Blockchain Papers

Albert Guan, Wen-Guey Tzeng

No abstract is available for this record.

Anik Islam, Mohammed Belal Uddin, Md. Fazlul Kader, Soo Young Shin

Non-orthogonal multiple access (NOMA) with successive interference cancellation receiver is considered as one of the most potent multiple access techniques to be adopted in future wireless communication networks. Data security in the NOMA transmission scheme is on much attention drawing issue. Blockchain is a distributed peer-to-peer network enables a way of protecting information from unauthorized access, tempering etc. By utilizing encryption techniques of blockchain, a secured data communication scheme using blockchain in NOMA is proposed in this paper. A two-phase encryption technique with key generation using different parameter is proposed. In the first-phase data is encrypted by imposing users' public key and in the second phase, a private key of the base station (BS) is engaged for encryption. Finally, the superiority of the proposed scheme over existing scheme is proven through a comparative study based on the different features.

Colin Mallett

No abstract is available for this record.

Di Lin, Yu Tang

A device-to-device (D2D) underlying cellular network is pervasive to support various wireless applications. However, due to the dramatic increase of data transmission in the network with limited amount of wireless resource, a few users may be required to temporarily disconnect from the network to avoid the interruption of data transmission in the whole network. A critical issue of determining the user access in D2D underlying networks is the authenticity of channel state information (CSI), and usually, a user with a higher CSI can be allocated a larger amount of wireless resource or have a higher probability of staying in the network. In this paper, we propose a blockchain consensus-based scheme to verify the authenticity of CSI and add the users who intentionally advocate a higher value of CSI into a fraud chain. Also, we consider both the cross-tier interference caused by a mobile user and the presence of a user in the fraud chain to determine the access of a user. The analysis results show that our proposed user access scheme can enhance the network performance by efficiently controlling the use access in mobile applications.

J. S. Hammudoglu, J. Sparreboom, J. I. Rauhamaa, J. K. Faber · 8 authors

We devised a mobile biometric-based authentication system only relying on local processing. Our Android open source solution explores the capability of current smartphones to acquire, process and match fingerprints using only its built-in hardware. Our architecture is specifically designed to run completely locally and autonomously, not requiring any cloud service, server, or permissioned access to fingerprint reader hardware. It involves three main stages, starting with the fingerprint acquisition using the smartphone camera, followed by a processing pipeline to obtain minutiae features and a final step for matching against other locally stored fingerprints, based on Oriented FAST and Rotated BRIEF (ORB) descriptors. We obtained a mean matching accuracy of 55%, with the highest value of 67% for thumb fingers. Our ability to capture and process a finger fingerprint in mere seconds using a smartphone makes this work usable in a wide range of scenarios, for instance, offline remote regions. This work is specifically designed to be a key building block for a self-sovereign identity solution and integrate with our permissionless blockchain for identity and key attestation.

Florian Kerschbaum, Martín Beck, Dagmar Schönfeld

Privacy is of the utmost importance in genomic matching. Therefore a number of privacy-preserving protocols have been presented using secure computation. Nevertheless, none of these protocols prevents inferences from the result. Goodrich has shown that this resulting information is sufficient for an effective attack on genome databases. In this paper we present an approach that can detect and mitigate such an attack on encrypted messages while still preserving the privacy of both parties. Note that randomization, e.g.~using differential privacy, will almost certainly destroy the utility of the matching result. We combine two known cryptographic primitives -- secure computation of the edit distance and fuzzy commitments -- in order to prevent submission of similar genome sequences. Particularly, we contribute an efficient zero-knowledge proof that the same input has been used in both primitives. We show that using our approach it is feasible to preserve privacy in genome matching and also detect and mitigate Goodrich's attack.

Zhengrui Qin, Shanhe Yi, Qun Li, Dmitry Zamkov

Cognitive radio plays an important role in improving spectrum utilization in wireless services. In the cognitive radio paradigm, secondary users (SUs) are allowed to utilize licensed spectrum opportunistically without interfering with primary users (PUs). To motivate PU to share licensed spectrum with SU, it is reasonable for SU to pay PU a fee whenever the former is utilizing the latter's licensed spectrum. SU's detailed usage information, such as when and how long the licensed spectrum is utilized, is needed for PU to calculate payment. Providing usage information to PU, however, may compromise SU's privacy. To solve this dilemma, we are the first to propose a novel privacy-preserving mechanism for cognitive radio transactions through commitment scheme and zero-knowledge proof. This mechanism, on one hand, only allows PU to know the total payment to SU for a billing period, plus a little portion of SU's usage information. On the other hand, it guarantees PU that the payment is correctly calculated. We have implemented our mechanism and evaluated its performance.

