Can an exchange be “dark,” so that orders are not displayed, while simultaneously trustworthy, so that the execution of trades and flow of information occur as promised? SEC actions against dark pools suggest cause for concern, and regulators seem to be moving towards requiring more disclosure. Yet there is a clear tension: trading order information is widely exploited. Therefore, institutional investors have a strong interest in keeping pre-trade information about large trades hidden. Secrecy-preserving proofs of correctness can be used to build trust without revealing unnecessary information. By performing operations on obfuscated representations of orders (perhaps encrypted or otherwise hidden), a zero knowledge proof can be provided, allowing anyone to verify correctness of trades. Crucially, this can be done without revealing any information beyond this correctness. This technology can be usefully applied to construct provably trustworthy dark pools. Additional practical protocols relax the definition of “zero knowledge" to reveal limited information, providing necessary transparency for efficient market operation while limiting information that can be exploited by observers. Coupled with Trusted Computing hardware, these protocols can provide an excellent balance of practicality with secrecy
The Bitcoin cryptocurrency relies heavily on a variety of cryptographic functions and operations, which are currently assumed to be secure, but will inevitably be broken in the future. As Bitcoin tries to compete against traditional currencies, it remains to be seen how the Bitcoin protocol will need to change in response to weakened cryptography. To this end, this study systematically evaluates the effects of broken cryptographic primitives on the operation of the Bitcoin network, and the changes to the Bitcoin protocol that will be necessary in response. We conclude that a broken hash function only requires switching over to a new hash function, without the need to re-write the blockchain, and is well serviced by the “checkpoint” mechanisms already built into Bitcoin. However, a vulnerability of the signature scheme cannot be dealt with in the same manner without side-e.ects, as it may lead to lost or stolen coins, even if the process is gradual and is conducted before the cryptographic primitive is broken. We conclude that solving this problem either requires some degree of centralization, or the use of Zero-Knowledge Proofs along or on top of Bitcoin.
Michele Ciampi, Giuseppe Persiano, Luisa Siniscalchi, Ivan Visconti
The Fiat-Shamir (FS) transform is a popular technique for obtaining practical zero-knowledge argument systems. The FS transform uses a hash function to generate, without any further over-head, non-interactive zero-knowledge (NIZK) argument systems from public-coin honest-verifier zero-knowledge (public-coin HVZK) proof systems. In the proof of zero knowledge, the hash function is modeled as a programmable random oracle (PRO). In TCC 2015, Lindell embarked on the challenging task of obtaining a similar transform with improved heuristic security. Lindell showed that, for several interesting and practical languages, there exists an efficient transform in the non-programmable random oracle (NPRO) model that also uses a common reference string (CRS). A major contribution of Lindell’s transform is that zero knowledge is proved without random oracles and this is an important step towards achieving efficient NIZK arguments in the CRS model without random oracles. In this work, we analyze the efficiency and generality of Lindell’s transform and notice a significant gap when compared with the FS transform. We then propose a new transform that aims at filling this gap. Indeed our transform is almost as efficient as the FS transform and can be applied to a broad class of public-coin HVZK proof systems. Our transform requires a CRS and an NPRO in the proof of soundness, similarly to Lindell’s transform. 1
Abstract. LowMC is a collection of block cipher families introduced at Eurocrypt 2015 by Albrecht et al. Its design is optimized for instanti-ations of multi-party computation, fully homomorphic encryption, and zero-knowledge proofs. A unique feature of LowMC is that its internal affine layers are chosen at random, and thus each block cipher family contains a huge number of instances. The Eurocrypt paper proposed two specific block cipher families of LowMC, having 80-bit and 128-bit keys. In this paper, we mount interpolation attacks (algebraic attacks intro-duced by Jakobsen and Knudsen) on LowMC, and show that a practically significant fraction of 2−38 of its 80-bit key instances could be broken 223 times faster than exhaustive search. Moreover, essentially all instances that are claimed to provide 128-bit security could be broken about 1000 times faster. In order to obtain these results, we had to develop novel techniques and optimize the original interpolation attack in new ways. While some of our new techniques exploit specific internal properties of LowMC, others are more generic and could be applied, in principle, to any block cipher.
