Re: [freehaven-dev] POKs for mix accountability transcript

[dmolnar <dmolnar@hcs.harvard.edu>]

On Wed, 3 Jan 2001 dmolnar@belegost.mit.edu wrote:

> >   2) E_pk_j(N_{j+1}, M) = C
> >   3) M was not sent to N_{j+1}
> > 
> > without giving away M or N_{j+1}. I'm not sure this is even possible.

Because 3) requires us to prove a negative, it seems that the only way we
can do this is to set out explicitly what it means for M to be "sent" to
N_{j+1}, and say that other potential methods of moving M to N_{j+1} are
not legitimate. For instance, I could deliver M to N_{j+1} by hand,
completely out of band.

What passing all messages on the ledger does for us is that it establishes
what "sent" means. A message is "sent" iff it appears on the ledger. 
As you've pointed out, this may not be desirable and perhaps not even
necessary - but it seems to allow us to achieve 3) in some sense. 

-David