Most blockchain solutions are susceptible to quantum attackers as they rely on cryptography that is known to be insecure in the presence of quantum adversaries. In this work we advance the study of quantum-resistant blockchain solutions by giving a quantum-resistant construction of a deterministic wallet scheme. Deterministic wallets are frequently used in practice in order to secure funds by storing the sensitive secret key on a so-called cold wallet that is not connected to the Internet. Recently, Das et al. (CCS'19) developed a formal model for the security analysis of deterministic wallets and proposed a generic construction from certain types of signature schemes that exhibit key rerandomization properties. We revisit the proposed classical construction in the presence of quantum adversaries and obtain the following results.
Most blockchain solutions are susceptible to quantum attackers as they rely on cryptography that is known to be insecure in the presence of quantum adversaries. In this work we advance the study of quantum-resistant blockchain solutions by giving a quantum-resistant construction of a deterministic wallet scheme. Deterministic wallets are frequently used in practice in order to secure funds by storing the sensitive secret key on a so-called cold wallet that is not connected to the Internet. Recently, Das et al. (CCS'19) developed a formal model for the security analysis of deterministic wallets and proposed a generic construction from certain types of signature schemes that exhibit key rerandomization properties. We revisit the proposed classical construction in the presence of quantum adversaries and obtain the following results.
Cryptocurrency networks crucially rely on digital signature schemes, which are used as an authentication mechanism for transactions. Unfortunately, most major cryptocurrencies today, including Bit-coin and Ethereum, employ signature schemes that are susceptible to quantum adversaries, i.e., an adversary with access to a quantum computer can forge signatures and thereby spend coins of honest users. In cryptocurrency networks, signature schemes are typically not executed in isolation, but within a so-called cryptographic wallet. In order to achieve security against quantum adversaries, the signature scheme and the cryptographic wallet must withstand quantum attacks.
Abstract Since the advent of Bitcoin, cryptocurrencies have gained substantial popularity, and crypto wallets have evolved into the predominant tool for safeguarding and managing cryptographic keys to access cryptocurrency funds. Deterministic wallets are proposed as an advanced wallet mechanism to provide benefits such as low-maintenance, easy backup and recovery, and support for functionalities required by cryptocurrencies. Alkeilani Alkadri et al. (ACM CCS’20) presented the first post-quantum secure deterministic wallet scheme, but it exhibits a gap to bridge before achieving practical applicability, as reflected in both their concrete parameters size and computational efficiency. In this paper, we propose an efficient post-quantum secure deterministic wallet scheme. In particular, we present a new construction method for deterministic wallets, prove the security in the quantum random oracle model, and provide an efficient instantiation. The comparison result, with the work of Alkeilani Alkadri et al. (ACM CCS’20), shows our work has a comprehensive improvement on efficiency, e.g., the pk size is ≈40.7 ≈ 40.7 times shorter, sk is ≈9.2 ≈ 9.2 times shorter, and the signing time is ≈3.1 ≈ 3.1 times faster.
The fast growth of quantum computing makes the old modes of cryptography, be it RSA or ECC, weak to quantum attacks, especially when it employs Shor's algorithm. Threatening also builds up on the post-quantum age regarding blockchain technology and its external cryptography, which secures reliable transactions and authentication. This study will address the importance of quantum resistant blockchain authentication protocols for the security of decentralized systems against any forward-looking quantum-enabled attacks. This paper goes through different classifications of post-quantum cryptography like lattice-based, hash-based, multivariate polynomial, and code-based cryptography, taking an effort to analyze their compatibility with blockchain use cases.[8] Moreover, we also introduce the innovative quantum-resistant authentication model designed to enhance security while not compromising upon efficiency.[2] [3] Our proposed model would ensure scalability and less computational overhead by partially providing immunity to quantum adversaries through its underlying use of post-quantum signature schemes and lightweight key exchange mechanisms. This research aims at laying the foundation for developing a secure blockchain ecosystem against quantum threats, heading toward a resistant future-proof decentralized infrastructure. [4] [5]
