te. For new-style applets or information bites, the cost of validating the transaction is likely to be far larger than the su
m transferred.
A research group at Digital Equipment is working on one elegant solution, a lightweight commerce protocol, called Millicent, that has overhead low enough to handle transactions of less than a cent. The key to Millicent is that every vendor issues its own private digital cash, called scrip, which it can authenticate locally (i.e., without having to call a bank or credit card bureau) since the vendor issued it itself. You buy the scrip that you will spend from a broker who buys and sells the scrip of many different vendors. You settle your account with your broker in real cash, by which time your many small purchases have accumulated into a sum big enough to eat up the transaction overhead. Vendors will have to settle accounts with only a handful of brokers rather than with thousands of customers, and you will have to deal only with one or two brokers instead of dozens of different vendors. Millicent employs a simple cryptographic key system that provides a reasonable level
of security, adequate to the small sums transferred.
Meanwhile SunLabs is working on JavaWallet, a software framework that can incorporate and organize all these different types of electronic commerce and consolidate all their bills into one; you might use Millicent for micropayments and Secure Electronic Transactions (SET) for big purchases. JavaWallet would let you set a limit (say, $10), and it then rings a bell when you've spent that much during casual browsing.
Who Pays? And How?
