@misc{MitsevaPanchenko, author = {Mitseva, Asya and Panchenko, Andriy}, title = {Stop, don't click here anymore: boosting website fingerprinting by considering sets of subpages}, series = {Proceedings of the 33rd USENIX Security Symposium (USENIX Sec 2024), Philadelphia, PA, USA, August 14-16, 2024}, journal = {Proceedings of the 33rd USENIX Security Symposium (USENIX Sec 2024), Philadelphia, PA, USA, August 14-16, 2024}, isbn = {978-1-939133-44-1}, pages = {4139 -- 4156}, abstract = {A type of traffic analysis, website fingerprinting (WFP), aims to reveal the website a user visits over an encrypted and anonymized connection by observing and analyzing data flow patterns. Its efficiency against anonymization networks such as Tor has been widely studied, resulting in methods that have steadily increased in both complexity and power. While modern WFP attacks have proven to be highly accurate in laboratory settings, their real-world feasibility is highly debated. These attacks also exclude valuable information by ignoring typical user browsing behavior: users often visit multiple pages of a single website sequentially, e.g., by following links. In this paper, we aim to provide a more realistic assessment of the degree to which Tor users are exposed to WFP. We propose both a novel WFP attack and efficient strategies for adapting existing methods to account for sequential visits of pages within a website. While existing WFP attacks fail to detect almost any website in real-world settings, our novel methods achieve F1-scores of 1.0 for more than half of the target websites. Our attacks remain robust against state-of- the-art WFP defenses, achieving 2.5 to 5 times the accuracy of prior work, and in some cases even rendering the defenses useless. Our methods enable to estimate and to communicate to the user the risk of successive page visits within a website (even in the presence of noise pages) to stop before the WFP attack reaches a critical level of confidence.}, language = {en} } @misc{GiustolisiSheikhi‐Garjan, author = {Giustolisi, Rosario and Sheikhi-Garjan, Maryam}, title = {Efficient cleansing in coercion-resistant voting}, series = {Electronic Voting : 9th International Joint Conference, E-Vote-ID 2024, Tarragona, Spain, October 2-4, 2024, Proceedings}, journal = {Electronic Voting : 9th International Joint Conference, E-Vote-ID 2024, Tarragona, Spain, October 2-4, 2024, Proceedings}, publisher = {Springer, Cham}, isbn = {978-3-031-72243-1}, doi = {10.1007/978-3-031-72244-8_5}, pages = {72 -- 88}, abstract = {Coercion resistance is a strong security property of electronic voting that prevents adversaries from forcing voters to vote in a specific way by using threats or rewards. There exist clever techniques aimed at preventing voter coercion based on fake credentials, but they are either inefficient or cannot support features such as revoting without leaking more information than necessary to coercers. One of the reasons is that invalid ballots cast due to revoting or coercion need to be removed before the tallying. In this paper, we propose a coercion-resistant Internet voting scheme that does not require the removal of invalid ballots, hence avoids the leakage of information, but still supports revoting. The scheme is very efficient and achieves linear tallying.}, language = {en} } @misc{HainesMosahebMuelleretal., author = {Haines, Thomas and Mosaheb, Rafieh and M{\"u}ller, Johannes and Pryvalov, Ivan}, title = {SoK: Secure E-Voting with Everlasting Privacy.}, series = {Thomas Haines, Rafieh Mosaheb, Johannes M{\"u}ller, Ivan Pryvalov. "SoK: Secure E-Voting with Everlasting Privacy." In Proceedings on Privacy Enhancing Technologies (PoPETS), 2023.}, journal = {Thomas Haines, Rafieh Mosaheb, Johannes M{\"u}ller, Ivan Pryvalov. "SoK: Secure E-Voting with Everlasting Privacy." In Proceedings on Privacy Enhancing Technologies (PoPETS), 2023.}, doi = {10.56553/popets-2023-0017}, pages = {279 -- 293}, abstract = {Vote privacy is a fundamental right, which needs to be protected not only during an election, or for a limited time afterwards, but for the foreseeable future. Numerous electronic voting (e-voting) protocols have been proposed to address this challenge, striving for everlasting privacy. This property guarantees that even computationally unbounded adversaries cannot break privacy of past elections. The broad interest in secure e-voting with everlasting privacy has spawned a large variety of protocols over the last three decades. These protocols differ in many aspects, in particular the precise security properties they aim for, the threat scenarios they consider, and the privacy-preserving techniques they employ. Unfortunately, these