Re: [pkix] Managing Long-Lived CA certs

["Dr. Pala" <[e-mail]>]

Hi Rob,

I was thinking about that but wouldn't it prevent using the key for 
other reasons like signing CRLs ? I know you can have a separate CRL 
signer, but I would like to limit _only_ the issuing of certificates, 
not other usages.

Cheers,
Max


On 7/17/17 4:49 PM, Rob Stradling wrote:
> Hi Max.
>
> The "Private Key Usage Period" extension was present in RFC2459 and 
> RFC3280 (see section 4.2.1.4), but was removed in RFC5280. (Well, 
> mostly removed; the ASN.1 definitions are still in Appendix A.2 ;-) ).
>
> On 17/07/17 15:19, Dr. Pala wrote:
>> Hi PKIX,
>>
>> I have a small question for the list regarding long-lived CA 
>> certificates. Especially in the context of device certificates, we 
>> often see the use of extra long-lived certificates for Root and Sub 
>> CAs (e.g., 35+ years) combined with limited key sizes (e.g., p256).
>>
>> Until we have a supported mechanism for reprovisioning devices (...), 
>> one possible solution for limiting the exposure of the private key 
>> would be to have a scoped certificate issuance period.
>>
>> What I am thinking about would be adding an extension that says: 
>> "This CA can issue certificates from up to 5 years from the 
>> validFrom, after this, just use it to provide revocation 
>> information". This might provide some protection in case the CA key 
>> is compromised after the initial 5 years of validity (e.g., 
>> certificates issued after that date shall be rejected).
>>
>> Does such extension exists today ? If not, could this be some work 
>> for LAMPS/SPASM WG ?
>>
>> Cheers,
>> Max
>>
>> -- 
>> Best Regards,
>> Massimiliano Pala, Ph.D.
>> OpenCA Labs Director
>> OpenCA Logo
>>
>>
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>> https://www.ietf.org/mailman/listinfo/pkix
>>
>

-- 
Best Regards,
Massimiliano Pala, Ph.D.
OpenCA Labs Director
OpenCA Logo