[ Thanks to Markus Sulzbacher for
this link. ]
“HTTP cache-control headers such as If-Modified-Since allow
servers to track individual users in a manner similar to cookies,
but with less constraints. This is a problem for user privacy
against which browsers currently provide little
protection.”
“Some people would like to be anonymous as they use the web, and
other people would like to prevent anonymous access for various
reasons. Consider, for example, an internet marketing company that
wants to chain together visits to various web sites by a user so as
to build a fuller profile of their interests and usage patterns.
Conversely, a web user might not wish to leak such information to a
site because they are looking at controversial information, desire
a good negotiating position, or see privacy as a moral right.”
“An arms race in techniques for providing and stripping away
anonymity has developed over the years. This black paper discusses
what is believed to be a new technique for tracking clients and
possible responses.”