don't think you can make specific claims
about the order of the group unless you use specific types of primes or
know the generator you use.  EAP-PWD derives the generator from the
password so it seems that safe primes are assumed (perhaps this should
be stated).  

For section 2.6.3.2 - I think you want r = (p-1)/2 in this case so that
you end up with the pwe as a generator of a prime order sub-group.
Perhaps in section 2.6.4.2, r = (p-1) is necessary, but this is
confusing. 

2. Cipher suites

EAP-pwd would benefit from the ability to negotiate cipher suites.
Currently the server specifies a cipher suite and if the client does not
support it then the exchange fails.  There is no way for the client to
indicate cipher suites it supports.  It seems likely that a server would
support several cipher suite choices while a client would have fewer or
perhaps one.  There is also no indication of which cipher suites are
mandatory to implement. 

3. Support for EAP channel bindings

EAP-pwd does not support the transport of integrity protected data,
which could be used to carry EAP channel bindings.  I think it will
become a requirement for new methods to support EAP channel bindings. 

4. Nits

Section 2.6.5.1 - should probably include reference to UTF-8

Section 2.6.5.3 - in the second paragraph may wait for an EAP-Success as
an alternative to the SHOULD.  EAP-Success is not retransmitted and is
therefore often unreliable.  I don't think this is a good exception to
the SHOULD.  Also in general the EMSK is not exported, but rather keys
derived from the EMSK are exported. 

Joe

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of The IESG
> Sent: Monday, July 13, 2009 2:22 AM
> To: IETF-Announce
> Subject: Last Call: draft-harkins-emu-eap-pwd (EAP 
> Authentication Using Only APassword) to Informational RFC
> 
> The IESG has received a request from an individual submitter 
> to consider the following document:
> 
> - 'EAP Authentication Using Only A Password '
>    <draft-harkins-emu-eap-pwd-04.txt> as an Informational RFC
> 
> The IESG plans to make a decision in the next few weeks, and 
> solicits final comments on this action.  Please send 
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> http://www.ietf.org/internet-drafts/draft-harkins-emu-eap-pwd-04.txt
> 
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