Secure IT Systems: 26th Nordic Conference, NordSec 2021, Virtual Event, November 29–30, 2021, Proceedings (Security and Cryptology)

Preface
Organization
Contents
Applied Cryptography
Communicating Through Subliminal-Free Signatures
	1 Introduction
	2 Preliminaries
		2.1 Simmons' Signing Protocol
	3 Novel Fail-Stop and Cuckoo's Channels
		3.1 Zhang et al.'s Signing Protocol
		3.2 Dong et al.'s Signing Protocol
	4 Conclusions
	References
Size, Speed, and Security: An Ed25519 Case Study
	1 Introduction
	2 Background
		2.1 EdDSA
		2.2 Ed25519
		2.3 Ed25519 Implementations
		2.4 Related Work
	3 When Optimization Goes Wrong
	4 Computer-Aided Ed25519
		4.1 Benchmarking
	5 Conclusion
	References
Arrows in a Quiver: A Secure Certificateless Group Key Distribution Protocol for Drones
	1 Introduction
	2 Related Work
	3 System Model
	4 Arrows in a Quiver (AinQ)
		4.1 AinQ Scheme
		4.2 AinQ Protocol
	5 Security Analysis
		5.1 Security Proof
	6 Experiments
		6.1 Performance of Core Cryptographic Functions
	7 Conclusion
	References
Security in Internet of Things
X-Pro: Distributed XDP Proxies Against Botnets of Things
	1 Introduction
	2 Related Work
	3 XDP and BPF Maps
	4 The X-Pro Solution
		4.1 Overall Architecture and Solution
		4.2 Filtering Design
		4.3 Synchronization Design
		4.4 Proxy Design Based on XDP
		4.5 Device Side Design
	5 Implementation
		5.1 Proxy
		5.2 Centralized Database
		5.3 IoT Units
	6 Experimental Evaluation
		6.1 Single-Proxy
		6.2 Multiple-Proxy Working Together
		6.3 Overhead from the IoT Units
	7 Conclusion and Future Work
	A  Proxy Synchronization Protocol
	B  Packet Filtering Procedures
	References
Industrialising Blackmail: Privacy Invasion Based IoT Ransomware
	1 Introduction
	2 Background and Related Work
		2.1 IoT Based Ransomware
		2.2 Privacy Invasion
	3 Data Sources
	4 Identifying Private Data
		4.1 Malicious Use of Machine Learning
		4.2 Network-Based Privacy Invasion
		4.3 Data Processing
	5 Data Collation
		5.1 Data Management
		5.2 The Ransom
		5.3 Publishing Private Information
		5.4 Scale of Operation
	6 Proof of Concepts
		6.1 Netgear R6250 Router
		6.2 Yealink SIP-T38g Phone
		6.3 DCS-932L Camera
		6.4 Summary
	7 Discussion
		7.1 Countermeasures
		7.2 Limitations and Further Work
	8 Conclusions
	A  Appendices
		A.1  Data Collator Structure
		A.2  Collator and Ransom Note
	References
Machine Learning and Security
SQL Injections and Reinforcement Learning: An Empirical Evaluation of the Role of Action Structure
	1 Introduction
	2 Background
		2.1 Reinforcement Learning
		2.2 Word Level RL
		2.3 Penetration Testing
	3 Related Work
	4 Methods
		4.1 Environment
		4.2 Structured Agent
		4.3 Structureless Agent
	5 Experiments
		5.1 Reference Agents
		5.2 Structured Agent
		5.3 Structureless Agent
	6 Ethical Considerations
	7 Future Work and Conclusions
	A  Implementation Details
		A.1  Structured Agent
		A.2  Structureless Agent
	References
Secure Collaborative Learning for Predictive Maintenance in Optical Networks
	1 Introduction
	2 Background
	3 Framework
		3.1 Secure Aggregation Protocol
		3.2 Training Procedure
	4 Experiments
		4.1 Description of Use Case
		4.2 Data Generation and Preprocessing
		4.3 Local Models
		4.4 Global Model
		4.5 Performance Evaluation Metrics
	5 Analysis
	6 Conclusion
	References
Network Security
Gollector: Measuring Domain Name Dark Matter from Different Vantage Points
	1 Introduction
	2 Background
	3 Related Work
	4 Vantage Points
	5 Design
		5.1 Architecture
		5.2 Collectors
	6 Dataset
	7 Use Cases
		7.1 Early Detection of Domain Names
		7.2 Split Horizon and Data Leakage
		7.3 Subdomain Enumeration
	8 Conclusions
	A  Clique Cover Algorithm
	B  Examples of Cliques
	References
Adversarial Trends in Mobile Communication Systems: From Attack Patterns to Potential Defenses Strategies
	1 Introduction
	2 Background
		2.1 Mobile Network Topology
		2.2 Security Weaknesses
		2.3 Bhadra Framework
		2.4 Attack Pattern and Graph Analysis
	3 Methodology
		3.1 Attack Collection and Sampling
		3.2 Attack Modeling
		3.3 Graph Analysis
	4 Results
		4.1 Common Attack Patterns
		4.2 Loss of Connectivity
		4.3 Unique Paths
	5 Discussion
	6 Conclusion
	References
Trust
Trusted Sockets Layer: A TLS 1.3 Based Trusted Channel Protocol
	1 Introduction
	2 Background
		2.1 Transport Layer Security
		2.2 Trusted Computing
		2.3 Attestation
		2.4 Channel Binding
	3 Survey: Combining TLS and Attestation
		3.1 Design Considerations
		3.2 Proposals with Pre-handshake Attestation
		3.3 Proposals with Intra-handshake Attestation
		3.4 Proposals with Post-handshake Attestation
		3.5 Summary and Conclusions
	4 Trusted Sockets Layer Protocol
		4.1 Requirements
		4.2 Threat Model
		4.3 Design
		4.4 Protocol Flow
		4.5 Implementation
		4.6 Security Analysis
	5 Conclusions and Further Work
	References
Preliminary Security Analysis, Formalisation, and Verification of OpenTitan Secure Boot Code
	1 Introduction
	2 OpenTitan
		2.1 Hardware Components
	3 Security Analysis
		3.1 Security Policies and Goals
	4 Potential Vulnerability in HMAC Wipe
		4.1 Brute Forcing Wipe Values
	5 Formalisation and Verification in CBMC
		5.1 Wipe Attack in CBMC
		5.2 Modelling and Verification of Security Goals
		5.3 Results of CBMC Verification
	6 Formalisation and Verification in UPPAAL
		6.1 Wipe Attack in UPPAAL
		6.2 Results of UPPAAL Verification
	7 Summary Results and Evaluation
	8 Conclusion
	1  Security Properties
		1.1  Goal G1
		1.2  Goal G10/G11/G12
	2  UPPAAL Queries for G1
	References
Author Index