[cap-talk] "Ambient capability"

[David-Sarah Hopwood]

Kevin Reid wrote:
> On Jul 11, 2009, at 0:38, David-Sarah Hopwood wrote:
>> Kevin Reid wrote:
>>> Someone just wrote this page on the erights.org wiki:
>>>
>>>   http://wiki.erights.org/wiki/Ambient_capability
>>>
>>> I've never seen this term before and the description feels a little
>>> off. Would the scholars and taxonomists of cap-talk please review/ 
>>> edit this article?
>>
>> I don't understand what this page is trying to say either. The term
>> "capability" should be reserved for an actual capability (first-class
>> value that combines an object designator and authority to that  
>> object); this page seems to be using it differently.
>>
>> At first sight, having permissions vary "by virtue of context" seems
>> like an antipattern in any capability system.
> 
> Further info: User:Dmbarbour, the author of this page, also wrote a  
> definition of "Object capability". They claim to be a scholar of  
> capabilities. They have been somewhat antagonized by User:Kosik.
> 
> I am concerned about a shortage of viewpoints from the wider cap-talk  
> community.
> 
> Any of you with time, please review these pages and their histories  
> (especially the editing of [[Object capability]]) and contribute.
> 
> http://wiki.erights.org/wiki/Talk:Object_capability
> http://wiki.erights.org/w/index.php?title=Object_capability&action=history

The definition added by User:Dmbarbour was:

# For [http://en.wikipedia.org/wiki/Object-capability_model
# object-capability model security], object capabilities are secured
# by making them unforgeable (often via type system) or very difficult
# to guess (necessary for distributed objects).

This is incorrect; "very difficult to guess" is not sufficient for an
object-capability (by definition; see MarkM's thesis, which introduced
the term specifically in order to distinguish "unforgeable" from
"difficult to guess"). Much of the rest of the text added by Dmbarbour
and removed by User:Kosik in
<http://wiki.erights.org/w/index.php?title=Object_capability&diff=3516&oldid=3506>,
was also nonsensical or confusing. I might have made a similar edit,
and I agree with pretty much everything Kosik says in the Talk pages.

I do appreciate your implied concern about the tone of responses to
new contributors. But it really does not help to let clearly incorrect
definitions stand, just to avoid the potential of antagonising such
contributors.

> http://wiki.erights.org/wiki/Capability
> http://wiki.erights.org/wiki/Talk:Capability

-- 
David-Sarah Hopwood  ⚥  http://davidsarah.livejournal.com