We call quantum security the area of IT security dealing with scenarios where one or more parties have access to quantum hardware. This encompasses both the fields of post-quantum cryptography (that is, traditional cryptography engineered to be resistant against quantum adversaries), and quantum cryptography (that is, security protocols designed to be natively run on a quantum infrastructure, such as quantum key distribution). Moreover, there exist also hybrid models, where traditional cryptographic schemes are somehow `mixed' with quantum operations in certain scenarios. Even if a fully-fledged, scalable quantum computer has yet to be built, recent results and the pace of research in its realization call for attention, lest we suddenly find ourselves one day with an obsolete security infrastructure. For this reason, in the last two decades research in quantum security has experienced an exponential growth in interest and investments. In this work, we propose the first systematic classification of quantum security scenarios, and for each of them we recall the main tools and results, as well as presenting new ones. We achieve this goal by identifying four distinct quantum security classes, or domains, each of them encompassing the security notions and constructions related to a particular scenario. We start with the class QS0, which is `classical cryptography' (meaning that no quantum scenario is considered), where we present some classical constructions and results as a preliminary step. Regarding post-quantum cryptography, we introduce the class QS1, where we discuss in detail the problems arising when designing a classical cryptographic object meant to be resistant against adversaries with local quantum computing power, and we provide a classification of the possible quantum security reductions in this scenario when considering provable security. Moreover, we present results about the quantum security and insecurity of the Fiat-Shamir transformation (a useful tool used to turn interactive identification schemes into digital signatures), and ORAMs (protocols used to outsource a database in a private way). In respect to hybrid classical-quantum models, in the security class QS2 we discuss in detail the possible scenarios where these scenarios arise, and what a correct formalization should be in terms of quantum oracle access. We also provide a novel framework for the quantum security (both in terms of indistinguishability and semantic security) of secret-key encryption schemes, and we give explicit secure constructions, as well as impossibility results. Finally, in the class QS3 we consider all those cryptographic constructions designed to run natively on quantum hardware. We give constructions for quantum encryption schemes (both in the secret- and public-key scenario), and we introduce transformations for obtaining such schemes by conceptually simpler schemes from the class QS2. Moreover, we introduce a quantum version of ORAM, called quantum ORAM (QORAM), aimed at outsourcing in a private way a database composed of quantum data. In proposing a suitable security model and an explicit construction for QORAMs, we also introduce a technique of independent interest which models a quantum adversary able to extract information from a quantum system without disturbing it `too much'. We believe that the framework we introduce in this work will be a valuable tool for the scientific community in addressing the challenges arising when formalizing sound constructions and notions of security in the quantum world.
The emergence of quantum computing poses a significant threat to the security of blockchain protocols, primarily due to the vulnerability of current cryptographic algorithms to quantum attacks. This vulnerability jeopardizes the integrity of data and assets stored on blockchain networks, which currently hold hundreds of billions of dollars in cryptocurrencies and other digital assets. To mitigate this risk, various proposals and solutions have been presented in the literature. However, most existing proposals are either theoretical, rely on large quantum key distribution (QKD) networks, or advocate for the development of new quantumresistant blockchain networks from scratch. Despite the understanding of the quantum threat and potential solutions, practical implementations are scarce. A recent survey paper addresses this gap by proposing an end-to-end framework for achieving postquantum resistance in existing blockchain networks. The framework, outlined in the survey, is compatible with Ethereum-based networks and offers practical solutions for key generation, secure communication between nodes, and transaction verification. Notably, the framework utilizes quantum entropy for key generation, and post-quantum TLS connections, and introduces post-quantum signatures in transactions. Additionally, it incorporates on-chain verification mechanisms using Solidity smart contracts and modified EVM Opcode. This chapter represents a significant contribution to the field by providing a comprehensive overview of existing solutions and proposing a practical framework for enhancing blockchain security against quantum threats.
The integration of blockchain technology with almost all sectors can bring positive transformation and a future influence on digital transactions. So far as the development of quantum computers has been achieved, it's necessary for blockchain security to explore quantum-resistant cryptographic techniques. This study inspects the production of a blockchain system with an adjustable transaction payment model, and introduces quantum resistant cryptography. Basically, the system attempts to compensate for the inherent security flaws in each of the conventional blockchains by authenticating and verifying transactions using Hash-based Message Authentication Code (HMAC)-based signatures, using conventional quantum-safe digital wallets. The project also looks at a dynamic fee setting to optimize transaction processing during periods of network congestion and a Proof-of-Work (PoW) consensus mechanism to lock the blockchain further. Finally, This paper would simulate the E91 quantum key distribution (QKD) protocol so as to examine the security features that are provided by the entanglement effects. Unlike the more commonly employed BB84 scoring system, the E91 scheme involves the discovery of eavesdropping through the breach of Bell inequality, and thus provides a unique approach to modular authentication of key swap in decentralized environment.