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See detail"Just for the sake of transparency": Exploring Voter Mental Models Of Verifiability
Zollinger, Marie-Laure UL; Estaji, Ehsan UL; Ryan, Peter Y A UL et al

in Electronic Voting, Sixth International Joint Conference, E-Vote-ID 2021, Bregenz, Austria, October 5-8 (2021, October)

Verifiable voting schemes allow voters to verify their individual votes and the election outcome. The voting protocol Selene offers verification of plaintext votes while preserving privacy. Misconceptions ... [more ▼]

Verifiable voting schemes allow voters to verify their individual votes and the election outcome. The voting protocol Selene offers verification of plaintext votes while preserving privacy. Misconceptions of verification mechanisms might result in voters mistrust of the system or abstaining from using it. In this paper, we interviewed 24 participants and invited them to illustrate their mental models of Selene. The drawings demonstrated different levels of sophistication and four mental models: 1) technology understanding, 2) meaning of the verification phase, 3) security concerns, and 4) unnecessary steps. We highlight the misconceptions expressed regarding Internet voting technologies and the system design. Based on our findings, we conclude with recommendations for future implementations of Selene as well as for the design of Internet voting systems in general. [less ▲]

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See detailShort paper: Mechanized Proofs of Verifiability and Privacy in a paper-based e-voting Scheme
Zollinger, Marie-Laure UL; Roenne, Peter UL; Ryan, Peter UL

in International Conference on Financial Crypto Workshop on Advances in Secure Electronic Voting (2020, February)

Detailed reference viewed: 86 (7 UL)
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See detailCoercion-Resistant Voting in Linear Time via Fully Homomorphic Encryption: Towards a Quantum-Safe Scheme
Roenne, Peter UL; Atashpendar, Arash UL; Kristian, Gjøsteen et al

in Financial Cryptography and Data Security 2019. FC 2019: International Workshops, CIW, VOTING, and WTSC (2020)

We present an approach for performing the tallying work in the coercion-resistant JCJ voting protocol, introduced by Juels, Catalano, and Jakobsson, in linear time using fully homomorphic encryption (FHE ... [more ▼]

We present an approach for performing the tallying work in the coercion-resistant JCJ voting protocol, introduced by Juels, Catalano, and Jakobsson, in linear time using fully homomorphic encryption (FHE). The suggested enhancement also paves the path towards making JCJ quantum-resistant, while leaving the underlying structure of JCJ intact. The pairwise comparison-based approach of JCJ using plaintext equivalence tests leads to a quadratic blow-up in the number of votes, which makes the tallying process rather impractical in realistic settings with a large number of voters. We show how the removal of invalid votes can be done in linear time via a solution based on recent advances in various FHE primitives such as hashing, zero-knowledge proofs of correct decryption, verifiable shuffles and threshold FHE. We conclude by touching upon some of the advantages and challenges of such an approach, followed by a discussion of further security and post-quantum considerations. [less ▲]

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See detail(Universal) Unconditional Verifiability in E-Voting without Trusted Parties
Iovino, Vincenzo; Rial, Alfredo UL; Roenne, Peter UL et al

in 2020 IEEE 33rd Computer Security Foundations Symposium (2020)

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See detailTowards Model Checking of Voting Protocols in Uppaal
Jamroga, Wojciech UL; Kim, Yan UL; Kurpiewski, Damian et al

in Proceedings of the Fifth International Joint Conference on Electronic Voting E-VOTE-ID 2020 (2020)

The design and implementation of a trustworthy e-voting system is a challenging task. Formal analysis can be of great help here. In particular, it can lead to a better understanding of how the voting ... [more ▼]

The design and implementation of a trustworthy e-voting system is a challenging task. Formal analysis can be of great help here. In particular, it can lead to a better understanding of how the voting system works, and what requirements on the system are relevant. In this paper, we propose that the state-of-art model checker Uppaal provides a good environment for modelling and preliminary verification of voting protocols. To illustrate this, we demonstrate how to model a version of Pret-a-Voter in Uppaal, together with some natural extensions. We also show how to verify a variant of receipt-freeness, despite the severe limitations of the property specification language in the model checker. The aim of this work is to open a new path, rather then deliver the ultimate outcome of formal analysis. A comprehensive model of Pret-a-Voter, more accurate specification of requirements, and exhaustive verification are planned for the future. [less ▲]

