Don't worry about online vs offline transactions. The credit card companies are moving toward all online transactions. A company down in NJ called RAM Mobile Data is helping them on this. They have base stations in 90% of urban business areas. The radios are fairly cheap (even though they need an appropriate thing to plug them into) and the per-transaction charges are about a dime. So I would say that the important problem to solve is "how do we make accounts anonymous?" rather than "how do we avoid double-spending?" -russ <nelson@crynwr.com> ftp.msen.com:pub/vendor/crynwr/crynwr.wav Crynwr Software | Crynwr Software sells packet driver support | ask4 PGP key 11 Grant St. | +1 315 268 1925 (9201 FAX) | Quakers do it in the light Potsdam, NY 13676 | LPF member - ask me about the harm software patents do.