ISPA - Internet Service Providers Austria - had charged a team of software engineers of the University of Vienna, Austria, to confront the data storage requirements of the EU Data Retention Directive in the fields of Internet access, Internet e-mail and Internet telephony with state-of-the-art Internet technology.

The outcome of the study, presented in this book, demonstrates a series of inconsistencies in the legal framework of the Directive which has to be implemented by 15 March 2009 at latest concerning Internet data. The Directive does not define the affected data in detail at a technical level. Although the storage of content data is explicitely forbidden, this requirement may be blurred by the fact that the border between content and traffic or location data is difficult to discern in electronic communication.

The authors assume that for a "model ISP" serving 500.000 customers an additional storage space of about 706 gigabytes is needed to retain the data over a six months period. This amounts to additional costs of about EUR 970.000 for setup and operation in the first year and EUR 465.000 in every subsequent year. Almost 60 % of the storage space would be used for data originating from spam messages irrelevant for the purposes of the Directive.  

Whereas the data concerning Internet access is to a large extent available from a technical point of view the situation is quite different for Internet e-mail and Internet telephony. SMTP protocol data may be manipulated, location data may be faked. Basic technology is readily available for circumventing data retention and it is impossible to trace web mail communication via a provider resident outside the EU. So the authors conclude that there is the danger of achieving a rather low efficiency with the measures specified in the Directive.