Matteo Maffei, Giulio Malavolta, Manuel Reinert, Dominique Schröder
Cloud storage has rapidly become a cornerstone of many IT infrastructures, constituting a seamless solution for the backup, synchronization, and sharing of large amounts of data. Putting user data in the direct control of cloud service providers, however, raises security and privacy concerns related to the integrity of outsourced data, the accidental or intentional leakage of sensitive information, the profiling of user activities and so on. Furthermore, even if the cloud provider is trusted, users having access to outsourced files might be malicious and misbehave. These concerns are particularly serious in sensitive applications like personal health records and credit score systems. To tackle this problem, we present GORAM, a cryptographic system that protects the secrecy and integrity of outsourced data with respect to both an untrusted server and malicious clients, guarantees the anonymity and unlink ability of accesses to such data, and allows the data owner to share outsourced data with other clients, selectively granting them read and write permissions. GORAM is the first system to achieve such a wide range of security and privacy properties for outsourced storage. In the process of designing an efficient construction, we developed two new, generally applicable cryptographic schemes, namely, batched zero-knowledge proofs of shuffle and an accountability technique based on chameleon signatures, which we consider of independent interest. We implemented GORAM in Amazon Elastic Compute Cloud (EC2) and ran a performance evaluation demonstrating the scalability and efficiency of our construction.
Foteini Baldimtsi, Aggelos Kiayias, Thomas Zacharias, Bingsheng Zhang
We introduce a new class of protocols called Proofs of Work or Knowledge (PoWorKs). In a PoWorK, a prover can convince a verifier that she has either performed work or that she possesses knowledge of a witness to a public statement without the verifier being able to distinguish which of the two has taken place. We formalize PoWorK in terms of three basic properties, completeness, f-soundness and indistinguishabil-ity (where f is a function that determines the tightness of the proof of work aspect) and present a construction that transforms 3-move HVZK protocols into 3-move public-coin PoWorKs. To formalize the work aspect in a PoWorK protocol we define cryptographic puzzles that adhere to certain uniformity conditions, which may also be of independent interest. We instantiate our puzzles in the random oracle (RO) model as well as via constructing “dense ” versions of suitably hard one-way functions. We then showcase PoWorK protocols by presenting two applications. We first show how non-interactive PoWorKs can be used to reduce spam email by forcing users sending an e-mail to either prove to the mail server they are approved contacts of the recipient or to perform computational work. As opposed to previous approaches [DN92, DGN03] that applied proofs of work to this problem, our proposal of using PoWorKs is privacy-preserving as it hides the list of the receiver’s approved contacts from the mail server. Our second application for PoWorK relates to zero-knowledge protocols. We show that PoWorK protocols imply straight-line quasi-polynomial simulatable arguments of knowledge; by applying this result to our construction we obtain an efficient straight-line concurrent 3-move statistically quasi-polynomial simulatable argument of knowledge, improving the round complexity of the previously known four-move protocols, [Pas03].
