[fc-discuss] Financial Cryptography Update: On Digital Cash-like Payment Systems

[cyphrpunk]

One other point with regard to Daniel Nagy's paper at
http://www.epointsystem.org/~nagydani/ICETE2005.pdf

A good way to organize papers like this is to first present the
desired properties of systems like yours (and optionally show that
other systems fail to meet one or more of these properties); then to
present your system; and finally to go back through and show how your
system meets each of the properties, perhaps better than any others.
This paper is lacking that last step. It would be helpful to see the
epoint system evaluated with regard to each of the listed properties.

In particular I have concerns about the finality and irreversibility
of payments, given that the issuer keeps track of each token as it
progresses through the system. Whenever one token is exchanged for a
new one, the issuer records and publishes the linkage between the new
token and the old one. This public record is what lets people know
that the issuer is not forging tokens at will, but it does let the
issuer, and possibly others, track payments as they flow through the
system. This could be grounds for reversibility in some cases,
although the details depend on how the system is implemented. It would
be good to see a critical analysis of how epoints would maintain
irreversibility, as part of the paper.

CP