Marcos Allende, Diego López León, Sergio Cerón, Adrián Pareja, Erick Pacheco, Antonio Leal, Marcelo Da Silva, Alejandro Pardo, Duncan Jones, David Worrall, Ben Merriman, Jonathan Gilmore, Nick Kitchener, Salvador Elías Venegas-Andraca
The advent of quantum computing threatens blockchain protocols and networks because they utilize non-quantum resistant cryptographic algorithms. When quantum computers become robust enough to run Shor's algorithm on a large scale, the most used asymmetric algorithms, utilized for digital signatures and message encryption, such as RSA, (EC)DSA, and (EC)DH, will be no longer secure. Quantum computers will be able to break them within a short period of time. Similarly, Grover's algorithm concedes a quadratic advantage for mining blocks in certain consensus protocols such as proof of work. Today, there are hundreds of billions of dollars denominated in cryptocurrencies and other digital assets that rely on blockchain ledgers as well as thousands of blockchain-based applications storing value in blockchain networks. Cryptocurrencies and blockchain-based applications require solutions that guarantee quantum resistance in order to preserve the integrity of data and assets in these public and immutable ledgers. The quantum threat and some potential solutions are well understood and presented in the literature. However, most proposals are theoretical, require large QKD networks, or propose new quantum-resistant blockchain networks to be built from scratch. Our work, which is presented in this paper, is pioneer in proposing an end-to-end framework for post-quantum blockchain networks that can be applied to existing blockchain to achieve quantum-resistance. We have developed an open-source implementation in an Ethereum-based (i.e., EVM compatible) network that can be extended to other existing blockchains. For the implementation we have (i) used quantum entropy to generate post-quantum key pairs, (ii) established post-quantum TLS connections and X.509 certificates to secure the exchange of information between blockchain nodes over the internet without needing a large QKD network, (iii) introduced a post-quantum second signature in transactions using Falcon-512 post-quantum keys, and (iv) developed the first on-chain verification of post-quantum signatures using three different mechanisms that are compared and analyzed: Solidity smart-contracts run by the validators for each transaction, modified EVM Opcode, and precompiled smart contracts.
The advent of quantum computing threatens blockchain protocols and networks because they utilize non-quantum resistant cryptographic algorithms. When quantum computers become robust enough to run Shor's algorithm on a large scale, the most used asymmetric algorithms, utilized for digital signatures and message encryption, such as RSA, (EC)DSA, and (EC)DH, will be no longer secure. Quantum computers will be able to break them within a short period of time. Similarly, Grover's algorithm concedes a quadratic advantage for mining blocks in certain consensus protocols such as proof of work. Today, there are hundreds of billions of dollars denominated in cryptocurrencies and other digital assets that rely on blockchain ledgers as well as thousands of blockchain-based applications storing value in blockchain networks. Cryptocurrencies and blockchain-based applications require solutions that guarantee quantum resistance in order to preserve the integrity of data and assets in these public and immutable ledgers. The quantum threat and some potential solutions are well understood and presented in the literature. However, most proposals are theoretical, require large QKD networks, or propose new quantum-resistant blockchain networks to be built from scratch. Our work, which is presented in this paper, is pioneer in proposing an end-to-end framework for post-quantum blockchain networks that can be applied to existing blockchain to achieve quantum-resistance. We have developed an open-source implementation in an Ethereum-based (i.e., EVM compatible) network that can be extended to other existing blockchains. For the implementation we have (i) used quantum entropy to generate post-quantum key pairs, (ii) established post-quantum TLS connections and X.509 certificates to secure the exchange of information between blockchain nodes over the internet without needing a large QKD network, (iii) introduced a post-quantum second signature in transactions using Falcon-512 post-quantum keys, and (iv) developed the first on-chain verification of post-quantum signatures using three different mechanisms that are compared and analyzed: Solidity smart-contracts run by the validators for each transaction, modified EVM Opcode, and precompiled smart contracts.
This paper describes the work carried out by the Inter-American Development Bank, the IDB Lab, LACChain, Cambridge Quantum Computing (CQC), and Tecnologico de Monterrey to identify and eliminate quantum threats in blockchain networks. The advent of quantum computing threatens internet protocols and blockchain networks because they utilize non-quantum resistant cryptographic algorithms. When quantum computers become robust enough to run Shor's algorithm on a large scale, the most used asymmetric algorithms, utilized for digital signatures and message encryption, such as RSA, (EC)DSA, and (EC)DH, will be no longer secure. Quantum computers will be able to break them within a short period of time. Similarly, Grover's algorithm concedes a quadratic advantage for mining blocks in certain consensus protocols such as proof of work. Today, there are hundreds of billions of dollars denominated in cryptocurrencies that rely on blockchain ledgers as well as the thousands of blockchain-based applications storing value in blockchain networks. Cryptocurrencies and blockchain-based applications require solutions that guarantee quantum resistance in order to preserve the integrity of data and assets in their public and immutable ledgers. We have designed and developed a layer-two solution to secure the exchange of information between blockchain nodes over the internet and introduced a second signature in transactions using post-quantum keys. Our versatile solution can be applied to any blockchain network. In our implementation, quantum entropy was provided via the IronBridge Platform from CQC and we used LACChain Besu as the blockchain network.
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.
