- ABC4Trust - Attribute Based Credentials for Trust (coordinator).
- GINI S.A. - Global Identity Networking of Individuals.
- PICOS - Privacy and Identity Management for Community Services.
- Chair of IFIP WG 11.2 - Pervasive Systems Security (since June 2013).
- Member of ENISA Experts Group in "Internet of Things, Ubiquitous environments" and "Electronic identity" (since May 2013).
- Member of the experts’ panel at the EU Commission’s Stakeholder Group on the implementation of a "Regulation on electronic identification and trust services", Brussels, 25 September 2013.
- Invited Expert - First plenary meeting of the Public-Private Platform on Network and Information Security (NIS Platform), European Commission, Brussels, 17 June 2013.
- Member of Task Force 3 "Big Data and Data Minimization" of the "IDENTITY | Talk in the Tower" initiative (since June 2013).
- Member of the Editorial Board, Journal of Trust Management, Springer.
- Co-organizer - Dagstuhl Seminar 13312: "My Life, Shared - Trust and Privacy in the Age of Ubiquitous Experience Sharing", 28 Jul. — 02 Aug. 2013.
- TPC Co-chair - International Conference on Privacy and Security in Mobile Systems (PRISMS 2013), 24-27 June 2013, Atlantic City, NJ, USA.
- TPC Co-chair - 4th International ICST Conference on Security and Privacy in Mobile Information and Communication Systems (MobiSec 2012), 25 June 2012, Frankfurt, Germany.
- Coordinator - Dagstuhl Perspectives Workshop 11061: Online Privacy: Towards Informational Self-Determination on the Internet, 6-11 February, 2011.
- Track Co-Chair - The 6th Mediterranean Conference on Information Systems (MCSI 2011), Cyprus, 3–5 September, 2011.
- Member of the Expert Panel - EU Project TAS3 (Trusted Architecture for Securely Shared Services), 17-18 November 2011, Nice, France.
- Invited Expert - Stakeholder Workshop on "Digital Agenda for Europe: Electronic identification, authentication and signatures in the digital single market", 25 September 2013, 10 March 2011 and 3 October 2011.
- Advising Member of the SENSYBLE Doktorandenkolleg (Goethe University Frankfurt - University of Applied Sciences Wiesbaden)
Program Committee Member
- The 29th IFIP TC-11 SEC 2014 International Information Security and Privacy Conference, Marrakech, Morocco, 2-4 June 2014.
- The IEEE International Conference on Communications (ICC 2014) - Communications and Information Systems Security Symposium, Sydney, Australia, 10-14 June 2014.
- The 9th IEEE International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP 2014), Participatory Sensing and Crowdsourcing track, Singapore, 21-24 April 2014.
- The 8th IFIP Workshop in Information Security Theory and Practice (WISTP 2014) - Securing Internet of Things, Heraklion, Greece, June 23-25, 2014.
- ENISA/EC Annual Privacy Forum 2014 - Closing the loop from research to policy, Athens, 20-21 May 2014.
- Sicherheit: Schutz und Zuverlässigkeit (GI SICHERHEIT 2014), Vienna, Austria, 19-21 March 2014.
- IFIP Summer School 2013 - The 8th International IFIP Summer School on Privacy and Identity Management for Emerging Services and Technologies, Nijmegen, the Netherlands, 17-21 June, 2013.
- The 28th IFIP TC-11 SEC 2013 International Information Security and Privacy Conference, Auckland, New Zealand, 8-10 July 2013.
- The Eighth International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC 2013), Security Track, Compiegne, France, 28-30 October 2013.
- The Second International Workshop on Resilience and IT-Risk in Social Infrastructures (RISI 2013), September 2nd – 6th, 2013, Regensburg, Germany.
- The 11th Smart Card Research and Advanced Application Conference (CARDIS 2012), Graz, Austria, 28–30 November 2012.
- The 9th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (IEEE MASS 2012), Las Vegas, Nevada, US, October 2012.
- The 11th International Conference on Wirtschaftsinfomatik (WI 2013), Leipzig, Germany, 27.02 - 01.03.2013.
- The 2nd International Conference on Sensor Networks (SENSORNETS 2013), Barcelona, Spain, 19-21 February 2013.