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See detailVerifiable Inner Product Encryption Scheme
Soroush, Najmeh UL; Iovino, Vincenzo; Rial, Alfredo UL et al

in Public-Key Cryptography – PKC 2020 (2020)

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See detailPost-Quantum Anonymous Veto Networks
Ding, Jintai; Emery, Doug; Mueller, Johannes UL et al

in E-Vote-ID 2020 (2020)

Detailed reference viewed: 63 (4 UL)
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See detailRevisiting Practical and Usable Coercion-Resistant Remote E-Voting
Estaji, Ehsan UL; Haines, Thomas; Gjoesteen, Kristian et al

in Electronic Voting - 5th International Joint Conference, E-Vote-ID 2020, Bregenz, Austria, October 6-9, 2020, Proceedings (2020)

Detailed reference viewed: 107 (8 UL)
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See detailPreservation of DNA Privacy During the Large Scale Detection of COVID-19
Hollenstein, Marcel; Naccache, David; Roenne, Peter UL et al

E-print/Working paper (2020)

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See detailA Lightweight Implementation of NTRU Prime for the Post-Quantum Internet of Things
Cheng, Hao UL; Dinu, Dumitru-Daniel; Groszschädl, Johann UL et al

in Laurent, Maryline; Giannetsos, Thanassis (Eds.) Information Security Theory and Practice, 13th IFIP WG 11.2 International Conference, WISTP 2019, Paris, France, December 11–12, 2019, Proceedings (2019, December)

The dawning era of quantum computing has initiated various initiatives for the standardization of post-quantum cryptosystems with the goal of (eventually) replacing RSA and ECC. NTRU Prime is a variant of ... [more ▼]

The dawning era of quantum computing has initiated various initiatives for the standardization of post-quantum cryptosystems with the goal of (eventually) replacing RSA and ECC. NTRU Prime is a variant of the classical NTRU cryptosystem that comes with a couple of tweaks to minimize the attack surface; most notably, it avoids rings with "worrisome" structure. This paper presents, to our knowledge, the first assembler-optimized implementation of Streamlined NTRU Prime for an 8-bit AVR microcontroller and shows that high-security lattice-based cryptography is feasible for small IoT devices. An encapsulation operation using parameters for 128-bit post-quantum security requires 8.2 million clock cycles when executed on an 8-bit ATmega1284 microcontroller. The decapsulation is approximately twice as costly and has an execution time of 15.6 million cycles. We achieved this performance through (i) new low-level software optimization techniques to accelerate Karatsuba-based polynomial multiplication on the 8-bit AVR platform and (ii) an efficient implementation of the coefficient modular reduction written in assembly language. The execution time of encapsulation and decapsulation is independent of secret data, which makes our software resistant against timing attacks. Finally, we assess the performance one could theoretically gain by using a so-called product-form polynomial as part of the secret key and discuss potential security implications. [less ▲]

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See detailAuthenticated Key Distribution: When the Coupon Collector is Your Enemy
Beunardeau, Marc; El Orche, Fatima Ezzahra UL; Maimut, Diana et al

in Innovative Security Solutions for Information Technology and Communications (2019, November 14)

We introduce new authenticated key exchange protocols which on the one hand do not resort to standard public key setups with corresponding assumptions of computationally hard problems, but on the other ... [more ▼]

We introduce new authenticated key exchange protocols which on the one hand do not resort to standard public key setups with corresponding assumptions of computationally hard problems, but on the other hand, are more efficient than distributing symmetric keys among the participants. To this end, we rely on a trusted central authority distributing key material whose size is independent of the total number of users, and which allows the users to obtain shared secret keys. We analyze the security of our construction, taking into account various attack models. Importantly, only symmetric primitives are needed in the protocol making it an alternative to quantum-safe key exchange protocols which rely on hardness assumptions. [less ▲]

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See detailUser Experience Design for E-Voting: How mental models align with security mechanisms
Zollinger, Marie-Laure UL; Distler, Verena UL; Roenne, Peter UL et al

in Electronic Voting (2019, October)