Quantum computing's development poses a significant threat to the cryptographic security of current blockchain technologies, potentially undermining the integrity of digital transactions. Quantum computers can break the complex mathematical problems that algorithms like RSA and ECC rely on, which could lead to vulnerabilities such as double-spending and fraud. To address these risks, the blockchain community is exploring quantum-resistant protocols that employ post-quantum cryptographic algorithms, which are designed to withstand quantum computing attacks. Quantum-secure blockchain protocols integrate quantum key distribution (QKD) and post-quantum cryptography (PQC) to enhance security. QKD uses quantum mechanics principles to secure communication channels, ensuring that any attempt to intercept the key introduces detectable anomalies. PQC involves algorithms like lattice-based, hash-based, or multivariate polynomial-based algorithms that are believed to be secure against quantum attacks. These protocols aim to maintain the confidentiality, integrity, and security of data transmitted over the blockchain, ensuring the longevity and reliability of blockchain systems in the face of evolving computational advancements. A quantum-secure blockchain scheme (QSB) utilizes a consensus mechanism, QPoA, and IQS. The QPoA is leveraged for block generation while the IQS is deployed in transaction verification1. Furthermore, the integration of quantum computing with blockchain can address current limitations, such as slow transaction speeds and lack of scalability, by optimizing calculations and enabling smarter, more sophisticated smart contracts. The development and implementation of quantum-resistant blockchains are essential for future-proofing digital transactions and maintaining trust in decentralized systems
The advent of quantum computing has generated apprehensions regarding the viability and security of conventional cryptographic algorithms. These algorithms safeguard the decentralized trust built into the blockchain, which relies on decentralized cryptographic consensus, instead of a central authority. Simultaneously, quantum computing has also unveiled unprecedented possibilities, opportunities and risks in the realm of technology. The significance of this is that numerous sub-routines employed within the blockchain, such as consensus protocols, data transmission, storage, and communication, heavily depend on conventional cryptographic algorithms like Rivest-Shamir-Adleman (RSA) and Elliptic Curve Digital Signature Algorithm (ECDSA). However, these algorithms are susceptible to quantum algorithms, which have the potential to effectively compromise them once quantum computers with sufficient computational capabilities are developed. Blockchain, although primarily recognized for its association with cryptocurrencies, is essentially a decentralized and trustless distributed ledger system. Its purpose is to enable decentralized communication, coordination, and the attainment of desired objectives through consensus mechanisms. A notable illustration of this concept is a blockchain transaction. The advent of quantum computing poses a significant threat to the security of blockchain systems, as the asymmetric algorithms employed within their many components will likely become obsolete. This jeopardizes the integrity of the blockchain system, which underpins a multi-billion dollar economy reliant on its inherent transparency and safety. This paper seeks to present an overview of the various threats faced by blockchain systems, examine the potential of quantum algorithms in offering cryptographic signatures for these systems, and provide a broad perspective on how to protect blockchain systems from quantum threats by utilizing quantum algorithms for cryptographic signatures. This study enhances the comprehension of existing vulnerabilities in blockchain systems, specifically focusing on the potential risks posed by quantum computing. Additionally, it sheds light on the ongoing efforts within the industry and current research endeavors aimed at addressing these weaknesses.
This paper examines the growing threat that quantum computing presents to blockchain security. Core blockchain cryptographic frameworks, specifically the Elliptic Curve Digital Signature Algorithm and the Secure Hash Algorithm 256, are vulnerable to quantum algorithms. Both the Shor algorithm and the Grover algorithm are capable of breaking the Elliptic Curve Digital Signature Algorithm, enabling attackers to calculate private keys from public keys, while the Grover algorithm can also compromise hash-based systems that depend on brute-force methods, such as Proof-of-Work. On-chain analysis indicates that billions of dollars’ worth of crypto-assets are held in addresses susceptible to these quantum attacks. A proposed countermeasure is migration to Post-Quantum Cryptography, which incorporates quantum-resistant algorithms, such as CRYSTALS-Dilithium and Falcon. However, this migration introduces a trilemma among network security, decentralization, and performance. Post-Quantum Cryptography algorithms significantly increase transaction sizes and computational costs, which pose economic and technical challenges for large blockchain networks. The paper further discusses how the timeline for quantum advancements will be shaped by geopolitical competition, and how the catch-the-crop, decrypt-later strategy puts current data at risk from future quantum decryption. It emphasizes that active migration to Post-Quantum Cryptography is urgent, calling on stakeholders to prioritize system audits, transition to cryptographically flexible infrastructures, promote research into quantum-resistant solutions, and establish governance frameworks that enable prompt and decentralized upgrades.
The concept of blockchain technology has transformed the digital ecosystem to allow decentralized, transparent and immutable transactions in various sectors. Its security is closely dependent on classical cryptography like ECDSA and RSA to perform digital signatures and SHA-256 to achieve consensus, which are becoming more susceptible to quantum computing. The cryptographic principles underpinning blockchain could be compromised with the emergence of the quantum algorithms of Shor and Grover, endangering the integrity of transactions, authentication and consensus protocols. This paper discusses the implications that quantum computing could have on blockchain security, analyses vulnerabilities of current cryptographic primitives and assesses post-quantum cryptographic (PQC) protocols, including lattice-based protocols, hash-based protocols, and code-based protocols. To guarantee backwards compatibility, as well as a gradual upgrade process to quantum-resistant protocols, a hybrid migration approach that involves transactions with two signatures is suggested. Experimental analysis shows that PQC integration attains reasonable performance trade-offs, that preserve verification costs, block size growth, and throughput effects within feasible limits, and that zero-loss resilience is achieved during reorganization tests. The conclusion is that blockchains with PQC support can reach post-quantum levels of security without major operation interruption, and they provide a viable roadmap to moving towards distributed ledger systems that are future-ready.