Rahul Saha, Gulshan Kumar, Tannishtha Devgun, William J. Buchanan · 8 authors
The decentralization and transparency have provided wide acceptance of blockchain technology in various sectors through numerous applications. The claimed security services by blockchain have been proved using various cryptographic techniques, mainly public key infrastructure and digital signatures. However, the use of generic cryptographic primitives using large prime numbers or elliptic curves with logarithms is going to be an issue with quantum computers as those techniques are vulnerable in post-quantum era. Therefore, the paradigm shift from pre-quantum to the post-quantum era has necessitated new cryptographic developments which are robust against quantum attacks and applicable in blockchain for post-quantum decentralization. Therefore, we have presented a solution for post-quantum decentralization in the blockchain. It uses lattices with polynomials for identity-based encryption (IBE) and aggregate signatures for the consensus to ensure efficiency and suitability in post-quantum blockchain applications. We experiment the proposed approach based on delay, throughput, energy consumption and complexity. The comparative results prove that the presented work is efficient.
Many of the recent advanced lattice-based \(\varSigma \)-/public-coin honest verifier (HVZK) interactive protocols based on the techniques developed by Lyubashevsky (Asiacryptâ09, Eurocryptâ12) can be transformed into a non-interactive zero-knowledge (NIZK) proof in the random oracle model (ROM) using the Fiat-Shamir transform. Unfortunately, although they are known to be secure in the classical ROM, existing proof techniques are incapable of proving them secure in the quantum ROM (QROM). Alternatively, while we could instead rely on the Unruh transform (Eurocryptâ15), the resulting QROM secure NIZK will incur a large overhead compared to the underlying interactive protocol.
Linear Legendre pseudorandom functions were introduced in 1988 by Damgrd, and higher degree generalisations were introduced by Russell and Shparlinski in 2004. We present new key recovery methods that improve the state of the art for both cases. For degree r 3 we give an attack that runs in time O( p r -3 ) after O( p 3 ) precomputation for the most relevant high degree case; it is based on the action of the group of Mbius transformations on degree r polynomials. For r < 3 we give an O( p r/2 ) attack with O( p r/4 ) oracle queries. In the linear case we recovered the keys for the 64, 74 and 84-bit prime Ethereum challenges, being the first to solve the 84-bit case.
Prabhanjan Ananth, Kai-Min Chung, Rolando L. La Placa
We study the notion of zero-knowledge secure against quantum polynomial-time verifiers (referred to as quantum zero-knowledge) in the concurrent composition setting. Despite being extensively studied in the classical setting, concurrent composition in the quantum setting has hardly been studied. We initiate a formal study of concurrent quantum zero-knowledge. Our results are as follows: -Bounded Concurrent QZK for NP and QMA: Assuming post-quantum one-way functions, there exists a quantum zero-knowledge proof system for NP in the bounded concurrent setting. In this setting, we fix a priori the number of verifiers that can simultaneously interact with the prover. Under the same assumption, we also show that there exists a quantum zero-knowledge proof system for QMA in the bounded concurrency setting. -Quantum Proofs of Knowledge: Assuming quantum hardness of learning with errors (QLWE), there exists a bounded concurrent zero-knowledge proof system for NP satisfying quantum proof of knowledge property. Our extraction mechanism simultaneously allows for extraction probability to be negligibly close to acceptance probability (extractability) and also ensures that the prover's state after extraction is statistically close to the prover's state after interacting with the verifier (simulatability). The seminal work of [Unruh EUROCRYPT'12], and all its followups, satisfied a weaker version of extractability property and moreover, did not achieve simulatability. Our result yields a proof of quantum knowledge system for QMA with better parameters than prior works.
This paper proposes a protocol for lottery and a protocol for auction on quantum Blockchain. Our protocol of lottery satisfies randomness, unpredictability, unforgeability, verifiability, decentralization and unconditional security. Our protocol of auction satisfies bid privacy, posterior privacy, bids' binding, decentralization and unconditional security. Except quantum Blockchain, the main technique involved in both protocols is quantum bit commitment.
