Payments as an answer to spam

[Dan Geer]

>   ... snip ...
>   good analysis.  It's the classic reason why any payment system is
>   cursed as an antispam system.  That latency between value retrieval
>   and propagation of that status is the real killer.  As you point
>   out, a secondary killer is the number of queries one needs to make
>   against a coin/stamp/check verifier.
>   ... snip ...

Noting the close similarity between spam and denial of service,
it is worth remembering that there is a fundamental tradeoff
between authorization requirements and vulnerability to DoS
in that the work factor I can impose on you is proportional
to the amount of labor I can cause you to voluntarily perform
before you can make your GO/NOGO decision on my authorization
for further service.  Adding work factor the better to ensure
that no unauthorized services are performed paradoxically
increases your vulnerability to DoS in that I can ask for
that pre-authz work to be done as often as I like.

--dan


---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com