Hi Thomas,

this is not a discus and I’m fine your reply. Still a few more comments:

> Am 31.10.2016 um 15:37 schrieb Thomas C. Schmidt <[email protected]>:
> 
> Hi Mirja,
> 
> you are right in the sense that (a) if all previous evaluations have been 
> performed without a failure, and (b) if no revocation occurred (or (c) a 
> previous revocation has cleaned up all further delegation entries), then the 
> write procedure can rely on the single delegation entry that matches the 
> current user name of the writer.

This comes down to me to only one ‚if‘ and that is actually point c. And I’d 
hope that c would always happen.

> 
> However, this includes several "ifs". For instance, if cleanup of the 
> delegation list has not been completed at the time of granting write access, 
> errors in the trust chain may occur. This could introduce unwanted attack 
> surface.

Could you document this attack surface in the doc…?

> 
> Our rationale behind designing this complete, self-contained procedure was 
> (a) writing an ACL list is not a frequent operation (so complexity is not the 
> major concern), and (b) keeping all operations simple, robust, and of minimal 
> dependence w.r.t. each other.

Don’t you have to do the check every time you check write access for a shared 
resource? That can be much more often.

Mirja


> 
> That's why it's like that.
> 
> Cheers,
> Thomas
> 
> On 31.10.2016 15:06, Mirja Kuehlewind wrote:
>> Mirja Kühlewind has entered the following ballot position for
>> draft-ietf-p2psip-share-09: No Objection
>> 
>> When responding, please keep the subject line intact and reply to all
>> email addresses included in the To and CC lines. (Feel free to cut this
>> introductory paragraph, however.)
>> 
>> 
>> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
>> for more information about IESG DISCUSS and COMMENT positions.
>> 
>> 
>> The document, along with other ballot positions, can be found here:
>> https://datatracker.ietf.org/doc/draft-ietf-p2psip-share/
>> 
>> 
>> 
>> ----------------------------------------------------------------------
>> COMMENT:
>> ----------------------------------------------------------------------
>> 
>> Quick questions on sec 6.3. (Validating Write Access through an ACL):
>> Do I really need to validate the authorization chain in the ACL every
>> time I give access to a resource? Wouldn't I rather validate the ACL when
>> it's modified and then simply assume that it is sufficient that I have an
>> entry in the ACL to provide access?
>> 
> 
> -- 
> 
> Prof. Dr. Thomas C. Schmidt
> ° Hamburg University of Applied Sciences                   Berliner Tor 7 °
> ° Dept. Informatik, Internet Technologies Group    20099 Hamburg, Germany °
> ° http://www.haw-hamburg.de/inet                   Fon: +49-40-42875-8452 °
> ° http://www.informatik.haw-hamburg.de/~schmidt    Fax: +49-40-42875-8409 °
> 

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