This paper presents a mobile application for vote-casting and vote-verification based on the Selene e-voting protocol and explains how it was developed and implemented using the User Experience Design ... [more ▼]

This paper presents a mobile application for vote-casting and vote-verification based on the Selene e-voting protocol and explains how it was developed and implemented using the User Experience Design process. The resulting interface was tested with 38 participants, and user experience data was collected via questionnaires and semi-structured interviews on user experience and perceived security. Results concerning the impact of displaying security mechanisms on UX were presented in a complementary paper. Here we expand on this analysis by studying the mental models revealed during the interviews and compare them with theoretical security notions. Finally, we propose a list of improvements for designs of future voting protocols. [less ▲]

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See detailA Lightweight Implementation of NTRUEncrypt for 8-bit AVR Microcontrollers
Cheng, Hao UL; Groszschädl, Johann UL; Roenne, Peter UL et al

E-print/Working paper (2019)

Introduced in 1996, NTRUEncrypt is not only one of the earliest but also one of the most scrutinized lattice-based cryptosystems and a serious contender in NIST’s ongoing Post-Quantum Cryptography (PQC ... [more ▼]

Introduced in 1996, NTRUEncrypt is not only one of the earliest but also one of the most scrutinized lattice-based cryptosystems and a serious contender in NIST’s ongoing Post-Quantum Cryptography (PQC) standardization project. An important criterion for the assessment of candidates is their computational cost in various hardware and software environments. This paper contributes to the evaluation of NTRUEncrypt on the ATmega class of AVR microcontrollers, which belongs to the most popular 8-bit platforms in the embedded domain. More concretely, we present AvrNtru, a carefully-optimized implementation of NTRUEncrypt that we developed from scratch with the goal of achieving high performance and resistance to timing attacks. AvrNtru complies with version 3.3 of the EESS#1 specification and supports recent product-form parameter sets like ees443ep1, ees587ep1, and ees743ep1. A full encryption operation (including mask generation and blinding- polynomial generation) using the ees443ep1 parameters takes 834,272 clock cycles on an ATmega1281 microcontroller; the decryption is slightly more costly and has an execution time of 1,061,683 cycles. When choosing the ees743ep1 parameters to achieve a 256-bit security level, 1,539,829 clock cycles are cost for encryption and 2,103,228 clock cycles for decryption. We achieved these results thanks to a novel hybrid technique for multiplication in truncated polynomial rings where one of the operands is a sparse ternary polynomial in product form. Our hybrid technique is inspired by Gura et al’s hybrid method for multiple-precision integer multiplication (CHES 2004) and takes advantage of the large register file of the AVR architecture to minimize the number of load instructions. A constant-time multiplication in the ring specified by the ees443ep1 parameters requires only 210,827 cycles, which sets a new speed record for the arithmetic component of a lattice-based cryptosystem on an 8-bit microcontroller. [less ▲]

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See detailA Critical Security Analysis of the Password-Based Authentication Honeywords System Under Code-Corruption Attack
Genç, Ziya Alper UL; Lenzini, Gabriele UL; Ryan, Peter UL et al

in Information Systems Security and Privacy (2019, July)

Password-based authentication is a widespread method to access into systems, thus password files are a valuable resource often target of attacks. To detect when a password file has been stolen, Juels and ... [more ▼]

Password-based authentication is a widespread method to access into systems, thus password files are a valuable resource often target of attacks. To detect when a password file has been stolen, Juels and Rivest introduced the Honeywords System in 2013. The core idea is to store the password with a list of decoy words that are ``indistinguishable'' from the password, called honeywords. An adversary that obtains the password file and, by dictionary attack, retrieves the honeywords can only guess the password when attempting to log in: but any incorrect guess will set off an alarm, warning that file has been compromised. In a recent conference paper, we studied the security of the Honeywords System in a scenario where the intruder also manages to corrupt the server's code (with certain limiting assumptions); we proposed an authentication protocol and proved it secure despite the corruption. In this extended journal version, we detail the analysis and we extend it, under the same attacker model, to the other two protocols of the original Honeywords System, the setup and change of password. We formally verify the security of both of them; further, we discuss that our design suggests a completely new approach that diverges from the original idea of the Honeywords System but indicates an alternative way to authenticate users which is robust to server's code-corruption. [less ▲]

