This book presents the most interesting talks given at ISSE 2012 - the forum for the inter-disciplinary discussion of how to adequately secure electronic business processes. The topics include: - Information Security Strategy; Enterprise and Cloud Computing Security - Security and Privacy Impact of Green Energy; Human Factors of IT Security - Solutions for Mobile Applications; Identity & Access Management - Trustworthy Infrastructures; Separation & Isolation - EU Digital Agenda; Cyber Security: Hackers & Threats Adequate information security is one of the basic requirements of all electronic business processes. It is crucial for effective solutions that the possibilities offered by security technology can be integrated with the commercial requirements of the applications. The reader may expect state-of-the-art: best papers of the Conference ISSE 2012. Content Information Security Strategy - Enterprise and Cloud Computing Security - Security and Privacy - Impact of Green Energy - Human Factors of IT Security - Solutions for Mobile Applications - Identity & Access Management - Trustworthy Infrastructures - Separation & Isolation - EU Digital Agenda - Cyber Security - Hackers & Threats Target Group Developers of Electronic Business Processes IT Managers IT Security Experts Researchers The Editors Norbert Pohlmann: Professor for Distributed System and Information Security at Westfalische Hochschule Gelsenkirchen Helmut Reimer: Senior Consultant, TeleTrusT Wolfgang Schneider: Senior Adviser, Fraunhofer Institute SIT