U radu je opisana, implementirana i ispitana metoda authentikacije temeljena na neinteraktivnim dokazima bez poznavanja. Takva metoda omogućuje primatelju da authenticira pošiljatelja i izračuna dijeljeni ključ. Način razmjene odnosno računanja zajedničkog ključa inspiriran je Diffie-Hellman protokolom. Metoda je implementirana u C++ programskom jeziku te ispitana na prijenosnom računalu i Raspberry Pi-u. Ispitana je i uspoređena brzina authentikacije. U odnosu na srodne authentikacijske sheme, postignute su usporedive brzine uz usporedivu razinu sigurnosti.
Kakuro is a popular logic puzzle, in which a player fills in all empty squares with digits from 1 to 9 so that the sum of digits in each (horizontal or vertical) line is equal to a given number, called a clue, and digits in each line are all different. In 2016, Bultel, Dreier, Dumas, and Lafourcade proposed a physical zero-knowledge proof protocol for Kakuro using a deck of cards; their proposed protocol enables a prover to convince a verifier that the prover knows the solution of a Kakuro puzzle without revealing any information about the solution. One possible drawback of their protocol would be that the protocol is not perfectly extractable, implying that a prover who does not know the solution can convince a verifier with a small probability; therefore, one has to repeat the protocol to make such an error become negligible. In this paper, to overcome this, we design zero-knowledge proof protocols for Kakuro having perfect extractability property. Our improvement relies on the ideas behind the copy protocols in the field of card-based cryptography. By executing our protocols with a real deck of physical playing cards, humans can practically perform an efficient zero-knowledge proof of knowledge for Kakuro.
Zero-knowledge proofs are cryptographic protocols where a prover convinces a verifier that a statement is true, without revealing why it is true or leaking any of the prover’s secret information. Since the introduction of zero-knowledge proofs, researchers have found numerous applications to other cryptographic schemes, such as electronic voting, group signatures, and verifiable computation. Zero-knowledge proofs have also become an integral part of blockchain-based cryptocurrencies. Thus, designing efficient zero-knowledge proofs is an important goal. Recently, the design space has become extremely large. To simplify protocol design, designers have begun to separate the process into modular steps. Information theoretic protocols are designed in idealised communication models and compiled into real protocols secure under cryptographic assumptions. In this thesis, we investigate the Ideal Linear Commitment model, which characterises interactive zero-knowledge protocols where the prover and verifier use homomorphic commitment schemes. We demonstrate the model’s power by exhibiting efficient protocols for useful tasks including NP-Complete problems and other more specialised problems. We demonstrate the model’s versatility by compiling the idealised protocols into real protocols under two completely different cryptographic assumptions; the discrete logarithm assumption, and the existence of collision-resistant hash functions. We show that the Ideal Linear Commitment model is a useful and effective abstraction for producing zero-knowledge protocols. Furthermore, by identifying the limitations of the model and finding protocols outside these constraints, we display special techniques which result in more efficient zero-knowledge proofs than ever. The results are novel and highly efficient protocols. Results include the first ever discrete-logarithm argument for general statements with logarithmic communication cost, the first ever three-move discrete-logarithm argument for arithmetic circuit satisfiability with sub-linear communication costs, and an argument for list membership with sub-logarithmic communication, less than the number of bits required to specify a list index. Every single one of our protocols improves the theoretical state-of-the-art.
Democratic principles demand that every voter should be able to individually verify that their vote is recorded as intended and counted as recorded, without having to trust any authorities. However, most end-to-end (E2E) verifiable voting protocols that provide universal verifiability and voter secrecy implicitly require to trust some authorities or auditors for the correctness guarantees that they provide.
In this paper, we explore the notion of individual verifiability. We evaluate the existing E2E voting protocols and propose a new protocol that guarantees such verifiability without any trust requirements. Our construction depends on a novel vote commitment scheme to capture voter intent that allows voters to obtain a direct zero-knowledge proof of their vote being recorded as intended. We also ensure protection against spurious vote injection or deletion post eligibility verification, and polling-booth level community profiling.
