  E-business, information serving, and ubiquitous computing will create heavy
request traffic from strangers or even incognitos. Such requests must be
managed automatically. Two ways of doing this are well known: giving every
incognito consumer the same treatment, and rendering service in return for
money. However, different behavior will be often wanted, e.g., for a university
library with different access policies for undergraduates, graduate students,
faculty, alumni, citizens of the same state, and everyone else.
  For a data or process server contacted by client machines on behalf of users
not previously known, we show how to provide reliable automatic access
administration conforming to service agreements. Implementations scale well
from very small collections of consumers and producers to immense client/server
networks. Servers can deliver information, effect state changes, and control
external equipment.
  Consumer privacy is easily addressed by the same protocol. We support
consumer privacy, but allow servers to deny their resources to incognitos. A
protocol variant even protects against statistical attacks by consortia of
service organizations.
  One e-commerce application would put the consumer's tokens on a smart card
whose readers are in vending kiosks. In e-business we can simplify supply chain
administration. Our method can also be used in sensitive networks without
introducing new security loopholes.
