Re: [Anima-bootstrap] brsky concern1: separating audit-log retrieval from voucher generation

I see this as the same discussion for “concern2” so please look to that thread for responses.

- max

> On Nov 1, 2016, at 2:15 PM, Toerless Eckert <tte+ietf@cs.fau.de> wrote:
> 
> As discussed today on the call, restated for the rest of the team with more detail:
> 
> -> pledge connects to two networks, A, B.
> -> Pledge tries to well-behave, only offers nonce to one network first, A.
> -> (registrar of) A gets voucher. A looks at audit-log. Audit log is fine.
>   Ultimately, A decides  not to enroll pledge though.
> -> Pledge offers nonce to B, B gets voucher and audit-log.
>   Audit log shows A, so B is concerned. B rejects device.
>   Without the entry in audit log, B would have enrolled device.
> 
> My worry is that the current audit log approach can too easily create
> false positives that will make enrolment fail if a device has multiple network
> connections:
> 
> It's impossible for A to get an audit-log without also getting
> a voucher, which in return would make another domain suspicious and likely
> make it decide not to accept the device.
> 
> Separating out request for voucher from request for audit-log could work like this:
> 
>  A->MASA: request audit-log for (pledge,nonce1)
>  MASA:    audit-log entry: "A requested audit log for pledge, hash(nonce1)" [1]
>  MASA->A: reply: audit-log
> 
>  ... A makes up its mind if it wants pledge and decides that it does NOT.
> 
>  -> A doesn't do anything more. Audit log would show B that A did see device,
>     but also that A never got voucher so that it could not have modified
>     device == B will happily enroll pledge.
> 
> 
>  ... A makes up its mind if it wants pledge and decides that it does want to:
> 
>  A->MASA: request voucher for (pledge,nonce1)
>  MASA:    Examine audit-log that no voucher was granted since the audit-log
>           was given to A [1]. requests for audit-logs since [1] are
> 	   ignored in this determination.
>  MASA->A: If audit-log ok:
>           reply OK: voucher(nonce1)
>           audit-log entry: "A received voucher for pledge, hash(nonce1)" [2]
> 
> 	   If audit-log nok:
>           reply NOK: audit-log
>           audit-log entry: "A failed voucher request for pledge, hash(nonce1), hash(nonce2)"
> 	   hash(nonce2) would be from an audit-log entry that did happen after
> 	   [1] and 
> 
> 
> Cheers
>    Toerless
> 
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