Subject: Comment on AttributeCertificate draft

From: [email-masked]
Date: Sat, 2 Sep 2000 22:31:03 -0700

Stephen,

How does this proposal fit (or not) with the theoretical work on SPKI (RFC
2693)?
In particular, an AC does not have a public key AND a single PKC may have
multiple ACs. Also, SPKI suggestion on the use of X9.57 to specify authorization
attributes in X.509v3.

Regards,
Ron.

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From: Stephen Farrell <[email-masked]>
Date: Mon, 04 Sep 2000 11:08:59 +0100

Hi Ron,

I'd have to say that the AC work doesn't have any direct "fit" 
with SPKI since its just a profile of X.509 ACs. Having said that
however, a combination of X.509 ACs and PKCs can be used to
achieve the same authorization functionality as SPKI, though
you'd still have anti-ASN.1 reasons to use SPKI if you believe
in those. So basically its another way to do the same thing,
but based on X.509 and not 5-tuples.

I'm not familiar with X9.57, so I can't comment on it.

Regards,
Stephen.

-- 
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Stephen Farrell         				   
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From: "Carl Ellison" <[email-masked]>
Date: 4 Sep 2000 11:44:27 -0700

>I'm not familiar with X9.57, so I can't comment on it.

Hi Stephen,

we should probably sit down for a few hours and go over these details.

My standard triangle diagram of certificates includes

attribute (authorization to name)
ID (name to key)
and
authorization (authorization to key)

It is true that you can achieve the authorization mapping by a combination 
of and attribute and ID.

Aside from ASN.1 vs. S-expression religion, there are some things we did in 
SPKI that X.509 is slow in dealing with.  Most especially here I see a 
lingering temptation in the X.509 community to retain the original X.500 
notion that a DN is an identifier.  In SPKI we knew up front that names were 
local, but that an attribute instrument (whether ACL or attribute 
certificate) needed a global name, so we defined a global name as:

(name <key> <name-spelling>)

where <key> is the public key (or its hash) of the CA and <name-spelling> is 
the text of the name (DN in your case).

For a little more on this topic, see http://world.std.com/~cme/html/web.html

==========

X9.57 is an ANSI standard that defines a key-style ACL.  That is, it defines 
authorization entries in a protected database -- with each entry mapping 
(authorization to key).  This is for the banking system, and the 
authorization is usually access to a particular bank account.  It has the 
advantage that it is more secure than any system using certificates but 
because it uses no certificates, it is less expensive and complex.  It has 
limitations in delegation, but for the purpose it was designed for, it is a 
good solution.

 - Carl

+------------------------------------------------------------------+
|Carl M. Ellison         [email-masked]     http://world.std.com/~cme |
|    PGP: 08FF BA05 599B 49D2  23C6 6FFD 36BA D342                 |
+--Officer, officer, arrest that man. He's whistling a dirty song.-+

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From: "Carl Ellison" <[email-masked]>
Date: 4 Sep 2000 11:47:35 -0700

>It is true that you can achieve the authorization mapping by a combination 
    ^^^

drop that word