differences are often opaque, making analysis and comparison cumbersome. In order to overcome this non-transparent state of affairs, we systematically analyze all e-voting protocols designed to provide everlasting privacy. First, we illustrate the relations and dependencies between all these different protocols. Next, we analyze in depth which protocols do provide secure and efficient approaches to e-voting with everlasting privacy under realistic assumptions, and which ones do not. Eventually, based on our extensive and detailed treatment, we identify which research problems in this field have already been solved, and which ones are still open. Altogether, our work offers a well - founded reference point for conducting research on secure e - voting with everlasting privacy as well as for future - proofing privacy in real - world electronic elections.}, language = {en} } @misc{BackesBerrangHanzliketal., author = {Backes, Michael and Berrang, Pascal and Hanzlik, Lucjan and Pryvalov, Ivan}, title = {A Framework for Constructing Single Secret Leader Election from MPC.}, series = {Michael Backes, Pascal Berrang, Lucjan Hanzlik, Ivan Pryvalov. "A Framework for Constructing Single Secret Leader Election from MPC." In Computer Security - ESORICS 2022 - 27th European Symposium on Research in Computer Security, Copenhagen, Denmark, September 26-30, 2022, Proceedings, Part II, pp.672-691, Springer.}, journal = {Michael Backes, Pascal Berrang, Lucjan Hanzlik, Ivan Pryvalov. "A Framework for Constructing Single Secret Leader Election from MPC." In Computer Security - ESORICS 2022 - 27th European Symposium on Research in Computer Security, Copenhagen, Denmark, September 26-30, 2022, Proceedings, Part II, pp.672-691, Springer.}, publisher = {Springer}, doi = {10.1007/978-3-031-17146-8_33}, pages = {672 -- 691}, abstract = {The emergence of distributed digital currencies has raised the need for a reliable consensus mechanism. In proof-of-stake cryptocurrencies, the participants periodically choose a closed set of validators, who can vote and append transactions to the blockchain. Each validator can become a leader with the probability proportional to its stake. Keeping the leader private yet unique until it publishes a new block can significantly reduce the attack vector of an adversary and improve the throughput of the network. The problem of Single Secret Leader Election (SSLE) was first formally defined by Boneh et al. in 2020. In this work, we propose a novel framework for constructing SSLE protocols, which relies on secure multi-party computation (MPC) and satisfies the desired security properties. Our framework does not use any shuffle or sort operations and has a computational cost for N parties as low as O(N) of basic MPC operations per party. We improve the stateof-the-art for SSLE protocols that do not assume a trusted setup. Moreover, our SSLE scheme efficiently handles weighted elections. That is, for a total weight S of N parties, the associated costs are only increased by a factor of log S. When the MPC layer is instantiated with techniques based on Shamir's secret-sharing, our SSLE has a communication cost of O(N2) which is spread over O(logN) rounds, can tolerate up to t < N/2 of faulty nodes without restarting the protocol, and its security relies on DDH in the random oracle model. When the MPC layer is instantiated with more efficient techniques based on garbled circuits, our SSLE requires all parties to participate, up to N -1 of which can be malicious, and its security is based on the random oracle model.}, language = {en} } @misc{BackesHanzlikHerzbergetal., author = {Backes, Michael and Hanzlik, Lucjan and Herzberg, Amir and Kate, Aniket and Pryvalov, Ivan}, title = {Efficient Non-Interactive Zero-Knowledge Proofs in Cross-Domains Without Trusted Setup.}, series = {Public-Key Cryptography - PKC 2019 : 22nd IACR International Conference on Practice and Theory of Public-Key Cryptography, Beijing, China, April 14-17, 2019, Proceedings, Part I}, journal = {Public-Key Cryptography - PKC 2019 : 22nd IACR International Conference on Practice and Theory of Public-Key Cryptography, Beijing, China, April 14-17, 2019, Proceedings, Part I}, editor = {Lin, Dongdai}, publisher = {Springer}, doi = {10.1007/978-3-030-17253-4_10}, pages = {286 -- 313}, abstract = {With the recent emergence of efficient zero-knowledge (ZK) proofs for general circuits, while efficient zero-knowledge proofs of algebraic statements have existed for decades, a natural challenge arose to combine algebraic and non-algebraic statements. Chase et al. (CRYPTO 2016) proposed an interactive ZK proof system for this cross-domain problem. As a use case they show that their system can be used