Maria Letizia Perugini

Los motivos históricos y económicos que han llevado a programar el protocolo Bitcoin se encuentran en la actualidad con una interesante fase evolutiva de los algoritmos de encriptación para la identificación de datos y la transmisión de derechos, tratándose de un sistema que presenta aspectos jurídicos dignos de mención.

Michael Backes, Aniket Kate, Sebastian Meiser, Tim Ruffing

Cryptographic protocols are commonly designed and their security proven under the assumption that the protocol parties have access to perfect (uniform) randomness. Physical randomness sources deployed in practical implementations of these protocols often fall short in meeting this assumption, but instead provide only a steady stream of bits with certain high entropy. Trying to ground cryptographic protocols on such imperfect, weaker sources of randomness has thus far mostly given rise to a multitude of impossibility results, including the impossibility to construct provably secure encryption, commitments, secret sharing, and zero-knowledge proofs based solely on a weak source. More generally, indistinguishability-based properties break down for such weak sources. In this paper, we show that the loss of security induced by using a weak source can be meaningfully quantified if the source is bounded, e.g., for the well-studied Santha-Vazirani (SV) sources. The quantification relies on a novel relaxation of indistinguishability by a quantitative parameter. We call the resulting notion dierential indistinguishability in order to reflect its structural similarity to dierential privacy. More concretely, we prove that indistinguishability with uniform randomness implies dierential indistinguishability with weak randomness. We show that if the amount of weak randomness is limited (e.g., by using it only to seed a PRG), all cryptographic primitives and protocols still achieve dierential indistinguishability.

Chunming Tang, Shuhong Gao

In a traditional (t, n)-threshold secret sharing scheme, t or more honest participants can reconstruct the secret K. In the reconstruction process, the individual shares and the secret key K are revealed, hence K is shared once only. In this paper, we firstly give the definition of leakproof secret sharing scheme which is composed of a distribution protocol and a proof protocol, then propose two leakproof secret sharing protocols, a computationally secure protocol and an information-theoretically secure protocol. In our protocols, t or more participants can jointly prove that they hold the secret K by using a multi-prover zero-knowledge argument of knowledge. As a result, the secret K will be shared for as many times as desired. Furthermore, each participant can detect the dealer in the distribution protocol from cheating, and any verifier can prevent non-qualified set of participants in proof protocol from cheating. As an example of the practical impact of our work we use our techniques to construct group identification schemes with zero-knowledge.

Lifeng Sang

A sensor network typically refers to a collection of sensor nodes equipped with sensing, communication and processing capabilities. It brings an opportunity to solve many difficult problems including real time monitoring, tracking, and controlling. While the applications of sensor networking become many and varied, security has always been one of the major concerns in real deployments. In this dissertation, we design physical primitives for secure communication in wireless sensor networks, and develop a wireless security framework to provide conventional security services. We investigate the feasibility of achieving perfect secrecy and information authenticity without shared secrets via two physical primitives: (i) cooperative jamming primitive, where we introduce a secure coding problem in which not only the sender but also the receiver participates in the coding. In essence, the receiver’s role is to selectively jam the sender’s transmission at the level of bits, bytes, or packets. We then design a class of secure codes, called “dialog codes”, for diverse channel models and receiver models. (ii) spatial verification primitive, where we exploit the spatial signature induced by the radio communications of a node on its neighboring nodes, and design a spatial primitive that robustly and efficiently validates the authenticity of the source of messages. To address trust initialization, we propose a zero knowledge proof alternative that allows bootstrapping trust among individuals in a distributed way.

Puwen Wei, Guoyan Zhang, Lijiang Zhang, Xiaoyun Wang

This paper shows that the protocol presented by Goyal et al. can be further simplified for a one-way function, with the simplified protocol being more practical for the decisional Diffie-Hellman assumption. Goyal et al. provided a general transformation from any honest verifier statistical zero-knowledge argument to a concurrent statistical zero-knowledge argument. Their transformation relies only on the existence of one-way functions. For the simplified transformation, the witness indistinguishable proof of knowledge protocols in “parallel” not only plays the role of preamble but also removes some computational zero-knowledge proofs, which Goyal et al. used to prove the existence of the valid openings to the commitments. Therefore, although some computational zero-knowledge proofs are replaced with a weaker notion, the witness indistinguishable protocol, the proof of soundness can still go through.