This paper introduces a new capability for group signatures called message-dependent opening . It is intended to weaken the high trust placed on the opener; i.e., no anonymity against the opener is provided by an ordinary group signature scheme. In a group signature scheme with message-dependent opening (GS-MDO), in addition to the opener, we set up an admitter that is not able to extract any user’s identity but admits the opener to open signatures by specifying messages where signatures on the specified messages will be opened by the opener. The opener cannot extract the signer’s identity from any signature whose corresponding message is not specified by the admitter. This paper presents formal definitions of GS-MDO and proposes a generic construction of it from identity-based encryption and adaptive non-interactive zero-knowledge proofs. Moreover, we propose two specific constructions, one in the standard model and one in the random oracle model. Our scheme in the standard model is an instantiation of our generic construction but the message-dependent opening property is bounded. In contrast, our scheme in the random oracle model is not a direct instantiation of our generic construction but is optimized to increase efficiency and achieves the unbounded message-dependent opening property. Furthermore, we also demonstrate that GS-MDO implies identity-based encryption, thus implying that identity-based encryption is essential for designing GS-MDO schemes.
Samad M. E. Sepasgozar, Reyhaneh Karimi, Sara Shirowzhan, Mohammad Mojtahedi · 6 authors
Delay is one of the main challenges of construction projects, and there is still much to overcome in order to reach near zero delay in all construction projects. This project aims to conduct a systematic critical review including a bibliography analysis on delay literature in construction. The main questions consider what has been learnt from a decade investigating delay causes and effects in the construction literature and what factors have been missed in the literature. This paper also presents a new and challenging question regarding how digital tools and associated technologies may prevent any delay in construction projects, which can change the research direction from delay investigations to identifying prevention factors. The paper identifies the delay dataset, including 493 papers investigating delay in construction, and establishes a specific dataset of papers focusing on delay effects and causes (DEC), including 94 selected papers covering different factors examined in over 29 countries such as Iran, India, Turkey, Bangladesh, Saudi Arabia, the United Arab Emirates (UAE), Cambodia, Oman, Malaysia, Taiwan, China, Vietnam, the US, the UK, and Egypt. In addition, the paper identifies 30 critical factors with the frequency of occurrences over three times in the DEC dataset and computes their medians of ranking. This paper also discusses digital tools and methods that can be used for delay analysis and preventions, including MS Project, Oracle Primavera P6, and Open Plan by Deltek. The paper discusses the project schedule delay analysis from project management methodology perspectives. It also discusses the current method’s limitations and future directions, which are based on the identification of the deficiency areas. In total, four overlooked factors are identified and suggested, including faulty data analysis, unmatched structure of the research questionnaires with new knowledge and standards [e.g., Project Management Body of Knowledge (PMBOK)], overlooked effects of digital technologies [e.g., Digital twin, Navisworks, Building Information Model (BIM), Geographic Information System (GIS), and Integrated Project Delivery (IPD)], and ignored job-site technologies. In addition, the paper presents the DEC model for future studies, including four main key factors. These factors are resources (e.g., project budgets, labour, material, equipment, and digital tool), project context, stakeholders performance (e.g., owner/client, consultant/designer, contractor, vendor/supplier), and external factors (e.g., ground condition, site location, regulation, natural disaster), which may significantly affect delay prevention and should be concurrently considered in the future delay investigations, since they may be required for designing an effective mitigation strategy when these proof points are identified. This would significantly help to utilise digital systems to prevent time overruns in different construction contexts.