to prove knowledge of a RSA/DSA signature on a message m with respect to a publicly known Pedersen commitment gmhr. One drawback of their system is that it requires interaction between the prover and the verifier. This is due to the interactive nature of garbled circuits, which are used in their construction. Subsequently, Agrawal et al. (CRYPTO 2018) proposed an efficient non-interactive ZK (NIZK) proof system fo cross-domains based on SNARKs, which however require a trusted setup assumption. In this paper, we propose a NIZK proof system for cross domains that requires no trusted setup and is efficient both for the prover and the verifier. Our system constitutes a combination of Schnorr based ZK proofs and ZK proofs for general circuits by Giacomelli et al. (USENIX 2016). The proof size and the running time of our system are comparable to the approach by Chase et al. Compared to Bulletproofs (SP 2018), a recent NIZK proofs system on committed inputs, our techniques achieve asymptotically better performance on prover and verifier, thus presenting a different trade-off between the proof size and the running time.}, language = {en} } @misc{BackesHerzbergKateetal., author = {Backes, Michael and Herzberg, Amir and Kate, Aniket and Pryvalov, Ivan}, title = {Differentially private data aggregation with optimal utility}, series = {Proceedings of the 30th Annual Computer Security Applications Conference, ACSAC 2014, New Orleans, LA, USA, December 8-12, 2014}, journal = {Proceedings of the 30th Annual Computer Security Applications Conference, ACSAC 2014, New Orleans, LA, USA, December 8-12, 2014}, publisher = {Springer}, doi = {10.1145/2664243.2664263}, pages = {316 -- 325}, abstract = {We define the concept of and present provably secure constructions for Anonymous RAM (AnonRAM), a novel multi-user storage primitive that offers strong privacy and integrity guarantees. AnonRAM combines privacy features of anonymous communication and oblivious RAM (ORAM) schemes, allowing it to protect, simultaneously, the privacy of content, access patterns and user's identity, from curious servers and from other (even adversarial) users. AnonRAM further protects integrity, i.e., it prevents malicious users from corrupting data of other users. We present two secure AnonRAM schemes, differing in design and time complexity. The first scheme has a simpler design; like efficient ORAM schemes, its time complexity is poly-logarithmic in the number of cells (per user); however, it is linear in the number of users. The second AnonRAM scheme reduces the overall complexity to poly-logarithmic in the total number of cells (of all users) at the cost of requiring two (non-colluding) servers.}, language = {en} } @misc{GajekLewandowsky, author = {Gajek, Sebastian and Lewandowsky, Marco}, title = {Trustless, Censorship-Resilient and Scalable Votings in the Permission-Based Blockchain Model}, series = {Euro-Par 2020 International Workshops, Warsaw, Poland, August 24-25, 2020, Revised Selected Papers}, journal = {Euro-Par 2020 International Workshops, Warsaw, Poland, August 24-25, 2020, Revised Selected Papers}, publisher = {Springer}, isbn = {978-3-030-71592-2}, doi = {10.1007/978-3-030-71593-9_5}, pages = {54 -- 65}, abstract = {Voting systems are the tool of choice when it comes to settle an agreement of different opinions. We propose a solution for a trustless, censorship-resilient and scalable electronic voting platform. By leveraging the blockchain together with the functional encryption paradigm, we fully decentralize the system and reduce the risks that a voting provider, like a corrupt government, does censor or manipulate the outcome.}, language = {en} } @misc{KharrufaAlKashoashAlNidawietal., author = {Kharrufa, Harith and Al-Kashoash, Hayder and Al-Nidawi, Yaarob and Quezada Mosquera, Maria Fernanda and Kemp, Andrew H.}, title = {Dynamic RPL for multi-hop routing in IoT applications}, series = {13th Annual Conference on Wireless On-demand Network Systems and Services (WONS)}, journal = {13th Annual Conference on Wireless On-demand Network Systems and Services (WONS)}, publisher = {IEEE}, isbn = {978-3-901882-88-3}, doi = {10.1109/WONS.2017.7888753}, pages = {4}, abstract = {The Routing Protocol for Low Power and Lossy Networks (RPL) has become the standard routing protocol for the Internet of Things (IoT). This paper investigates the use of RPL in dynamic networks and presents an enhanced RPL for different applications with dynamic mobility and diverse network requirements. This implementation of RPL is designed with a new dynamic Objective-Function (D-OF) to improve the Packet Delivery Ratio (PDR), end-to-end delay and energy consumption while maintaining low packet overhead and loop-avoidance. We propose a controlled reverse-trickle timer based on received signal strength identification (RSSI) readings to maintain high responsiveness with minimum overhead and consult the objective function when a movement or an inconsistency is detected to help nodes make an informed decision. Simulations are done using Cooja with random waypoint mobility scenario for healthcare applications considering multi-hop routing. The results show that the proposed dynamic RPL (D-RPL) adapts to the nodes mobility and has a higher PDR, slightly lower end-to-end delay and reasonable energy consumption compared to related existing protocols.