I'm not sure millicent is the most economical way to build a
micropayment system.
The use of the novel approach of investing resources to overcome a
threshold in cost of computing collisions whilst technically
interesting doesn't seem to add anything to a micropayment system
functionally or economically. Indeed the magnitude of the investment
required to reach a large enough threshold to resist forgery means
that millicent damages the economic viability of building a
micropayment system.
Effectively the threshold is bought by being willing to burn more
money than the estimated forger is willing to spend. Whilst this
approach may be succesful in practice with a largish investment, a
micropayment system functionally identical could be built using
conventional approaches more economically.
This therefore begs the question of why?
I'm not sure the argument that it would improve investor confidence to
see a large financial barrier to entry errected is economically and
technically accurate -- there is nothing compelling competitors to use
the millicent protocol, and so they can undercut millicents pricing by
using conventional micropayments techniques having lower setup and
recurring costs.
Hashcash also relies on a similar collision function, however the
point there is to achieve distributed minting, and so the cost is
distributed, and seen as a side effect incurred to achieve the
decentralisation of control. Millicent does not make use of
opportunities for distributing overhead, and so incurs the overhead
without gaining the decentralised architecture.
Wei Dai's b-money protocol similarly makes use of a distributed
minting function.
Adam
