Re: Authentication vs. binding signature, and ephemeral vs.permanent key usage

Phillip M Hallam-Baker wrote:
> 
> I don't see any reason for inserting additional text into the
> profile to mandate DS be always set with NR.
 
Well, if some people use NR with and some without the DS bit set there
will be no interoperability because some people/applications will 
assume that a certificate with the DS bit set might be used for 
session-oriented authentication (automated signatures). This will 
impose a high security risk because a NR certificate with the DS bit 
set might than be used for session-oriented authentication applications.

> On the other hand the S/MIME and TLS specifications should be very
> specific about the key usage bits which MUST be set or clear
> for certain operations to be performed.
> 
> In summary this is a very important issue but this is not the place
> to address it. The semantics of the key usage bits will be
> pragmatically defined by applications. 

I thought, that's what the profile is for - specifying or at least
recommending how to use the standardised extensions - to avoid that 
every application has to define it for themselves and therefore to 
achieve interoperability.

Regards - Petra

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