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Re: SPKI signing keys only



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At 09:14 AM 6/23/97 -0400, David P. Kemp wrote:
>Others have found a need to make the distinction between signing keys
>and key establishment keys.  If SPKI chooses not to make the distinction,
>it will just be deferring the decision to private agreement among
>implementors.  One way of being "simple" is to avoid standardizing
>such usage conventions.  I question the wisdom of that, but since there
>is already a PKI architecture that does provide a framework for
>standardizing the meaning of various "auths", it is probably good for
>SPKI to *not* standardize them, and instead defer the definition of
>"auth" meanings to bilateral agreements and community usage profiles.

I follow the argument and there's certainly room in an authorization field 
to say "this is an encryption key".  However, I have been led by recent 
examples from elsewhere to assume that we should define a key-use field 
inside the key block itself -- so that even if we had the same RSA modulus 
and exponent used both for signing and for key transport, the

(public-key ...) 

block would be different for the two and therefore the key hash would 
be different.

 - Carl

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|Carl M. Ellison  cme@cybercash.com   http://www.clark.net/pub/cme |
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