Recent technological advances have given rise to the popularity and success of cloud. This new paradigm is gaining an expanding interest, since it provides cost efficient architectures that support the transmission, storage, and intensive computing of data. However, these promising storage services bring many challenging design issues, considerably due to the loss of data control. These challenges, namely data confidentiality and data integrity, have significant influence on the security and performances of the cloud system. This thesis aims at overcoming this trade-off, while considering two data security concerns. On one hand, we focus on data confidentiality preservation which becomes more complex with flexible data sharing among a dynamic group of users. It requires the secrecy of outsourced data and an efficient sharing of decrypting keys between different authorized users. For this purpose, we, first, proposed a new method relying on the use of ID-Based Cryptography (IBC), where each client acts as a Private Key Generator (PKG). That is, he generates his own public elements and derives his corresponding private key using a secret. Thanks to IBC properties, this contribution is shown to support data privacy and confidentiality, and to be resistant to unauthorized access to data during the sharing process, while considering two realistic threat models, namely an honest but curious server and a malicious user adversary. Second, we define CloudaSec, a public key based solution, which proposes the separation of subscription-based key management and confidentiality-oriented asymmetric encryption policies. That is, CloudaSec enables flexible and scalable deployment of the solution as well as strong security guarantees for outsourced data in cloud servers. Experimental results, under OpenStack Swift, have proven the efficiency of CloudaSec in scalable data sharing, while considering the impact of the cryptographic operations at the client side. On the other hand, we address the Proof of Data Possession (PDP) concern. In fact, the cloud customer should have an efficient way to perform periodical remote integrity verifications, without keeping the data locally, following three substantial aspects : security level, public verifiability, and performance. This concern is magnified by the client’s constrained storage and computation capabilities and the large size of outsourced data. In order to fulfill this security requirement, we first define a new zero-knowledge PDP proto- col that provides deterministic integrity verification guarantees, relying on the uniqueness of the Euclidean Division. These guarantees are considered as interesting, compared to several proposed schemes, presenting probabilistic approaches. Then, we propose SHoPS, a Set-Homomorphic Proof of Data Possession scheme, supporting the 3 levels of data verification. SHoPS enables the cloud client not only to obtain a proof of possession from the remote server, but also to verify that a given data file is distributed across multiple storage devices to achieve a certain desired level of fault tolerance. Indeed, we present the set homomorphism property, which extends malleability to set operations properties, such as union, intersection and inclusion. SHoPS presents high security level and low processing complexity. For instance, SHoPS saves energy within the cloud provider by distributing the computation over multiple nodes. Each node provides proofs of local data block sets. This is to make applicable, a resulting proof over sets of data blocks, satisfying several needs, such as, proofs aggregation
A Mobile Ad-hoc Network (MANET) is a group of wireless mobile nodes that dynamically form a network without any pre-established infrastructure or centralized administration, Soewito (2014). Some network hops may be needed to send a packet from one node to another node in the MANET. To do the communication between the nodes, a route has to be selected in the network, therefore it need a routing protocol that manage selection of the route. Selection route in mobile ad-hoc network is not easy because nodes always move so that the topology of network always changed every time. This is a big issue in selection route in mobile ad-hoc network because the route can be broken anytime. Moreover, MANET is more vulnerable than other wireless communication types because every mobile node serves as both the host and the router and forwards packets on behalf of each other. This study presents the analyzing and evaluation several routing algorithms and a novel scheme to build an authentication system by adding the modified zero knowledge proof algorithm to each mobile node in MANET.
Our focus in the last chapter was on the construction of an analytic function from a knowledge of its singularities.More often than not, however, we are confronted with the inverse problem: given some knowledge of a function in a restricted region of its domain of holomorphy, determine its singularities.This will be the focus of the present chapter.We have seen repeatedly that one need not know all that much about an analytic function in order to determine its value everywhere in the complex plane or on its Riemann surface.Cauchy's Integral Representation can be viewed as the embodiment of this property and thus far it has provided the key to exploiting it.We are now going to nd out what constitutes a minimal set of information for the determination of an analytic function.The answer is one that is best exploited not by Cauchy's Integral but by one of its consequences, the Taylor series.In so doing, we shall also nd out how to use a representation of a function that is valid in one domain of the complex plane to determine its values at points outside the domain or indeed, at any points where it is holomorphic.Our starting point is the following theorem which, despite its innocuous appearance, is one of the most remarkable results of complex analysis.Theorem: Let f (z) and f (z) be holomorphic in a domain D of the complex plane.If the two functions coincide in any neighbourhood, however small, of a point z in D, or even on a point set with an accumulation point in D, then they coincide throughout D. Proof: The function f (z)f (z) is holomorphic throughout D and has a set of zeros consisting of the points where f (z) and f (z) coincide, with an accumulation point in D. We know that in any domain where it is holomorphic a function either has isolated zeros or it is identically zero.Thus,What this theorem establishes is that a holomorphic function is uniquely determined everywhere within its domain of holomorphy by its behaviour in the neighbourhood of an arbitrary point of that domain.But how can one exploit this remarkable property?Obviously not by means of a Cauchy Integral or dispersion representation or anything else of that ilk as we lack the necessary input information.However, what we do have is precisely the information needed to determine a Taylor series representation.Suppose that we know the value of the function f (z) throughout a neighbourhood of the point z = z which is a point lying within the function's domain of holomorphy, D. This is su cient to permit calculation of the coe cients c = f (z ), c = f (z ), . . ., cm = m! f (m) (z ), . . .
