[cap-talk] Is EQ necessary for PetName systems?

[Bill Frantz]

tribble at e-dean.com (Dean Tribble) on Saturday, October 20, 2007 wrote:

>I just realized that in a system that used coercing-EQ consistently, it
>might be possible to integrate resume keys smoothly: the one coercion
>message consumes the resume, key, but the result of the coercion is a new
>resume key coerced appropriately. thus, when the coercion is complete the
>caller is left with one, single-use key.
>
>On 10/20/07, Dean Tribble <tribble at e-dean.com> wrote:
>>
>> On 10/19/07, Jonathan S. Shapiro <shap at eros-os.com> wrote:
>> >
>> > There is one case where EQ appears to be necessary. This has nothing to
>> > do with pet names. In KeyKOS/EROS, invoking a resume capability destroys
>> > it. In such
>> > systems, there must be some comparator operation that can compare two
>> > capabilities for equality without invoking the capabilities.
>>
>>
>> This is an interesting constraint. This constraint would also require that
>> brand checking operations to have magic (i.e., non-message-based) access
>> for checking brands, correct?
>>
>>

One problem with generating a new resume key on use of the coercing-EQ
operation is that other holders of the original key would notice that
their keys were destroyed.

Cheers - Bill

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