Re: [ogpx] Seed capability behavior

[Arrogant Cyberstar <[e-mail]>]

On Wed, Jan 20, 2010 at 4:56 PM, Hogmanay Milestone <
[e-mail]> wrote:

>
> >>>>1.2. if the seed cap persists for a fixed period of time, it allows
> >>>>service caps to have shorter lifetimes. deployers may want some caps
> >>>>(like caps for spending money and transferring items) to have a
> >>>>shorter lifetime than others (like caps for connecting to public
> >>>>regions or caps for getting the grid status.)
> >>>>
> >>>>by persisting the seed cap, the client may request a new service cap
> >>>>from the seed without having to re-authenticate.
> >>
> >>
> >>you could request a "new seed" capability from the seed cap, then when
> you need a >new one, you access the new seed capability to give you a new
> seed capability.
> >>
> >>
> >>
> >
> >how is this different from just keeping the seed cap around? if the
> concern is that an >attacker will be able to exploit a security
> vulnerability to access a seed cap, then it >could just as easily extract
> the "new seed" cap instead of the seed cap. the attacker >could then use the
> new seed cap  to get another seed cap, and the client is still pwnd.
>
> but keeping the same seed cap would mean it's easier for someone to guess
> it.
>

the docs so far suggest that caps are 128 bit uuid's. if you're going to
guess, you only have a 2^-128 chance of guessing correctly. by comparison,
the chance that a gamma ray burst will cause a mass extinction event today
is 2.7 * 10 ^ -12 (or about 2^-39)