Re: [Emu] I-D Action:draft-ietf-emu-eap-gpsk-09.txt

[Hannes Tschofenig <[e-mail]>]

Hi Dan,

Dan Harkins wrote:
>   Hi,
>
>   I just glanced over this draft. In section 12.1 each of the security
> claims seems to refer to sections from the -08 version of the draft.
> For instance,
>
>        Confidentiality:           No (section 11.14 and 11.16)
>
> where in the -08 draft sections 11.14 and 11.16 discuss ID protection
> and confidentiality, respectively, but it's 12.15 and 12.17 in the -09
> version. Am I misreading this somehow?
>
>   
You are right. We should have used <xref target=".."/> in the XML text 
rather than hardcoding it. The structure changed but we forgot to update 
this text.

>   I also think that the security claims in 12.1 should explicitly spell
> out whether they meet RFC 4017 requirements, like the charter says.
>
>   I'm glad that my comment on non-resistance to dictionary attack
> was accepted. Thanks! But I still think that section is somewhat
> ambiguous. It says, "Users who use passwords as the basis of their PSK
> are not protected against dictionary attacks." Well, that's true but users
> who do not use passwords as the basis of their PSK are also not protected
> against dictionary attacks!
>
>   I'd like to suggest the following text for section 12.7:
>
>       The success of a dictionary attack against EAP-GPSK depends on
>       the strength of the long-term shared secret (PSK) it uses. The
>       PSK used by EAP-GPSK SHOULD be drawn from a pool of secrets that
>       is at least 2^128 bits large and whose distribution is uniformly
>       random. Note that this does not imply resistance to dictionary
>       attack, only that the probability of success in such an attack
>       is acceptably remote.
>
> That is, I believe, fair, accurate, and unambiguous.
>
>   

Aren't we saying essentially the same in the previous sentences?

------------------------------------------------------------------------------------------------

12.7.  Dictionary Attacks

   EAP-GPSK relies on a long-term shared secret (PSK) that SHOULD be
   based on at least 16 octets of entropy to be fully secure.  The EAP-
   GPSK protocol makes no special provisions to ensure keys based on
   passwords are used securely.  Users who use passwords as the basis of
   their PSK are not protected against dictionary attacks.  Derivation
   of the long-term shared secret from a password is strongly
   discouraged.

------------------------------------------------------------------------

If you think we haven't discouraged folks enough to use passwords 
with the current text then we could add your text in addition to it. 



Ciao
Hannes

>   regards,
>
>   Dan.
>
> On Fri, June 27, 2008 8:30 am, [e-mail] wrote:
>   
>> A New Internet-Draft is available from the on-line Internet-Drafts
>> directories.
>> This draft is a work item of the EAP Method Update Working Group of the
>> IETF.
>>
>>
>> 	Title           : EAP Generalized Pre-Shared Key (EAP-GPSK) Method
>> 	Author(s)       : C. Clancy, H. Tschofenig
>> 	Filename        : draft-ietf-emu-eap-gpsk-09.txt
>> 	Pages           : 38
>> 	Date            : 2008-06-27
>>
>> This Internet Draft defines an Extensible Authentication Protocol
>> method called EAP Generalized Pre-Shared Key (EAP-GPSK).  This method
>> is a lightweight shared-key authentication protocol supporting mutual
>> authentication and key derivation.
>>
>> A URL for this Internet-Draft is:
>> http://www.ietf.org/internet-drafts/draft-ietf-emu-eap-gpsk-09.txt
>>
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>
>> Below is the data which will enable a MIME compliant mail reader
>> implementation to automatically retrieve the ASCII version of the
>> Internet-Draft.
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>>
>>     
>
>
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