The Internet and the World Wide Web (WWW) play an increasingly imp- tant role in our today s activities. More and more we use the Web to buy goods and to inform ourselves about cultural, political, economical, medical, and scienti?c developments. For example, accessing ?ight schedules, me- cal data, or retrieving stock information become common practice in today s world. Many people assume that there is no one who watches them when accessing this data. However,sensitive userswho accesselectronic shops(e-shops) might have observedthat this assumptionoften isnot true. In many cases,E-shopstrack the users accessbehavior when browsingthe Web pagesof the e-shopthus deriving accesspatterns for individual shoppers. Therefore,this knowledge on access behavior and access patters allows the system to tailor access to Webpagesforthatusertohis/herspeci?cneedsinthefuture.Thistrackingof usersmightbeconsideredharmlessand acceptable inmanycases.However, in cases when this information is used to harm a person - for example about the person s health problems - or to violate his/her privacy (for example ?nding out about his/her ?nancial situation), he/she would like to be sure that such tracking is impossible to protect the user s rights.