cryptoIDs

Trevor Perrin trevp at trevp.net
Thu Oct 16 14:58:06 EDT 2003


At 09:51 AM 10/16/2003 -0500, Von Welch wrote:

>Trevor Perrin writes (02:53 October 16, 2003):
>...
>  > Anyways, for private-key management people should use certs - store your
>  > root key (i.e. the key that matches the fingerprint) in a safe place (for
>  > most people, this would be with their employer or a commercial 
> service; but
>  > the security-conscious can do whatever they want).  Then have your 
> root-key
>  > issue you short-lived certs for use on your cell-phone, email client, web
>  > browser, etc..
>
>In the Grid community these short-lived certs you mention exist and
>are in day-to-day use for the sort of delegation you describe. We call
>them proxy certificates and have standardized them through the IETF
>PKIX working group. See the following url for the latest draft (which
>has passed WG last call).
>
>http://www.ietf.org/internet-drafts/draft-ietf-pkix-proxy-08.txt
>
>A service implementation also exists to hand out Proxy Certificates
>from the long-term credentials as you suggest. It's called MyProxy,
>and you can find more information at http://myproxy.ncsa.uiuc.edu

Hi Von,

yes, I like those, and I discuss them - 
http://trevp.net/cryptoID/cryptoID.html#3.2.1

PGP subkeys and SPKI certs can also be used for "key management" in this 
fashion.  I don't claim this is novel.

I *do* think that if you design a new cert format from scratch, without 
sticking within X.509's straitjacket, you can get something 
better.  CryptoID certs allow threshold subjects (like SPKI), timed and 
one-time revalidation (ditto), they have an authorization language suited 
to the task at hand (saying which protocols a key can be used with), and 
they're a clean, simple XML format.

Of course, they're also not compatible with X.509 software :-(.  If you 
don't like that trade-off, then I agree that proxy certs are the better choice.


Trevor 

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