This book constitutes the refereed proceedings of the 35th IFIP TC 11 International Conference on Information Security and Privacy Protection, SEC 2020, held in Maribor, Slovenia, in September 2020. The conference was held virtually due to the COVID-19 pandemic. The 29 full papers presented were carefully reviewed and selected from 149 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 channel attacks; connection security; human aspects of security and privacy; detecting malware and software weaknesses; system security; network security and privacy; access control and authentication; crypto currencies; privacy and security management; and machine learning and security.