A primary concern of a wireless sensor network (WSN) is to gather data from the immediate environment of it sensors while minimizing the use of limited network and computational resources. Several studies have focused on how to efficiently store and process sensed data in WSN. Generally, the appropriate method to store sensed data depends on the application for which the WSN was deployed. No matter the application, data collection appears to be a primary function of a WSN. The execution of this function must be coordinated and effective in order to provide WSN with current security standards such as privacy, data integrity and end entity authentication between communicating peers. In this paper, we propose an efficient authentication-based security scheme for data retrieval in WSN. This security scheme combines zero-knowledge proofs (ZKP) and pre-shared key method to provide secured and authenticated communication during data retrieval by a mobile sink in WSN. The security mechanism proposed works on a clustered network topology with an index-based data dissemination scheme. The network employs the concept of Connected Dominating Set (CDS) to form storage and index node sets. Upon a successful peer authentication, the index, located on the index node, is used for efficient retrieval of data. The scheme also provides end-to-end confidentiality given that data is being encrypted before transferred and can be decrypted only at the base station. Security and performance analysis of the proposed scheme show that it addresses all of the aforementioned issues while also satisfying zero-knowledge proofs properties. It is also suitable for devices with limited computational resources as the network can fulfil the purpose of data collection and can be deployed in large-scale wireless sensor networks.
This study investigates the role and functionality of special nucleotide sequences (DNA signatures) to detect the presence of an organism and to distinguish it from all others. After highlighting vulnerabilities of the prevalent DNA signature paradigm for the identification of agricultural genetically modified (GM) organisms it will be argued that these so-called signatures really are no signatures at all - when compared to the notion of traditional (handwritten) signatures and their generalizations in the modern (digital) world. It is suggested that a recent contamination event of an unauthorized GM Bacillus subtilis strain (Paracchini et al. (2017)) in Europe could have been - or the same way could be - the consequence of exploiting gaps of prevailing DNA signatures. Moreover, a recent study (Mueller (2019)) proposes that such DNA signatures may intentionally be exploited to support the counterfeiting or even weaponization of GM organisms (GMOs). These concerns mandate a re-conceptualization of how DNA signatures need to be realized. After identifying central issues of the new vulnerabilities and overlying them with practical challenges that bio-cyber hackers would be facing, recommendations are made how DNA signatures may be enhanced. To overcome the core problem of signature transferability in bioengineered mediums, it is necessary that the identifier needs to remain secret during the entire verification process. On the other hand, however, the goal of DNA signatures is to enable public verifiability, leading to a paradoxical dilemma. It is shown that this can be addressed with ideas that underlie special cryptographic signatures, in particular those of ‘zero-knowledge’ and ‘invisibility.’ This means more than mere signature hiding, but relies on a knowledge-based proof and differentiation of a secret (here, as assigned to specific clones) which can be realized without explicit demonstration of that secret. A reconceptualization of these principles can be used in form of a combined (digital and physical) method to establish confidentiality and prevent un-impersonation of the manufacturer. As a result, this helps mitigate the circulation of possibly hazardous GMO counterfeits and also addresses the situation whereby attackers try to blame producers for deliberately implanting illicit adulterations hidden within authorized GMOs.
Recent advances in the cryptographic field of "Zero-Knowledge Proofs" have sparked a new wave of research, giving birth to many exciting theoretical approaches in the last few years. Such research has often overlapped with the need for private and scalable solutions of Blockchain-based communities, resulting in the first practical implementations of such systems. Many of these innovative constructions have developed in parallel, using different terminologies and evolving into a fragmented ecosystem, calling for their consolidation into the more stable domain of "Verifiable Computation". In this master thesis I propose a unifying Verifiable Computation model for the simplification and efficient comparison of all cryptographic proof systems. I take advantage of this model to analyse innovative technologies (Homomorphic Authenticators, Verifiable Delay Functions) which developed into their own specialised domains, and I attempt to make them more accessible for newcomers to the field. Furthermore, I expand on the future of Verifiable Computation, Universal proof compilers and "Proofs of All", by approaching the state-of-the-art zk-STARK construction from a more accessible and informal design perspective.
