The increasing spread of personal information on the Internet calls for new tools and paradigm to complement the concealment and protection paradigms. One such suggested paradigm is transparency and the associated transparency enhancing tools, making it possible for Data Subjects to track an examine how there data have been used, where it originates and what personal data about them that Data Controllers have stored. One such tool needed in order to track events related to personal data is a log system. Such a log system must be constructed in such a way that it does not introduce new privacy problems. This chapter describes such a log system that we call a privacy preserving secure log. It outlines the requirements for the system and describes and specifies a privacy preserving log system that has been developed and implemented within the Prime Life project.