1 Executive Summary

The Snowden revelations have demonstrated that the US and other nations are amassing data about people’s lives at an unprecedented scale. Furthermore, these revelations have shown that intelligence agencies are not only pursuing passive surveillance over the world’s communication systems, but are also seeking to facilitate such surveillance by undermining the security of the internet and communications technologies. Thus the activities of these agencies threatens not only the rights of individual citizens but also the fabric of democratic society. Intelligence services do have a useful role to play in protecting society and for this need the capabilities and authority to perform targeted surveillance. But the scope of such surveillance must be strictly limited by an understanding of its costs as well as benefits, and it should not impinge on the privacy rights of citizens any more than necessary. Here we report on a recent Dagstuhl Perspectives Workshop addressing these issues – a four-day gathering of experts from multiple disciplines connected with privacy and security. The meeting explored the scope of mass-surveillance and the deliberate undermining of the security of the internet, defined basic principles that should underlie needed reforms, and discussed th