Malware and attacks -- Persistence in Linux-Based IoT Malware -- Real-time triggering of Android memory dumps for stealthy attack investigation -- Using Features of Encrypted Network Traffic to Detect Malware -- Formal analysis -- Machine-checking the universal verifiability of ElectionGuard -- Information-Flow Control by means of Security Wrappers for Active Object Languages with Futures -- Efficient mixing of arbitrary ballots with everlasting privacy: How to verifiably mix the PPATC scheme -- Applied cryptography -- (F)unctional Sifting: A Privacy-Preserving Reputation System Through Multi-Input Functional Encryption -- TLV-to-MUC Express: Post-quantum MACsec in VXLAN -- On the Certi cate Revocation Problem in the Maritime Sector -- Security mechanisms and training -- HoneyHash: Honeyword Generation Based on Transformed Hashes -- Agent-based File Extraction Using Virtual Machine Introspection -- Cyber range automation overview with a case study of CRATE -- Applications and privacy -- Privacy Analysis of COVID-19 Contact Tracing Apps in the EU -- OnLITE: On-line Label for IoT Transparency Enhancement -- An Investigation of Comic-Based Permission Requests.

This book constitutes the refereed proceedings of the 25th Nordic Conference on Secure IT Systems, NordSec 2020, which was organized by Linköping University, Sweden, and held online during November 23-24, 2020. The 15 papers presented in this volume were carefully reviewed and selected from 45 submissions. They were organized in topical sections named: malware and attacks; formal analysis; applied cryptography; security mechanisms and training; and applications and privacy.