Eric Hughes says:
I am trying to read and understand the Niels Ferguson "Off-line Coins" article, the "Efficient Off-line Digital Cash" paper also from CWI
Both articles, as I recall from the abstracts, exist square within the observer framework.
I think I have a scheme for real off-line payments, that is, payments that do not require an observer at the time of transaction (although they would require a couple of on line transactions in advance). They would require that people conduct transactions in a style that they are not used to, but would require no trust and would allow full anonymity of parties. Unfortunately, I don't know enough about the mathematics of Chaum's blinding schemes to know if the scheme I have in mind (which depends on his scheme) would work. Could someone point me at a reference or two on Chaum's original work? The mathematics associated with blinding is, sadly, something that I haven't spent sufficient time on. Perry