This book presents the proceedings of the 6th International Conference on Trust, Privacy and Security in Digital Business (TrustBus 2009), held in Linz, Austria d- ing September 3-4, 2009. The conference continues from previous events held in Zaragoza (2004), Copenhagen (2005), Krakow (2006), Regensburg (2007) and Turin (2008). The advances in the information and communication technologies (ICT) have raised new opportunities for the implementation of novel applications and the pro- sion of high-quality services over global networks. The aim is to utilize this 'infor- tion society era' for improving the quality of life for all citizens, disseminating knowledge, strengthening social cohesion, generating earnings and finally ensuring that organizations and public bodies remain competitive in the global electronic m- ketplace. Unfortunately, such a rapid technological evolution cannot be problem free. Concerns are raised regarding the 'lack of trust' in electronic procedures and the - tent to which 'information security' and 'user privacy' can be ensured. TrustBus 2009 brought together academic researchers and industry developers, who discussed the state of the art in technology for establishing trust, privacy and security in digital business. We thank the attendees for coming to Linz to participate and debate the new emerging advances in this area.