Olaf Bergmann

Olaf Bergmann Olaf Bergmann holds a Diploma in Computer Science and received his Doctor in Engineering (Dr.-Ing.) in 2007 from Universität Bremen, and received a Master in Commercial Law in 2010. Since 2009, he is a member of the communication networks research group (AG Rechnernetze) at the Universität Bremen. He has been involved in several national and international research projects in the areas of wireless and interpersonal multimedia communications, e.g., in the European FP5 IPv6 Wireless Internet Initiative (6WINIT). From 2006 to 2009, Olaf has been working for a German ISP to improve the existing Voice-over-IP platform and re-design the SIP-based presence service. Olaf also has continuously participated in IETF standardisation since 2000 and has co-authored several books on Web technologies. His current research focus is on architectures and communication protocols for challenged environments.


Lemonbeat (2016 – 2019)

Evaluation of the Constrained Application Protocol (CoAP) for a secure smart home infrastructure.

RESTLicht and Constrained-Cast (10/2011 – 12/2013)

Augmenting the practical experience with the Constrained Application Protocol (CoAP) and its limitations for control automation applications, and evaluation of various options for manageable end-to-end security within this application scenario.

CHIANTI (1/2008 – 2/2010)

Challenged Internet Access Network Technology Infrastructure: An EC FP7 project on supporting personal and vehicular mobility as well as nomadic computing incrementally in today's Internet. The base assumption is that mobility and nomadicity will lead to challenged networking conditions due to (unforeseeable) disconnections. The project develops technical solutions to support robust communications in such challenged networks with and without infrastructure assistance.

GEOBLOG (10/2005 – 3/2006)

Using regionally scoped service maps for dissemination of information on local infrastructure and events. The specific focus is on the formal description of service maps and their distribution in hybrid networks. In particular, the applicability of Internet Media Guides (IMG) is investigated, including delivery in hybrid networks via FLUTE (File Delivery over Unidirectional Transport, RFC 3926).

GEOCOOP (10/2004 – 9/2005)

An industry project on investigating location techniques and concepts for providing location-based services with the aim of enabling interpersonal communications based upon proximity. Particular consideration of privacy aspects and decentralized operation.

PASST (11/2003 – 9/2004)

Presence Aggregation System: An industry project investigating the automated (but ultimately end-user-controlled) aggregation of personal presence information from a number of sources. The project focuses on defining rule sets for presence aggregation and validating the concepts in a complete SIP-based presence infrastructure.

FETA (1/2003 – 9/2003)

Functional Enhancement for Telephony Applications: An industry project (following up on DTI) to augment stand-alone IP phones by external software components with a focus on secure multiparty peering in ad-hoc networks, conferencing, and video communications.

DTI (2/2002 – 10/2002)

Desktop-Telephony Integration: An industry project on the integration of various personal computing appliances (PC, laptop, PDA) and stand-alone IP phones, focusing on peerwise ad-hoc networking, autoconfiguration, and distributed phone control.

6WINIT (1/2001 – 12/2002)

A European project that deals with the integration of IPv6 and various wireless technologies (in particular, GRPS and UMTS) as a platform to provide mobile interactive conferencing applications in a clinical environment.

SIPHON (6/2000 – 11/2001)

SIP for telePHONy: A research project addressing script-based testing of SIP-based IP telephony endpoints (IP phones) in phase I and dealing with aspects of IP telephony to the home user in phase II.

MUSIG (5/1999 – 5/2000)

An industry project on gatewaying between different (multimedia) communications technologies and IP telephony (H.323, SIP) and integration of conventional telephony (analogue, ISDN, GSM). Development of an Mbus-based architecture for multi-way signaling (and media) gateway.

MECCANO (10/1998 – 5/2000)

A European project that deals Internet multimedia group conferencing based. Care and feeding of parts of the European Mbone as communication infrastructure and pilot use of the European ATM infrastructure. Design of an architecture for multimedia conferencing endpoints and development of the Message Bus (Mbus) as local coordination infrastructure.