Caimu Tang, Dapeng Wu

In this paper, a non-interactive zero-knowledge proof scheme is proposed for secure identification in wireless networks, and it uses a timed oblivious transfer technique to enable a single verifier to identify multiple provers. The verifier and the prover do not need to be synchronized in this scheme. This scheme also enjoys the distance-bounding property which makes the proposed scheme invulnerable to the relay attack. We propose to use the order statistic for the detection of relay attackers. We show that it is optimal in terms of minimum variance. Finally, we shed some light on implementation issues of our proposed scheme.

Syed A. Jafar, M.J. Fakhereddin

In this correspondence, we show that the exact number of spatial degrees of freedom (DOF) for a two user nondegenerate (full rank channel matrices) multiple-input-multiple-output (MIMO) Gaussian interference channel with M1, M2 antennas at transmitters 1, 2 and N1, N2 antennas at the corresponding receivers, and perfect channel knowledge at all transmitters and receivers, is min{M1 + M2, N1 + M2, max(M1, N2), max(M2, N1)}. A constructive achievability proof shows that zero forcing is sufficient to achieve all the available DOF on the two user MIMO interference channel. We also show through an example of a share-and-transmit scheme how the gains of transmitter cooperation may be entirely offset by the cost of enabling that cooperation so that the available DOF are not increased.

Caimu Tang, Dapeng Wu

In this paper, a non-interactive zero-knowledge proof scheme is proposed for secure identification in wireless networks, and it uses a timed oblivious transfer technique to enable a single verifier to identify multiple provers. The verifier and the prover do not need to be synchronized in this scheme. This scheme also enjoys the distance bounding property which makes the proposed scheme invulnerable to the relay attack. We propose to use the order statistic for the detection of relay attackers. We show that it is optimal in terms of minimum variance. Finally, we will shed some light on implementation issues of our proposed scheme.

H. Imai, Kirill Morozov, Anderson C. A. Nascimento, Andreas Winter

Bit commitment is an important tool for constructing zero-knowledge proofs and multi-party computation. Unconditionally secure bit commitment can be based, in particular, on noisy channel or correlation where noise considered a valuable resource. Recently, Winter, Nascimento and Imai introduced the concept of commitment capacity, the maximal ratio between the length of a string which the sender commits to and the number of times the noisy channel/correlation is used. They also proved that for any discrete memoryless channel there exists a secure protocol achieving its commitment capacity however, no particular construction was given. Solving their open question, we provide an efficient protocol for achieving the commitment capacity of discrete memoryless systems (noisy channels and correlations).

Alejandro Hevia

No abstract is available for this record.

Pino Caballero‐Gil

The aim of this work is to investigate the possibility of designing zero-knowledge identification schemes based on hard-on-average problems. It includes a new two-party identification protocol whose security relies on a discrete mathematics problem classified as DistNP-Complete under the average-case analysis, the so-called Distributional Matrix Representability Problem. Thanks to the use of the search version of the mentioned problem, the zero-knowledge property is formally proved by black-box simulation, and consequently the security of the proposed scheme is actually guaranteed. Furthermore, with the proposal of a new zero-knowledge proof based on a problem never used before for this purpose, the set of tools for designing cryptographic applications is enlarged.

Ivan Damgård, Torben Pryds Pedersen, Birgit Pfitzmann

<p>We present and compare definitions of the notion of "statistically<br />hiding" protocols, and we propose a novel statistically hiding commitment<br />scheme. Informally, a protocol statistically hides a secret if a<br />computationally unlimited adversary who conducts the protocol with<br />the owner of the secret learns almost nothing about it. One definition<br />is based on the L1-norm distance between probability distributions,<br />the other on information theory. We prove that the two definitions are<br />essentially equivalent. For completeness, we also show that statistical<br />counterparts of definitions of computational secrecy are essentially<br />equivalent to our main definitions. Commitment schemes are an important<br /> cryptologic primitive. Their purpose is to commit one party to a certain value,<br /> while hiding this value from the other party until some later time.<br /> We present a statistically<br />hiding commitment scheme allowing commitment to many<br />bits. The commitment and reveal protocols of this scheme are constant<br />round, and the size of a commitment is independent of the number of<br />bits committed to. This also holds for the total communication complexity,<br />except of course for the bits needed to send the secret when it<br />is revealed. The proof of the hiding property exploits the equivalence<br />of the two definitions.</p><p>Index terms -- Cryptology, Shannon theory, unconditional security,<br />statistically hiding, multi-bit commitment, similarity of ensembles<br />of distributions, zero-knowledge, protocols.</p><p> </p>