Insufficient authentication and authorization of interconnected components are major risks in the Industrial Control System (ICS). To address this, we introduce CyRA, a realtime risk-based security assessment framework that consists of a Nested-ICS security architecture, secure registration protocol, and risk-based multi-factor authentication protocol by which every component is authenticated and authorized to ensure secure communications and prevent cyber attacks in the ICS. Our proposed framework applies Zero-Knowledge Proof of Knowledge (ZKPK) to perform risk-based multi-factor authentication and authorization using a digitally signed identity that encodes secrets provided by the component. Our approach is based on Threat Modeling (TM), Vulnerability Identification (VI), and Consequence Analysis (CA) to provide adequate and efficient authentication and authorization in the ICS. The resilience of our framework is evaluated against recent well-known cyber attacks. Specifically, we conduct a risk-based security assessment for a Safety Instrumentation System (SIS) communication protocol, known as TriStation. The results show that our framework enhances the security of the protocol in dealing with real-time uncertainty of threats, vulnerabilities, and consequences from a new cyber-attack, known as TRITON malware.
Participants can complete tasks on crowdsensing platform with smart mobile devices. They go to specific locations to collect data and upload them. Then, the platform pays them some rewards. However, most of the existing crowdsensing platforms are deployed on centralized servers, which are vulnerable to attack, intrusion, and manipulation. In addition, the location information in task records increases the potential risk of privacy leakage. To reach a balance between privacy protection and functional availability of the system. We design and implement Crowdchain, which is a location preserve anonymous payment system based on a permissioned blockchain. In order to disassociate participants identity information from task records, Crowdchain contains a novel protocol that makes participants transfer wallet address to payment system bypass the crowdsensing platform and receive task rewards correctly. We prove the security of our anonymous payment system by zero-knowledge proof and give the analysis result of system stability.
Malik Hamza Murtaza, Zahoor Ahmed Alizai, Zubair Iqbal
This paper presents a very simple approach for a fair electronic voting system that guarantees anonymity, coercion resistance, correctness, easy tallying, eligibility, fairness, high availability, integrity, robustness, voter authentication, voter confidentiality, vote verifiability and public verifiability of any electoral process. These properties are achieved using blockchain technology. A relatively new type of zero knowledge proof known as zkSNARKs has been used to provide voter unlinkability.
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
Hasan Al-Aswad, Hesham Hasan, Wael Elmedany, Mazen Ali · 5 authors
Blockchain-based applications cover numerous fields from financial services to the Internet of Things (IoT). The smart contracts which are the programmable blocks that execute predefined command are executed on participating nodes. Such execution leads to privacy and confidentiality issues as nodes process data to execute the smart contracts. A zero-knowledge proof is used in cryptocurrencies for allowing spending digital money without revealing the identity of persons. In this paper, we aim to introduce a zero-knowledge proof model using blockchain to enable sharing data securely between services and devices without affecting the confidentiality or privacy of data. The security model fuses digital assets within a blockchain and serves as a trustless layer for protecting the data, which results in enhancing the security of data sharing. We apply the model to two recently introduced concepts in Bahrain: The National Healthcare Insurance Scheme and government-collected VAT. Applying the model for exchanging medical data and sharing medical records between the private sector and public sector will enable maintaining the privacy of patients and increasing efficiency of operations. For VAT, the model helps secure the overall process of VAT reporting and B2B transactional processes in general.
E-cash has its merits comparing with other payment modes. However, there are two problems, which are how to achieve practical/complete tracing and how to achieve it in compact E-cash. First, the bank and the TTP (i.e., trusted third party) have different duties and powers in the reality. Therefore, double-spending tracing is bank's task, while unconditional tracing is TTP's task. In addition, it is desirable to provide lost-coin tracing before they are spent by anyone else. Second, compact E-cash is an efficient scheme, but tracing the coins from double-spender without TTP results in poor efficiency. To solve the problems, we present a compact E-cash scheme. For this purpose, we design an embedded structure of knowledge proof based on a new pseudorandom function and improve the computation complexity from O(k) to O(1). Double-spending tracing needs leaking dishonest users' secret knowledge, but preserving the anonymity of honest users needs zero-knowledge property, and our special knowledge proof achieves it with complete proofs. Moreover, the design is also useful for other applications, where both keeping zero-knowledge and leaking information are necessary.