A CoAP library in C

For my student's project SAHARA, I started an open-source implementation of the Constrained Application Protocol (CoAP). You can find it at libcoap.net. More information on CoAP is available at coap.technology.

tinyDTLS, a single-threaded UDP server template with DTLS

As CoAP requires some security, I started integration my single-threaded UDP server with DTLS support (initially from OpenSSL). tinyDTLS is an example how to build this in C. As time permits, OpenSSL will be replaced by an own implementation of DTLS with PSK authentication.


Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and L. Seitz, "Datagram Transport Layer Security (DTLS) Profile for Authentication and Authorization for Constrained Environments (ACE)", RFC 9202, DOI 10.17487/RFC9202, August 2022.


O. Bergmann: Strafrechtliche Aspekte der Entwicklung von Open Source Software zur Qualitätssicherung von Kommunikationssystemen im Internet. Master thesis. 2009.

O. Bergmann: A Framework for Aggregation of Presence Information Based on User-Provisioned Rules. Dissertation, 2007.

Books and Bookchapters

Stefanie Gerdes, Carsten Bormann, Olaf Bergmann: Keeping Users Empowered in a Cloudy Internet of Things. In: Ryan Ko and Kim-Kwang Raymond Choo, Editors, The Cloud Security Ecosystem, pp. 231–247 Syngress, Boston, 2015. ISBN 978-0-12-801595-7. DOI 10.1016/B978-0-12-801595-7.00011-2.

O. Bergmann, H. Wittenbrink: XML (Bd. 2) — Ausgabeerzeugung mit XSL . SPC TEIA Lehrbuch Verlag. 2006. ISBN 3-935539-07-X

O. Bergmann, C. Bormann: AJAX — Frische Ansätze für das Web-Design. SPC TEIA Lehrbuch Verlag. Oktober 2005. ISBN 3-935539-26-6. Viele Köche.

O. Bergmann, H. Wittenbrink: XML Grundlagen (Bd. 1) — Einführung in die logische Dokumentauszeichnung . SPC TEIA Lehrbuch Verlag. 2005. ISBN 3-935539-55-X.

H. Wittenbrink, W. Köhler, O. Bergmann et al.: XML. SPC TEIA Lehrbuch Verlag, Berlin, 2003. ISBN 3-935539-69-X.

C. Bormann, J. Ott, D. Kutscher und O. Bergmann: Konzepte der Internet-Technik. SPC TEIA Lehrbuch Verlag, 2002. ISBN 3-935539-52-5.

C. Bormann, J. Ott, D. Kutscher und O. Bergmann: Konzepte Content-Repräsentation & Markup-Sprachen. SPC TEIA Lehrbuch Verlag, 2002. ISBN 3-935539-58-4.


Usable Security for RIOT and the IoT. RIOT-Summit 2018, Amsterdam, NL. 2018-09-13, Slides, Video

Voice over IP (VoIP) — Stand der Technik und aktuelle Herausforderungen. Vortrag beim VDE Region Nord-West e.V., November 2005.

J. Ott, D. Kutscher und O. Bergmann: SIP Voice Services for Intermittently Connected Users in Wireless Networks. Upperside Wi-Fi Voice Conference 2004. May 2004.


Saia, R.; Carta, S.; Bergmann, O. Wireless Internet, Multimedia, and Artificial Intelligence: New Applications and Infrastructures. Future Internet 2021, 13, 240. DOI 10.3390/fi13090240

S. Stadler, S. Gerdes, O. Bergmann: Privacy-enhanced Authentication for the Internet of Things. In: Proceedings of the 18. GI/ITG KuVS FachGespräch SensorNetze, FGSN 2019, Magdeburg, Germany, p. 37-40. DOI 10.25673/28428

Stefanie Gerdes, Olaf Bergmann, Carsten Bormann: Avoiding Gaps in Authorization Solutions for the Internet of Things. In: Proceedings of the NDSS Workshop on Decentralized IoT Security and Standards (DISS) 2018, DOI 10.14722/diss.2018.23006

Stefanie Gerdes, René Hummen, Olaf Bergmann: Autorisierungsmanagement für das Internet of Things. In: Peter Schartner, Kerstin Lemke-Rust, Markus Ullmann (Hrsg.): D·A·CH Security 2015, pp. 397–408. syssec, 2015.