Digital signature schemes are a foundational cryptographic building block in certification and the projection of trust. Based on a signature scheme on committed graphs, we propose a framework of certification and proof methods to sign topology graphs and to prove properties of their certificates in zero-knowledge. This framework allows an issuer, such as an auditing system, to sign the topology representation of an infrastructure. The prover, such as an infrastructure provider, can then convince a verifier of topology properties including connectivity and isolation without disclosing the blueprint of the topology itself. By that, we can certify the structure of critical systems while still maintaining confidentiality. We offer zero-knowledge proofs of knowledge for a general specification language of security goals for virtualized infrastructures such that high-level security goals can be proven over topology certificates. We offer an efficient and practical construction, built upon the Camenisch-Lysyanskaya signature scheme, honest-verifier proofs and the strong RSA assumption.
The increasing demand in promoting cloud computing in either business or other areas requires more security of a cloud storage system. Traditional cloud storage systems fail to protect data integrity information (DII), when the interactive messages between the client and the data storage server are sniffed. To protect DII and support public verifiability, we propose a data integrity verification scheme by deploying a designated confirmer signature DCS as a building block. The DCS scheme strikes the balance between public verifiable signatures and zero-knowledge proofs which can address disputes between the cloud storage server and any user, whoever acting as a malicious player during the two-round verification. In addition, our verification scheme remains blockless and stateless, which is important in conducting a secure and efficient cryptosystem. We perform security analysis and performance evaluation on our scheme, and compared with the existing schemes, the results show that our scheme is more secure and efficient.
Shao et al. proposed a novel method for computing private set intersection based on searchable encryption. Compared with the traditional protocols, their technique requires much less computation for the client to obtain the intersection. Concretely, the client only computes m (the cardinality of the client’s input set) multiplications, m hashes, and one modular exponentiation. However, their protocol only satisfies security against semi-honest behaviors. In this paper, we aim to promote the security of Shao et al.’s protocol. Our solution woks in the CRS model, and is based on the non-interactive zero knowledge proof and the succinct non-interactive argument. The proposed protocol satisfies security against malicious adversaries and needs only one round interaction.
The problem of secure multi-party computation(SMPC) is one of the most fundamental problems in information security. First, we introduce the basic concept of SMPC and four SMPC basic agreement: key distribution,oblivious transfer, bit commitment and zero knowledge proof. Secondly, we separately illustrate commitment schemes commitment transfer protocol, commitment sharing protocol and commitment multiplication protocol. Finally, we present unconditionally secure multi-party computation with a passive adversary, an active adversary, general adversary structures.
Provable data possession (PDP) is one of the techniques to ensure the integrity of data in storage outsourcing. Here in this paper, we speak to the creation of an efficient PDP method for distributed cloud storage to maintain the scalability of service and data migration. On the basis on homomorphic verifiable response and hash index hierarchy we projected a cooperative PDP (CPDP) method. We confirm the security of our method based on multi-prover zeroknowledge proof scheme, which can satisfy knowledge soundness, fullness , and zero-knowledge properties. As well, we expressive performance optimization mechanisms for our method, and in particular present an capable method for selecting finest parameter values to reduce the addition expenses of storage service providers and client. Our experiment shows that our solution introduces lower addition and communication overheads in evaluation with noncooperative approaches.