SodsMPC is a quantum-safe smart contract system. SodsMPC permissioned servers (verification nodes) execute contracts by secure multi-party computation (MPC) protocols. MPC ensures the contract execution correctness while trivially keeping the data privacy. Moreover, SodsMPC accomplishes the contract business logic privacy while protecting the contract user anonymous identity simultaneously. We express the logic of a contract by a finite state machine (FSM). A state transition of the FSM is represented by a blind polynomial with secret-shared coefficients. When using MPC to compute this blind polynomial, the contract business logic privacy is obtained. These coefficients which control the logic are binary secret shares. We also propose a base conversion method among binary and integer secret shares by MPC. Our contract anonymity comes from the âmixing-then-contractâ paradigm. The online phase of the SodsMPC mixing is a multiplication between a preprocessed permutation matrix and an input vector in the form of secret sharing, which accomplishes a fully randomized shuffle of the inputs and keeps the secret share form for the following contract execution. All SodsMPC components, including a verifiable secret sharing scheme, are quantum-safe, asynchronous, coping with t <; n/3 compromised servers, and robust (tolerates Byzantine servers) in both preprocessing and online phases.
Md. Atik Shahriar, Faisal Haque Bappy, A. K. M. Fakhrul Hossain, Dayamoy Datta Saikat · 7 authors
Blockchain technology has evolved through many changes and modifications, such as smart-contracts since its inception in 2008. The popularity of a blockchain system is due to the fact that it offers a significant security advantage over other traditional systems. However, there have been many attacks in various blockchain systems, exploiting different vulnerabilities and bugs, which caused a significant financial loss. Therefore, it is essential to understand how these attacks in blockchain occur, which vulnerabilities they exploit, and what threats they expose. Another concerning issue in this domain is the recent advancement in the quantum computing field, which imposes a significant threat to the security aspects of many existing secure systems, including blockchain, as they would invalidate many widely-used cryptographic algorithms. Thus, it is important to examine how quantum computing will affect these or other new attacks in the future. In this paper, we explore different vulnerabilities in current blockchain systems and analyse the threats that various theoretical and practical attacks in the blockchain expose. We then model those attacks using Petri nets concerning current systems and future quantum computers.
Edoardo Giusto, Mohammad Ghazi Vakili, Filippo Gandino, Claudio Giovanni Demartini · 5 authors
Recent years have seen the continuous evolution of technology, which has led to the definition of frameworks such as the internet of things (IoT) and Industry 4.0. These paradigms are producing enormous quantities of data every single day. These data are subject to data analysis, shared publicly or kept secret. Traditionally, this task was carried out using databases. With the advent of Blockchain and other distributed ledger technologies (DLTs), instead, these data have a new way of being stored and shared (or kept private). The last actor role in this play is acted by quantum computers, since sufficiently large quantum computers are expected to seriously threaten the security and integrity of DLTs thanks to their totally different way of representing information. This paper aims to investigate the real threats for blockchain due to quantum computing and review post-quantum DLT solutions for traceability applications.
It has been predicted that more devices will be connected to the internet network along with the development of IoT, and that will increase the complexity in the security system. The most important thing in security systems is the process of encryption and authentication. Various encryption techniques are developed to overcome security problems of the data. One of the methods used for authentication of data is Zero Knowledge Proof. This method works to identify the authenticity of someones statement to proof without showing any knowledge of the statement mentioned. This research will mainly discuss about the security of data transmission system by combining data encryption and data authentication. The proposed data encryption is using Advanced Encryption System and method for authentication of data using the Zero Knowledge Proof. This research will conduct the development methods of authentication Zero Knowledge Proof from previous research and the result was compared with the proposed method based on the simulation results transmission system client and server. Experiments will be conducted using thirty-text data, each of data will be measured on the performance of both encryption and authentication process between the previous method and proposed method. Experimental results show the performance of the proposed method has better speed to process application for security of data transmission systems, with performance to authenticate approximately 5 ms from the client side and server side.