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See detailSecurity – Visible, Yet Unseen? How Displaying Security Mechanisms Impacts User Experience and Perceived Security
Distler, Verena UL; Zollinger, Marie-Laure UL; Lallemand, Carine UL et al

in Proceedings of ACM CHI Conference on Human Factors in Computing Systems (CHI2019) (2019, April)

An unsolved debate in the field of usable security concerns whether security mechanisms should be visible, or blackboxed away from the user for the sake of usability. However, tying this question to ... [more ▼]

An unsolved debate in the field of usable security concerns whether security mechanisms should be visible, or blackboxed away from the user for the sake of usability. However, tying this question to pragmatic usability factors only might be simplistic. This study aims at researching the impact of displaying security mechanisms on user experience (UX) in the context of e-voting. Two versions of an e-voting application were designed and tested using a between-group experimental protocol (N=38). Version D displayed security mechanisms, while version ND did not reveal any security-related information. We collected data on UX using standardised evaluation scales and semi-structured interviews. Version D performed better overall in terms of UX and need fulfilment. Qualitative analysis of the interviews gives further insights into factors impacting perceived security. Our study adds to existing research suggesting a conceptual shift from usability to UX and discusses implications for designing and evaluating secure systems. [less ▲]

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See detailHow to Assess the Usability Metrics of E-Voting Schemes
Marky, Karola; Zollinger, Marie-Laure UL; Funk, Markus et al

in Lecture Notes in Computer Science (2019, February)

Detailed reference viewed: 158 (20 UL)
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See detailNoCry: No More Secure Encryption Keys for Cryptographic Ransomware
Genç, Ziya Alper UL; Lenzini, Gabriele UL; Ryan, Peter UL

in Proceedings of the Second International Workshop on Emerging Technologies for Authorization and Authentication (2019)

Since the appearance of ransomware in the cyber crime scene, researchers and anti-malware companies have been offering solutions to mitigate the threat. Anti-malware solutions differ on the specific ... [more ▼]

Since the appearance of ransomware in the cyber crime scene, researchers and anti-malware companies have been offering solutions to mitigate the threat. Anti-malware solutions differ on the specific strategy they implement, and all have pros and cons. However, three requirements concern them all: their implementation must be secure, be effective, and be efficient. Recently, Genç et al. proposed to stop a specific class of ransomware, the cryptographically strong one, by blocking unauthorized calls to cryptographically secure pseudo-random number generators, which are required to build strong encryption keys. Here, in adherence to the requirements, we discuss an implementation of that solution that is more secure (with components that are not vulnerable to known attacks), more effective (with less false negatives in the class of ransomware addressed) and more efficient (with minimal false positive rate and negligible overhead) than the original, bringing its security and technological readiness to a higher level. [less ▲]

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See detailAn offline dictionary attack against zkPAKE protocol
Lopez Becerra, José Miguel UL; Ryan, Peter UL; Sala, Petra UL et al

in An offline dictionary attack against zkPAKE protocol (2019)

Password Authenticated Key Exchange (PAKE) allows a user to establish a secure cryptographic key with a server, using only knowledge of a pre-shared password. One of the basic security require- ments of ... [more ▼]

Password Authenticated Key Exchange (PAKE) allows a user to establish a secure cryptographic key with a server, using only knowledge of a pre-shared password. One of the basic security require- ments of PAKE is to prevent o ine dictionary attacks. In this paper, we revisit zkPAKE, an augmented PAKE that has been recently proposed by Mochetti, Resende, and Aranha (SBSeg 2015). Our work shows that the zkPAKE protocol is prone to o ine password guess- ing attack, even in the presence of an adversary that has only eavesdrop- ping capabilities. Results of performance evaluation show that our attack is practical and e cient.Therefore, zkPAKE is insecure and should not be used as a password-authenticated key exchange mechanism. [less ▲]

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See detailRisk-Limiting Tallies
Jamroga, Wojciech UL; Roenne, Peter UL; Ryan, Peter UL et al

in Electronic Voting: Proceedings of E-Vote-ID (2019)

Detailed reference viewed: 38 (5 UL)