Re: Hash cash keys

On Sunday 02 March 2008 12:49, bbackde-gM/[email protected] wrote:
> No complains from anyone? So we can expect this feature soon?

We're in a feature freeze. That means you have to convince me that it's 
essential to have this for 0.7.0. Hash cash is not a panacea: IMHO it will 
have to be combined with CAPTCHAs and web of trust, therefore we will still 
need FMS. Because an attacker will probably have a powerful system, whereas a 
lot of users don't; an attacker might have native-optimised hashcash 
libraries, and a typical user won't, at least in the short term. A user might 
not be willing to wait more than 1 minute for a message's hashcash to be 
computed, on a slow system; this means an attacker can solve them every 5 
seconds on a faster system (twice the clock speed and four cores).

Hash cash can be implemented in FMS without any change to the core. And it 
should only be necessary for FMS introductions, not later on. Just bolting it 
on to Frost would mean a very weak protection, at the cost of a new keytype. 
On the other hand it's a nice idea...
> 
> On Sat, Mar 1, 2008 at 9:05 PM,  <bbackde-gM/[email protected]> wrote:
> > This sounds like a good idea! No matter who uses it (fms, frost, thaw)
> >  could at least be sure
> >  that the sending costed the sender some cpu time. It could also
> >  restrict the amount of sent messages
> >  at all, considering the same cpu time. So it becomes more expensive
> >  and annoying for the spammer.
> >  Now its quite easy for him, he could even play crysis in parallell ;)
> >
> >  On Sat, Mar 1, 2008 at 8:56 PM, Michael Rogers <m.rogers-kecf2yCh/[email protected]> 
wrote:
> >  > bbackde-gM/[email protected] wrote:
> >  >  > If I understand this correct, the node of the sender will have to
> >  >  > compute a valid
> >  >  > hash cash before actually sending the key? And receivers can easily 
check the
> >  >  > hash cash and reject keys without a valid hash cash?
> >  >
> >  >  Right - inserts without valid hash cash won't even be forwarded.

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