Subject: An advice to a commercial CA

From: Joseph Doekbrijder <[email-masked]>
Date: Tue, 02 Dec 2003 09:42:06 +0100

A root key always deserves the lowest level of trust since whatever it 
signs is accepted by the RP.
The clue of the matter is that the RP should not just accept the root, 
but instead the issuing CA as trusted issuing party.
an example

tree / liability
-----/ -----
root / 0
signs  
bronze / 0
signs
silver / 1'000
signs
gold / 10'000
signs
platinum / 100'000
signs
qualified /  1'000'000

with this hierarchy an RP can say "my application (ex: web shop) 
requires silver or better" and thus accept the silver CA. If an RP 
decides to only accept gold level certs (for whatever reason, maybe 
liability) he should never accept the Root key.

This way a CA can decide to provide requesters with a certain level of 
certificate, meant for certain types of transactions (buying a CD vs 
booking hollidays vs or e-voting). And thus fullfill a business case.
The requesters can choose to purchase a cert of a certain quality 
allowing for certain types of transactions independent from the provider 
of these certs.
The RP can look at the cert and base his sell or no-sell decission on 
the cert quality. Also becomming independent of the issuing party.

All this requires, is a verifyable definition of Bronze, Silver, Gold, 
Platinum, Qualified. All issuing parties that are able to offer certs of 
a certain level get "audited" regularly and published to provide 
subscribers and RP's a decission aid. Issuing parties no longer being 
able to offer a certain quality loose their "quality seal" and probably 
their subscribers

regarding the the two different "expensive" issuances.
Here in detail it actually looks like this

signs
silver
signs
silver P(ersonal) and silver S(ervices) and X(xxx)..... and
Gold

Silver, with its sub CA's becomes a level having certain characteristics 
like liability. Thus organisations can choose for a certain level and 
then outsource their entire PKI realizing that registration, liability 
and whatever other elements are important, fit their requirements. This 
is very attractive for an industry that thus becomes independent of CA's 
while determining the minimum requirements of the certs they are willing 
to work with.

RP's actually like this. All they have to decide on is what level of 
certs they are willing to accept. if the cert is of the right level the 
root key of the issuing party no longer matters! trust is based on cert 
quality.

:-)

Looking forward to any feedback

Josh

Anders Rundgren wrote:

>Doesn't your scheme make an RP trusting the "expensive" CA
>also trust the "cheap" CA as they share a common root?
>
>And there could also be just two different "expensive" issuances
>that are incompatible like server-side SSL certs and certs for
>individuals.
>
>It looks to me that you move potential problems to the RP SW.
>Mathematically OK? For sure.  Standards-compliant?  For sure.
>But working?  Under strictly monitored conditions only.  Such
>conditions are unlikely to be met when you start to count RPs
>in the thousands and up.
>
>Anyway. several other folks on the list seem to agree that
>such schemes (including policy OID-enhanced path validation)
>only work in "managed" or "community" based PKIs.
>
>In my opinion the need for standards is much more evident
>in "unmanaged" spaces.
>
>Anders
>
>----- Original Message -----
>From: "Joseph Doekbrijder" <[email-masked]>
>To: "Anders Rundgren" <[email-masked]>
>Cc: "Stephen Kent" <[email-masked]>; <[email-masked]>
>Sent: Thursday, November 27, 2003 10:43
>Subject: Re: Straw poll: An advice to a commercial CA
>
>
>Only logical thing to do is a single root, signing the cheap CA which in
>its turn signs the expensive CA.
>Mathematically correct, includes trust logic, liability levels etc, etc...
>
>This is how we do it. :-)
>
>Cheers
>
>Josh
>
>
>Anders Rundgren wrote:
>
>  
>
>>Well,
>>Since the list is close to "vibrant" with emotions, why not
>>put RFC3280 through the litmus test?
>>
>>Assume that you as PKI professionals would advice a commercial
>>TTP CA on how to configure their issuance for the following:
>>1. Free e-mail roundtrip-verification certficates.  Low insurance level
>>2. Expensive (high insurance level) multi-usage certificates for individuals
>>using strong verification procedures.
>>
>>Note: the service is to be launched ASAP and has the only
>>objective, making money by serving its subscribers well.
>>
>>Indicate your advice by the word in uppercase.
>>
>>SINGLE: A single root + possibly some CP OIDs to spice things up
>>MULTIPLE: Different roots
>>
>>Lets rock!
>>
>>
>>
>>    
>>
>--
>Joseph A. Doekbrijder
>--------------------------------------------------
>SwissSign AG
>Löwenstrasse 1, CH-8001 Zürich
>Tel: +41 43 344 88 11 Mobil: +41 79 211 24 46
>www.swisssign.com
>--------------------------------------------------
>
>
>  
>

-- 
Joseph A. Doekbrijder
--------------------------------------------------
SwissSign AG
Löwenstrasse 1, CH-8001 Zürich
Tel: +41 43 344 88 11 Mobil: +41 79 211 24 46
www.swisssign.com
--------------------------------------------------