> -----Original Message-----
> From: Narayanan, Vidya [mailto:[EMAIL PROTECTED] 
> Sent: Tuesday, March 06, 2007 11:51 AM
> To: Bernard Aboba; [email protected]
> Subject: RE: [Emu] RFC4279 support in draft-simon-emu-rfc2716bis?
> 
> Hi Bernard,
> Thanks much for the response. If we go down this path, are we 
> then saying that for every new ciphersuite that may be added 
> to TLS, a separate EAP method would need to be designed to 
> support that in EAP?
> Also, how is this different from TLS implementations having 
> to support the newer ciphersuites? 
> 

[Joe] We have a charter item for enhanced TLS which could support other
types of ciphersuites along with other features. 

> I can understand the mandatory cert requirement in RFC2716, 
> since at that point of time, TLS did not have the PSK 
> ciphersuites. But, now that we are revising it, does it not 
> make sense to support all the ciphersuites supported in TLS? 
> 
> Also, could you please elaborate on the multiple negotiation problem?
> Looking at the message flows in section 2.1 in
> draft-otto-emu-eap-tls-psk-02 and section 2.1.1 in 
> draft-simon-emu-rfc2716bis-08, except for the certs portion, 
> everything else looks the same. 
> 

[Joe] EAP negotiation happens early before TLS negotiation.  If a peer
or server negotiate a particular EAP method they may actually not
actually be able to complete this because TLS negotiation arrives upon
an result that is not satisfactory. Restricting EAP-TLS to certificate
based ciphers does not solve this problem, but it helps. In an enhanced
EAP-TLS the initial message from the server could indicate the supported
ciphers giving the chance for a client to NAK. 


> Thanks,
> Vidya
> 
> > -----Original Message-----
> > From: Bernard Aboba [mailto:[EMAIL PROTECTED]
> > Sent: Monday, March 05, 2007 11:29 PM
> > To: Narayanan, Vidya; [email protected]
> > Subject: RE: [Emu] RFC4279 support in draft-simon-emu-rfc2716bis?
> > 
> > According to RFC 2716, a compliant EAP-TLS implementation 
> must support 
> > certificates.  Since the resources required to support 
> certificates is 
> > much larger than the resources required for TLS-PSK, a 
> combined method 
> > would not be optimal for use within an embedded environment.  There 
> > would also be substantial costs to adding support for additional 
> > authentication methods to EAP-TLS.  For example, EAP-TLS 
> certification 
> > and testing programs have been developed which focus solely on 
> > certificate ciphersuites; rewriting those test suites would 
> be costly.
> > 
> > By developing EAP-TLS-PSK as a separate EAP method an 
> implementation 
> > can solely implement TLS-PSK while remaining compliant.  
> This permits 
> > EAP TLS-PSK implementations to be optimized for embedded 
> environments.  
> > As a side benefit, this approach also eliminates multiple levels of 
> > negotiation, which had been raised as a potential problem.
> > 
> > 
> > 
> 
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