From hairbrushes to scales, all devices have sensors embedded in them to collect and communicate data. Smart Healthcare is proving to be an exciting and dynamic area with lots of room for new innovations and the increasing consumer demand for proactive health monitoring devices. Having India poised to spend a lot on healthcare, recent innovations using IoT devices and big data analytics can propel the healthcare industry into the future. Smart healthcare providers are leveraging cloud computing with fog computing to optimize their healthcare services. These smart healthcare applications depend mainly on the raw sensor data collected, aggregated, and analyzed by the smart sensors. Smart sensors these days generate myriad amount of data like text, image, audio, and video that require real-time or batch processing. Aggregating these diverse data from various types of resources remains a dispute till date. To resolve this issue, we have proposed a softwarized infrastructure that integrates cloud computing and fog computing, message brokers, and Tor for supple, safe, viable, and a concealed IoT exploitation for smart healthcare applications and services. Our proposed platform employs machine-to-machine (M2M) messaging, data fusion and decision fusion, and uses rule-based beacons for seamless data management. Our proposed flexBeacon system provides an IoT infrastructure that is nimble, secure, flexible, private, and reasonable. We have also proposed an M2M transceiver and microcontroller for flawless data incorporation of smart healthcare applications and services. Based on the IoT devices’ technical capabilities and resource availability, some systems are capable of making use of homomorphic encryption and zero knowledge proofs. The proposed flexBeacon platform offers seamless management and data aggregation without loss of accuracy. The cost of implementing a softwarized IoT for smart healthcare is also greatly reduced.
User authentication can rely on various factors (e.g., a password, a cryptographic key, biometric data) but should not reveal any secret or private information. This seemingly paradoxical feat can be achieved through zero-knowledge proofs. Unfortunately, naive password-based approaches still prevail on the web. Multi-factor authentication schemes address some of the weaknesses of the traditional login process, but generally have deployability issues or degrade usability even further as they assume users do not possess adequate hardware. This assumption no longer holds: smartphones with biometric sensors, cameras, short-range communication capabilities, and unlimited data plans have become ubiquitous. In this paper, we show that, assuming the user has such a device, both security and usability can be drastically improved using an augmented password-authenticated key agreement (PAKE) protocol and message authentication codes.
Tamadun Malayonesia yang sarjananya menggunakan bahasa Melayu sebagai pengungkap kecendekiawanannya, masih belum diiktiraf kewujudannya oleh sarjana Barat kerana ketiadaan bukti bertulis pencapaiannya yang tinggi dalam KeJuTSAMA/STEM. Dalam usaha memperbaiki keadaan inilah maka kami telah melakukan penyelidikan, ekskavasi ilmu, sejak 1990-an bagi memperoleh unsur-unsur sains dan matematik (SAMA) dalam bahasa Melayu yang asli dan terkehadapan daripada bangsa lain sezamannya terutamanya Inggeris. Di sini dipaparkan beberapa hasil penyelidikan yang mutakhir tentang perkara tersebut, khususnya untuk bidang angka. Ditunjukkan bahawa bangsa Malayonesia berbahasa Melayu adalah pencipta terawal di dunia sistem angka perpuluhan seperti sekarang ini, sekaligus menjadikan bangsa pencipta angka kosong yang tertua di dunia. Hal ini bertentangan dengan kepercayaan dunia selama ini bahawa sistem angka perpuluhan dengan kosong adalah ciptaan tamadun Hindu, Islam atau Khmer Lama. The existence of the Malayonesian civilization in which her scholars used Malay as the their intellectual expresions, has not yet been recognised by Western sholars because of lack of written proof in her achievement in STEM. In an effort to improve the situation, we have done some knowledge excavation since 1990s in order to obtain original elements of science in Malay language which were ahead of their counterpart in different countries in Europe especially UK at the same period of time. The latest results are presented here, particularly in the fields of numerals. It is shown that the Malayonesian numeral decimal system with her own zero symbol is the oldest in the world. This contradicts the present belief that the decimal numeral system was invented by the Hindu, the Islamic or the Old Khmer civilisation.