In this paper, we propose a secure yoking proof protocol for RFID passive tags based on Zero Knowledge. The protocols that have been proposed earlier are either found to be vulnerable to certain attacks or do not comply with EPC standard for passive tags because they use complex encryption schemes. Also, the unique design requirements of yoking/grouping proofs have not been fully addressed by many. Our protocol addresses these important security and design gaps in yoking proofs. The proposed protocol uses pseudo random squares and quadratic residuosity to realize the zero knowledge property. Tag operations are limited to functions such as modulo (MOD), exclusive-or (XOR) and 128-bit Pseudo Random Number Generators (PRNG). Passive tags are capable of these operations and hence the protocol achieves EPC compliance and also meets the necessary security requirements.
Mitra Mojtahedi, Aymeric Fouquier d’Hérouël, Sui Huang
Digital PCR (dPCR) exploits limiting dilution of a template into an array of PCR reactions. From this array the number of reactions that contain at least one (as opposed to zero) initial template is determined, allowing inferring the original template concentration. Here we present a novel protocol to efficiently infer the concentration of a sample and its optimal dilution for dPCR from few targeted qPCR assays. By taking advantage of the real-time amplification feature of qPCR as opposed to relying on endpoint PCR assessment as in standard dPCR prior knowledge of template concentration is not necessary. This eliminates the need for serial dilutions in a separate titration and reduces the number of necessary reactions. We describe the theory underlying our approach and discuss experimental moments that contribute to uncertainty. We present data from a controlled experiment where the initial template concentration is known as proof of principle and apply our method on directly monitoring transcript level change during cell differentiation as well as gauging amplicon numbers in cDNA samples after pre-amplification.
Open access
Innovative Microfluidic and Catalytic Techniques Innovation
The Failure Mode and Effect Analysis (FMEA) is a one of the requirements which was required by the Automotive Industries Action Group (AIAG) to all the automotive suppliers and manufacturers worldwide through the TS16949 Quality System. There were a lot of dicrepencies detected on implementing the FMEA which directly related to the user experinces and knowledge. The descrepencies cause the FMEA not meeting the objectives of it. Conceptually, Poka Yoke is able to fit into the Process FMEA. Failure Mode and Effect Analysis (FMEA) helps predict and prevent problems through proper control or detection methods. Mistake proofing emphasizes detection and correction of mistakes before they become defects. Poka Yoke helps people and processes work correctly the first time. It refers to techniques that make mistakes impossible to commit. These techniques eliminate defects from products and processes as well as substantially improve their quality and reliability. Poka Yoke can be considered an extension of FMEA. The use of simple Poka Yoke ideas and methods in product and process design eliminates both human and mechanical errors. Ultimately, both FMEA and Poka Yoke methodologies result in zero defects and benefit either the end or the next-in-line customer. The first concept of Poka Yoke emphasizes elimination of the cause or occurrence of the error that creates the defects by concentrating on the cause of the error in the process. The defect is prevented by stopping the line or the machine when the root cause of the defect is triggered or detected. The second concept of Poka Yoke focuses on the effectiveness of the detection system. The foolproof detection system eliminates the defect or detects the error that causes defects. The implementation of the Poka Yoke concept in a foolproof detection system eliminates the possibility that error or defects will slip through the process and reach the customer.
In this paper, we describe our analysis of a recently proposed electric vehicle charing protocol. The protocol builds on complicated cryptographic primitives such as commitment, zero-knowledge proofs, BBS+ signature and etc. Moreover, interesting properties such as secrecy, authentication, anonymity, and location privacy are claimed on this protocol. It thus presents a challenge for formal verification, as existing tools for security protocol analysis lack support for all the required features. In our analysis, we employ and combine the strength of two state-of-the-art symbolic verifiers, Tamarin and Prove if, to check all important properties of the protocol.