- The 1st ACM Workshop on "High Performance Mobile Opportunistic Systems" (HP-MOSys 2012), to be held in conjunction with MSWIM 2012, Paphos, Cyprus, October 21-25 2012.
- The 14th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS 2012) - Safety and Security Track, Toronto, Canada, 24-27 September 2012.
- The 1st International Workshop on Cybersecurity of Online Social Networks (CSOSN 2012), Istanbul, Turkey, 26-29 August 2012.
- The 1st International Conference on Sensor Networks (SENSORNETS 2012), Rome, Italy, 24-26 February 2012.
- IEEE Global Communications Conference (IEEE GLOBECOM 2011) second Workshop on Ubiquitous Computing and Networks (UbiCoNet 2011), Houston, TX, December 9, 2011.
- The 8th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (IEEE MASS 2011), Valencia, Spain, October 17-22, 2011.
- IFIP SEC 2011 - Future Challenges in Security and Privacy for Academia and Industry, Lucerne, Switzerland, 7-9 June 2011.
- The 4th International Conference on Mobile Ubiquitous Computing, Systems, Services and Technologies (UBICOMM 2010), Florence, Italy, October 25 - 30, 2010.
- Sicherheit – Schutz und Zuverlässigkeit (SICHERHEIT 2010), Berlin, Germany, October 5-7, 2010.
- The 5th International ICST Conference on Security and Privacy in Communication Networks (SECURECOMM '09), Athens, Greece, September 14-18 2009.
- The 2009 International Conference on Wireless Networks (ICWN '09), Las Vegas, Nevada, USA, July 13-16 2009.
- The Third International Conference on Mobile Ubiquitous Computing, Systems, Services and Technologies (UBICOMM '09), Sliema, Malta, October 11-16 2009.
- The Second International Conference on Mobile Ubiquitous Computing, Systems, Services and Technologies (UBICOMM '08), Valencia, Spain, September 29 - October 4.
- Panel Presentation, "Trustworthy Infrastructure for Personal Data Management", Digital Enlightenment Forum 2013, 18-20 September 2013, Brussels, Belgium.
- Presentation, "The ABC4Trust Architecture - Making Privacy-ABCs Deployable and Interoperable", Cyber Security and Privacy EU Forum 2013, Brussels 18-19 April 2013.
- Panel Presentation, "Trust Frameworks: Are We Being Misdirected By The 3-Party Model?", RSA Conference 2013, February 25 - March 1, San Francisco.
- Panel Presentation on EU Digital Agenda (GINI-SA Roundtable), iSSE 2012, 23-24 October 2012, Brussels.
- Presentation, "Privacy and Trust in Participatory Sensing", IFIP WG 11.2 : Seminar 2012, July 4th, 2012, Nijmegen, The Netherlands.
- Presentation, "Attribute-based credentials for social networks and qualified feedback. ABC4 Trust - concepts and trials", 2012 IBM Academic Days Conference, 14-15 May, Frankfurt.
- Presentation, "My Life, Shared - Privacy and Trust in Mobile Participatory Sensing", Informatik Research Seminar, Darmstadt University, 11 May 2012, Darmstadt, Germany.
- Panel Presentation "What ABC4Trust can do for Privacy in eID", European Identity & Cloud Conference (EIC 2012), 17-20 April 2012, Munich, Germany.
- Keynote Speaker on "Minimal disclosure and anonymous credentials", 4th ENISA Summer School on Network & Information Security, 27 June - 1 July 2011, Crete, Greece.
- Panel Presentation on ABC4Trust Architecture, 1st Digital Enlightenment Forum on The Future of European Electronic Identity Management, 31 October 2011, Paris, France.
- Panel Presentation on Human oriented approaches to security, privacy and trust, BIC Annual Forum - Building International Cooperation for Trustworthy ICT, 29 November 2011, Brussels, Belgium.
- Presentation, "Participatory Sensing: New Opportunities and Privacy Challenges", Practical Aspects of Security (PRACSE 2010), 14-15 October 2010, Athens, Greece.
Reviewer for program committees/journals
- Member, IFIP WG 11.2 on Pervasive Systems Security.
- Member, IEEE Computer Society.
- Member, GI (German Society of Computer Science, e.V.).