}, language = {en} } @misc{MuellerPejoPryvalov, author = {M{\"u}ller, Johannes and Pej{\´o}, Bal{\´a}zs and Pryvalov, Ivan}, title = {DeVoS: Deniable Yet Verifiable Vote Updating}, series = {Proceedings on Privacy Enhancing Technologies}, journal = {Proceedings on Privacy Enhancing Technologies}, number = {1}, issn = {2299-0984}, doi = {10.56553/popets-2024-0021}, pages = {357 -- 378}, abstract = {Internet voting systems are supposed to meet the same high stan- dards as traditional paper-based systems when used in real political elections: freedom of choice, universal and equal suffrage, secrecy of the ballot, and independent verifiability of the election result. Although numerous Internet voting systems have been proposed to achieve these challenging goals simultaneously, few come close in reality. We propose a novel publicly verifiable and practically efficient Internet voting system, DeVoS, that advances the state of the art. The main feature of DeVoS is its ability to protect voters' freedom of choice in several dimensions. First, voters in DeVoS can intu- itively update their votes in a way that is deniable to observers but verifiable by the voters; in this way voters can secretly overwrite potentially coerced votes. Second, in addition to (basic) vote privacy, DeVoS also guarantees strong participation privacy by end-to-end hiding which voters have submitted ballots and which have not. Finally, DeVoS is fully compatible with Perfectly Private Audit Trail, a state-of-the-art Internet voting protocol with practical everlasting privacy. In combination, DeVoS offers a new way to secure free Internet elections with strong and long-term privacy properties.}, language = {en} } @misc{BartschGopeKavunetal., author = {Bartsch, Witali and Gope, Prosanta and Kavun, Elif and Millwood, Owen and Panchenko, Andriy and Pasikhani, Aryan and Polian, Ilia}, title = {Design Rationale for Symbiotically Secure Key Management Systems in IoT and Beyond}, series = {Proceedings of the 9th International Conference on Information Systems Security and Privacy ICISSP - Volume 1}, journal = {Proceedings of the 9th International Conference on Information Systems Security and Privacy ICISSP - Volume 1}, publisher = {SciTePress}, isbn = {978-989-758-624-8}, issn = {2184-4356}, doi = {10.5220/0011726900003405}, pages = {583 -- 591}, abstract = {The overwhelmingly widespread use of Internet of Things (IoT) in different application domains brought not only benefits, but, alas, security concerns as a result of the increased attack surface and vectors. One of the most critical mechanisms in IoT infrastructure is key management. This paper reflects on the problems and challenges of existing key management systems, starting with the discussion of a recent real-world attack. We identify and elaborate on the drawbacks of security primitives based purely on physical variations and - after highlighting the problems of such systems - continue on to deduce an effective and cost-efficient key management solution for IoT systems extending the symbiotic security approach in a previous work. The symbiotic architecture combines software, firmware, and hardware resources for secure IoT while avoiding the traditional scheme of static key storage and generating entropy for key material on-the-fly via a combination of a Physical Unclonable Func tion (PUF) and pseudo-random bits pre-populated in firmware.