Michele Ciampi, Alexandru Cojocaru, Elham Kashefi, Atul Mantri
Secure two-party computation considers the problem of two parties computing a\njoint function of their private inputs without revealing anything beyond the\noutput. In this work, we consider the setting where the two parties (a\nclassical Alice and a quantum Bob) can communicate only via a classical\nchannel. Our first result shows that it is in general impossible to realize a\ntwo-party quantum functionality with black-box simulation in the case of\nmalicious quantum adversaries. In particular, we show that the existence of a\nsecure quantum computing protocol that relies only on classical channels would\ncontradict the quantum no-cloning argument.\n We circumvent this impossibility following three different approaches. The\nfirst is by considering a weaker security notion called one-sided simulation\nsecurity. This notion protects the input of one party (the quantum Bob) in the\nstandard simulation-based sense and protects the privacy of the other party's\ninput (the classical Alice). We show how to realize a protocol that satisfies\nthis notion relying on the learning with errors assumption. The second way to\ncircumvent the impossibility result, while at the same time providing standard\nsimulation-based security also against a malicious Bob, is by assuming that the\nquantum input has an efficient classical representation.\n Finally, we focus our attention on the class of zero-knowledge\nfunctionalities and provide a compiler that takes as input a classical proof of\nquantum knowledge (PoQK) protocol for a QMA relation R and outputs a\nzero-knowledge PoQK for R that can be verified by classical parties. The direct\nimplication of our result is that Mahadev's protocol for classical verification\nof quantum computations (FOCS'18) can be turned into a zero-knowledge proof of\nquantum knowledge with classical verifiers. To the best of our knowledge, we\nare the first to instantiate such a primitive.\n
Amelia Holcomb, Geovandro C. C. F. Pereira, Bhargav Das, Michele Mosca
Hyperledger Fabric is a prominent and flexible solution for building permissioned distributed ledger platforms. Access control and identity management relies on a Membership Service Provider (MSP) whose cryptographic interface only handles standard PKI methods for authentication: RSA and ECDSA classical signatures. Also, MSP-issued credentials may use only one signature scheme, tying the credential-related functions to classical single-signature primitives. RSA and ECDSA are vulnerable to quantum attacks, with an ongoing post-quantum standardization process to identify quantum-safe drop-in replacements. In this paper, we propose a redesign of Fabric's credential-management procedures and related specifications in order to incorporate hybrid digital signatures, protecting against both classical and quantum attacks using one classical and one quantum-safe signature. We create PQFabric, an implementation of Fabric with hybrid signatures that integrates with the Open Quantum Safe (OQS) library. Our implementation offers complete crypto-agility, with the ability to perform live migration to a hybrid quantum-safe blockchain and select any existing OQS signature algorithm for each node. We perform comparative benchmarks of PQFabric with each of the NIST candidates and alternates, revealing that long public keys and signatures lead to an increase in hashing time that is sometimes comparable to the time spent signing or verifying messages itself. This is a new and potentially significant issue in the migration of blockchains to post-quantum signatures.
MOSES DOGONYARO NOEL, Onomza Victor Waziri, Shafiâi Muhammad Abdulhamid, Adebayo Joseph Ojeniyi · 5 authors
The use of public key cryptosystems ranges from securely encrypting bitcoin transactions and creating digital signatures for non-repudiation. The cryptographic systems security of public key depends on the complexity in solving mathematical problems. Quantum computers pose a threat to the current day algorithms used. This research presents analysis of two Hash-based Signature Schemes (MSS and W-OTS) and provides a comparative analysis of them. The comparisons are based on their efficiency as regards to their key generation, signature generation and verification time. These algorithms are compared with two classical algorithms (RSA and ECDSA) used in bitcoin transaction security. The results as shown in table II indicates that RSA key generation takes 0.2012s, signature generation takes 0.0778s and signature verification is 0.0040s. ECDSA key generation is 0.1378s, signature generation takes 0.0187s, and verification time for the signature is 0.0164s. The W-OTS key generation is 0.002s. To generate a signature in W-OTS, it takes 0.001s and verification time for the signature is 0.0002s. Lastly MSS Key generation, signature generation and verification has high values which are 16.290s, 17.474s, and 13.494s respectively. Based on the results, W-OTS is recommended for bitcoin transaction security because of its efficiency and ability to resist quantum computer attacks on the bitcoin network.