Carsten Bormann, Stefanie Gerdes, Olaf Bergmann: Clearing off the Cloud over the Internet of Things. In: Proceedings of the W3C/IAB Workshop on Strengthening the Internet Against Pervasive Monitoring (STRINT), 28 February – 1 March 2014, London.

Stefanie Gerdes, Olaf Bergmann, Carsten Bormann: Delegated Authenticated Authorization for Constrained Environments. In: Proceedings of the 2014 IEEE 22nd International Conference on Network Protocols (ICNP 2014), pp. 654–659 (2014).

Olaf Bergmann, Carsten Bormann, Stefanie Gerdes: REST-based Access to SMIv2-structured Information on Constrained Devices. In: 2014 IEEE Network Operations and Management Symposium (NOMS), Krakow (2014).

Stefanie Gerdes, Olaf Bergmann: Security Requirements for Managing Smart Objects in Home Automation. In: A. Timm-Giel et al. (Eds.): MONAMI 2012, LNICST 58, pp. 231–243. Institute for Computer Sciences, Social Informatics and Telecommunications Engineering (2013).

Olaf Bergmann, Stefanie Gerdes, Silke Schäfer, Florian Junge, Carsten Bormann: Secure Bootstrapping of Nodes in a CoAP Network. In: Proceedings of the WCNC 2012 Workshop on the Internet of Things Enabling Technologies, Embracing Machine-to-Machine Communications and Beyond. April 2012, pp. 220–225. DOI 10.1109/WCNCW.2012.6215494

Olaf Bergmann; Kai T. Hillmann; Stefanie Gerdes: A CoAP Gateway for Smart Homes. In: Proceedings of the IEEE Conference on Computing, Networking and Communications, Communication Software and Services Symposium (ICNC) 2012. pp. 446–450. DOI 10.1109/ICCNC.2012.6167461

Stefanie Gerdes, Olaf Bergmann: Nutzerfreundliche Authentisierung für den Krankenhausalltag. In: Peter Schartner, Jürgen Taeger (Hrsg.): D·A·CH Security 2011. syssec, 2011, pp. 470–479.

Koojana Kuladinithi, Olaf Bergmann, Thomas Pötsch, Markus Becker and Carmelita Görg: Implementation of CoAP and its Application in Transport Logistics. In Proc. of 'Extending the Internet to Low power and Lossy Networks' (IP+SN 2011). Chicago, USA. 11th of April 2011. Paper Presentation Slides.

Stefanie Gerdes; Olaf Bergmann: Building a Test Environment for Emulating Link Characteristics of Disruptive Networks. In: Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC) 2010. DOI 10.1109/WCNC.2010.5506341

Olaf Bergmann, Stefanie Gerdes, Jörg Ott, Nils Seifert, Caleb Carroll, Nigel Wallbridge: Dealing With Disruptions: Providing Internet Access to Mobile Users on a Train (extended abstract). Proceedings of the first conference "ICT that makes the difference", Brussels, Belgium, November 2009.

Jörg Ott, Nils Seifert, Caleb Carroll, Nigel Wallbridge, Dirk Kutscher, Olaf Bergmann: The CHIANTI Architecture for Robust Mobile Internet Access. Proceedings of the 10th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), Industry Track, Kos, Greece, June 2009.

O. Bergmann, J. Ott und Dirk Kutscher: A Script-based Approach to Distributed Presence Aggregation. In: Proceedings of the IEEE WirelessCom 2005 Conference. Maui, HI. June 2005.