}, language = {en} } @misc{MitsevaThierseHoffmannetal., author = {Mitseva, Asya and Thierse, Paul and Hoffmann, Harald and Er, Devran and Panchenko, Andriy}, title = {Challenges and Pitfalls in Generating Representative ICS Datasets in Cyber Security Research}, series = {Computer Security, ESORICS 2022 International Workshops CyberICPS 2022, SECPRE 2022, SPOSE 2022, CPS4CIP 2022, CDT\&SECOMANE 2022, EIS 2022, and SecAssure 2022 Copenhagen, Denmark, September 26-30, 2022, Revised Selected Papers}, journal = {Computer Security, ESORICS 2022 International Workshops CyberICPS 2022, SECPRE 2022, SPOSE 2022, CPS4CIP 2022, CDT\&SECOMANE 2022, EIS 2022, and SecAssure 2022 Copenhagen, Denmark, September 26-30, 2022, Revised Selected Papers}, editor = {Katsikas, Sokratis}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-031-25459-8}, doi = {10.1007/978-3-031-25460-4_22}, pages = {379 -- 397}, language = {en} } @misc{GaoZhangChenetal., author = {Gao, Yunlong and Zhang, Yisong and Chen, Baihua and Xiong, Yuhui}, title = {Local Neighborhood Reliability Weighted Support Vector Machine}, series = {2020 2nd International Conference on Industrial Artificial Intelligence (IAI)}, journal = {2020 2nd International Conference on Industrial Artificial Intelligence (IAI)}, publisher = {IEEE}, isbn = {978-1-7281-8216-2}, doi = {10.1109/IAI50351.2020.9262215}, pages = {1 -- 6}, abstract = {Support vector machine (SVM) is a classification model, which learns the decision surface that maximizes the margin in the feature space. Such a decision surface has a good classification ability for unknown new samples. In real-world applications, the data set usually contains many noises and outliers, which will affect the learning of the decision surface, thus the maximum margin cannot be obtained, and the generalization ability of SVM will be reduced. In this paper, we introduce an adjacency factor to each input point to characterize the local neighbor relationship between each point. Weighting each sample point by the adjacency factor can let different sample points make different contributions to the learning of the decision surface. Thus, we can filter out the influence of noises and outliers on the decision surface by this weighting method. We propose this new method namely local neighborhood reliability weighted support vector machine (LN-SVM).}, language = {en} } @misc{Sheikhi‐GarjanGiustolisiSchuermann, author = {Sheikhi-Garjan, Maryam and Giustolisi, Rosario and Schuermann, Carsten}, title = {Receipt-Free Electronic Voting from zk-SNARK}, series = {Proceedings of the 20th International Conference on Security and Cryptography}, journal = {Proceedings of the 20th International Conference on Security and Cryptography}, publisher = {SCITEPRESS - Science and Technology Publications}, isbn = {978-989-758-666-8}, doi = {10.5220/0012140000003555}, pages = {254 -- 266}, language = {en} } @misc{MitsevaLewandowskyPanchenko, author = {Mitseva, Asya and Lewandowsky, Marco and Panchenko, Andriy}, title = {Whitelisting als Allheilmittel : {\"u}ber die Grenzen der Anomalieerkennung in industriellen Steuerungssystemen}, series = {Sicherheit 2026 : Sicherheit, Schutz und Zuverl{\"a}ssigkeit, 17.-19. M{\"a}rz 2026, Hamburg : proceedings}, journal = {Sicherheit 2026 : Sicherheit, Schutz und Zuverl{\"a}ssigkeit, 17.-19. M{\"a}rz 2026, Hamburg : proceedings}, editor = {Skwarek, Volker and W{\"o}hnert, Kai Hendrik and Kaven, Sascha and Wendzel, Steffen}, publisher = {Gesellschaft f{\"u}r Informatik}, address = {Bonn}, issn = {2944-7682}, doi = {10.18420/sicherheit2026_09}, pages = {103 -- 114}, abstract = {Die zunehmende Digitalisierung und Vernetzung industrieller Steuerungssysteme mit dem Internet macht diese anf{\"a}llig f{\"u}r Cyberangriffe. Ein zentraler Forschungsbereich konzentriert sich daher auf die Entwicklung reaktiver Sicherheitsmechanismen in Form industrieller Intrusion-Detection-Systeme (IIDS), die darauf ausgelegt sind, Anomalien im normalen Systembetrieb zu erkennen. Eine entscheidende Voraussetzung hierf{\"u}r ist die Identifizierung typischer Verkehrsmuster, die ausschließlich f{\"u}r das normale Verhalten industrieller Steuerungssysteme charakteristisch sind. Im Gegensatz zu fr{\"u}heren Arbeiten, die sich auf komplexe und protokollabh{\"a}ngige Modelle zur Charakterisierung des Netzwerkverkehrs industrieller Steuerungssysteme konzentrierten, schlagen wir in dieser Arbeit einfache, leicht umsetzbare und effektive Regeln vor, um zu ermitteln, ob der Netzwerkverkehr in Industrieanlagen - im Gegensatz zu herk{\"o}mmlichen IT-Netzwerken - {\"u}ber einen l{\"a}ngeren Zeitraum stabil bleibt. Anhand der Analyse mehrerer Datens{\"a}tze aus nachgebildeten und realen industriellen Steuerungssystemen mit unterschiedlichen industriellen Netzwerkprotokollen zeigen wir, dass aufbauend auf diesen Regeln bereits nach kurzer Beobachtungszeit hinreichend pr{\"a}gnante Muster extrahiert werden k{\"o}nnen, mit deren Hilfe es m{\"o}glich ist, g{\"a}ngige Verkehrsver{\"a}nderungen durch Netzverkehrsangriffe zu erkennen. Dieser Ansatz steht im Gegensatz zu herk{\"o}mmlichen Machine-Learning-IIDS, die h{\"a}ufig einen betr{\"a}chtlichen zeitlichen Aufwand f{\"u}r den Trainingsprozess erfordern. Somit stellen wir auch die Frage auf, inwieweit komplexe IIDS f{\"u}r den praktischen Betrieb tats{\"a}chlich unabdingbar sind.}, language = {de} }