This book constitutes the refereed proceedings of the 34th IFIP TC 11 International Conference on Information Security and Privacy Protection, SEC 2019, held in Lisbon, Portugal, in June 2019.The 26 revised full papers presented were carefully reviewed and selected from 76 submissions. The papers present novel research on theoretical and practical aspects of security and privacy protection in ICT systems. They are organized in topical sections on intrusion detection, access control, organizational and behavioral, crypto and encryption, and integrity.