This volume contains the papers presented at the 21st Annual IFIP WG 11.3 Conference on Data and Applications Security (DBSEC) held July 8 11 in - dondo Beach, California, USA. The purpose of the DBSEC conference is to disseminate original research results and experience reports in data and app- cations security. In response to the call for papers, 44 submissions were received. Following a rigorousreviewingprocess,18high-qualitypaperswereacceptedforpresentation and publication. In addition, two short papers were selected for poster pres- tation. The conference program also included one...