Oct 8, 2020·Proceedings of the Twenty-First International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing
This paper explores and suggests possibilities for the design of quantum blockchain systems that are inspired by quantum processing techniques. Quantum states are defined that can be processed either by a physical quantum computer or virtually by emulation on a classical computer where such states can be entangled across different nodes in the system. The collapse of quantum state variables are explored utilizing non-deterministic smart contract processing. A quantum blockchain network is realized with different nodes in the system interacting with each other though a communication network. Different networking use-cases are explored such as to determine which user is given access to a network at a given time, or to select the best access node for a given user.
Johannes Winkler, Andrea Höller, Christian Steger
Picnic is a post-quantum digital signature scheme, where the security is based on the difficulty of inverting a symmetric block cipher and zero-knowledge proofs. However, generating a Picnic signature to a specific message requires up to 300 kB content depending RAM. As the memory of an IoT device is limited this can lead to issues at the implementation. Our target is bringing post-quantum cryptography to IoT systems. We propose three structural adjustments of the Picnic algorithm to reduce the memory usage. Two adjustments are compatible with the reference implementation, one of them breaks backward compatibility. We show analytically that the content depending memory for generating a signature can be decreased to under 10 kB.With these adjustments, Picnic becomes suitable for IoT devices with little RAM. Since our approach also aims at easier parallelization, a speed-up depending on the number of instances is possible.
Cryptocurrencies and distributed registers (blockchains) have recently attracted increased interest among specialists from the widest variety of fields. In turn, the public has generated a pool of regularly asked questions, which have not yet been answered thoroughly. This article provides lines of reasoning with regard to several popular questions linked to this subject. It also addresses issues such as the creation of national cryptocurrencies and use of blockchain technology by businesses and governments. In addition, it analyzes the opinion that cryptocurrencies are a financial pyramid. Finally, it briefly examines the configuration of Bitcoinâs distributed register and looks at how this register could be affected by the hypothetical creation of a quantum computer.
Over the past few years, massive cyberattacks have dominated the public imagination. Most \nAmericans have been directly affected by data breaches and an overwhelming majority believe \nthat they are no longer in control of their data. At the same time, there are important applications in \nwhich the aggregation of private data is unavoidable. Not surprisingly, there has been considerable \ninterest in developing protocols for secure multi-party computation (MPC), i.e., N parties providing \nprivate inputs to jointly compute some function f. Recent developments in MPC have led to leaps \nin efficiency and MPC is quickly becoming a practical approach for privacy-centric distributed \napplications. As MPC applications become deployed, guaranteeing the security of these protocols, \neven when interacting with other applications, is essential. The standard approach to showing \nsecurity of MPC protocols under arbitrary composition is through the universal composability (UC) \nframework. There has been much prior work on this topic; however, most previous work either \nmakes synchronicity assumptions or does not guarantee output delivery in the presence of even \none fault. For practical MPC applications, though, dealing with asynchronicity and robustness is \nessential. In this thesis, we describe two new keywords, eventually and leak, that aid in defining \nprotocols in the asynchronous world and define wrappers that implement these within the UC \nframework. We then use this novel wrapper to give a UC-realization of a reliable broadcast primitive, by means of Brachaâs classic protocol. Finally, we define and prove a realization of what we call the \nsmart contract model of MPC, which serves as a UC-idealization of asynchronous, robust MPC.
Open access
Advancements in Semiconductor Devices and Circuit Design