Eduardo Morais, Tommy Koens, Cees van Wijk, Aleksei Koren
In last years, there has been an increasing effort to leverage Distributed Ledger Technology (DLT), including blockchain. One of the main topics of interest, given its importance, is the research and development of privacy mechanisms, as for example is the case of Zero Knowledge Proofs (ZKP). ZKP is a cryptographic technique that can be used to hide information that is put into the ledger, while still allowing to perform validation of this data. In this work we describe different strategies to construct Zero Knowledge Range Proofs (ZKRP), as for example the scheme proposed by Boudot in 2001; the one proposed in 2008 by Camenisch et al, and Bulletproofs, proposed in 2017. We also compare these strategies and discuss possible use cases. Since Bulletproofs is the most efficient construction, we will give a detailed description of its algorithms and optimizations. Bulletproofs is not only more efficient than previous schemes, but also avoids the trusted setup, which is a requirement that is not desirable in the context of Distributed Ledger Technology (DLT) and blockchain. In case of cryptocurrencies, if the setup phase is compromised, it would be possible to generate money out of thin air. Interestingly, Bulletproofs can also be used to construct generic Zero Knowledge Proofs (ZKP), in the sense that it can be used to prove generic statements, and thus it is not only restricted to ZKRP, but it can be used for any kind of Proof of Knowledge (PoK). Hence Bulletproofs leads to a more powerful tool to provide privacy for DLT. Here we describe in detail the algorithms involved in Bulletproofs protocol for ZKRP. Also, we present our implementation, which was open sourced.
We consider two-dimensional zero-temperature systems of $N$ particles to which we associate an energy of the form $$ \mathcal{E}[V](X):=\sum_{1\le i<j\le N}V(|X(i)-X(j)|), $$ where $X(j)\in\mathbb R^2$ represents the position of the particle $j$ and $V(r)\in\mathbb R$ is the {pairwise interaction} energy potential of two particles placed at distance $r$. We show that under suitable assumptions on the single-well potential $V$, the ground state energy per particle converges to an explicit constant $\bar{\mathcal E}_{\mathrm{sq}}[V]$ which is the same as the energy per particle in the square lattice infinite configuration. We thus have $$ N{\bar{\mathcal E}_{\mathrm{sq}}[V]}\le \min_{X:\{1,\ldots,N\}\to\mathbb R^2}\mathcal E[V](X)\le N{\bar{\mathcal E}_{\mathrm{sq}}[V]}+O(N^{\frac 1 2}). $$ Moreover $\bar{\mathcal E}_{\mathrm{sq}}[V]$ is also re-expressed as the minimizer of a four point energy. In particular, this happen{s} if the potential $V$ is such that $V(r)=+\infty$ for $r<1$, $V(r)=-1$ for $r\in [1,\sqrt{2}]$, $V(r)=0$ if $r>\sqrt{2}$, in which case ${\bar{\mathcal E}_{\mathrm{sq}}[V]}=-4$. To the best of our knowledge, this is the first proof of crystallization to the square lattice for a two-body interaction energy.
In this paper, we propose a system for mixing transactions in payment networks such as credit networks. Credit networks like Ripple and Stellar are increasingly popular, and can facilitate crosscurrency transactions in a fraction of the time it would take for banks or other financial institutions to process the same transaction, and at a fraction of the cost. Unlike for cryptocurrencies, there has been little work in the area of designing secure and private mixers for credit networks. Mixers for cryptocurrencies such as Bitcoin cannot be directly applied to the credit network domain because credit networks have an inherently different structure and purpose than cryptocurrencies. We design a system that uses cryptographic constructs such as ring signatures, commitments, and zero knowledge proofs to provide security/integrity of all transactions, ensures privacy of the users involved in a transaction, as well as privacy of the amount transacted. We also provide preliminary experimental results.