Post quantum blockchain
Enterprise Applications. Blockchains have taken the world by storm because they have taken cyber security to a new height. While blockchains are poised to disrupt many industries, from their operations to business models, quantum computing is poised to disrupt virtually the whole cyber security as we know today, including blockchains. Its security is based on the complexity of computation. It takes a very long time much longer than an average human life span to crack such a mechanism even when using a super computer. Some critics believe quantum computers are a fiction and will always be.
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Content:
- The Collapse of Cryptography? Considering the quantum threat to blockchain
- Think openly, build securely
- NIST Post Quantum Crypto timelines: avoiding the dangerous misconception
- Build a custom email digest by following topics, people, and firms published on JD Supra.
- Will quantum computing impact the blockchain space?
- Resistant Blockchain Cryptography to Quantum Computing Attacks
- NIST previews post-quantum cryptography challenges
- Computer Security Resource Center
The Collapse of Cryptography? Considering the quantum threat to blockchain
Received December 24, , accepted January 18, , date of publication January 23, , date of current version February 4, Digital Object Identifier Corresponding authors: Tiago M. In the case of blockchain, such characteristics are provided through public-key cryptography and hash functions.
Such algorithms threaten both public-key cryptography and hash functions, forcing to redesign blockchains to make use of cryptosystems that withstand quantum attacks, thus creating which are known as post-quantum, quantum-proof, quantum-safe or quantum-resistant cryptosystems. For such a purpose, this article first studies current state of the art on post-quantum cryptosystems and how they can be applied to blockchains and DLTs. Moreover, the most relevant post-quantum blockchain systems are studied, as well as their main challenges.
Furthermore, extensive comparisons are provided on the characteristics and performance of the most promising post-quantum public-key encryption and digital signature schemes for blockchains. Thus, this article seeks to provide a broad view and useful guidelines on post-quantum blockchain security to future blockchain researchers and developers.
Blockchain is a technology that was born with the cryptocur-rency Bitcoin [1] and that is able to provide secure com-munications, data privacy, resilience and transparency [2]. A blockchain acts as a distributed ledger based on a chain of data blocks linked by hashes that allow for sharing infor-mation among peers that do not necessarily trust each other, thus providing a solution for the double-spending problem [3]—[5].
Such features have popularized blockchain in the last years and it has already been suggested as a key technology for different applications related to smart health [6], mea-suring systems [7], logistics [8], [9], e-voting [10] or smart factories [11], [12]. Hash functions are also key in a blockchain, since they allow for generating dig-ital signatures and for linking the blocks of a blockchain.
The problem is that both public-key cryptosystems and hash func-tions are threatened by the evolution of quantum computers. In the case of public-key cryptosystems, secure transaction data may be recovered fast by future quantum computing attacks.
This article analyzes how to evolve blockchain cryptogra-phy i. To guide researchers on the development of such a kind of blockchains, this article first provides a broad view on the current state of the art of post-quantum cryptosystems.
Specifically, the most relevant post-quantum cryptosystems for blockchains are analyzed, as well as their main challenges. Furthermore, extensive com-parisons are provided on the characteristics and performance of the most promising post-quantum public-key encryption and digital signature schemes. The rest of this article is structured as follows. SectionII describes the essential concepts related to blockchain and to its security primitives.
Section III studies the impact of quantum attacks on blockchain public-key security schemes and on the most popular hash functions. In addition, SectionIIIenumerates the most relevant post-quantum initia-tives, emphasizing the ones related to blockchain and indicat-ing the main features that a blockchain post-quantum scheme would need to provide.
Section IVreviews the main types of post-quantum public-key and digital signature schemes, and analyzes their application to blockchain. SectionV stud-ies the performance of the most promising post-quantum cryptosystems when running them on hardware that can be used by blockchain nodes. Section VI details the main blockchain proposals that have already considered the use of post-quantum schemes.
SectionVIIindicates the most signif-icant challenges currently posed by post-quantum blockchain schemes and points at different paths to be followed by future researchers and developers. Before starting to review the state of the art on post-quantum blockchains i.
It is first important to note that the concept of blockchain has evolved significantly since its original definition for Bit-coin [1]. In fact, researchers are still discussing the different elements that a blockchain has to contemplate to be actu-ally considered a blockchain. The most common definition of blockchain is the one given in the Introduction of this article: it is a public ledger that stores data e.
Every trans-action on the blockchain is verified and stored by following a consensus protocol. Once a transaction is stored, ideally, it cannot be removed from the blockchain without making a significant computational effort.
A blockchain node is a computational entity able to per-form operations on the blockchain. It is common to distin-guish between regular blockchain nodes, which only interact with the blockchain, and full nodes, which have a copy of the blockchain and contribute to it by validating transactions. A blockchain miner is a third type of node that is present in many blockchains and whose contribution is essential during blockchain transaction validations: to carry out the validation, they perform certain actions following a consensus proto-col.
The concept of smart contract is also relevant: it is a piece of code stored on the blockchain that can be executed autonomously. Smart contracts can be used to automate cer-tain tasks depending on the state of the blockchain and in other external data sources called oracles [22]. The previously introduced concepts have contributed to the success of blockchain and to its main security features:.
Blockchain uses public-key cryptography and hash functions for providing data pri-vacy, integrity and authentication. A detailed description on the inner workings of the pre-viously mentioned blockchain components and algorithms is out of the scope of this paper, but the interested reader can find further information in [2], [22]—[28].
For instance, Bitcoin uses ECDSA signatures with the Koblitz curve secpk1, which depends on a private key for signing messages and on the corresponding public key for checking the signature. Public-key cryptography is also essential for the so-called wallets, which are private key containers that store files and simple data.
Thus, in a blockchain system each user has a wallet that is associated with at least a public address usually a hash of the user public key and a private key that the user needs for signing transactions. In order to spend bitcoins, their owner has to demonstrate the ownership of a private key. To verify the authenticity of the received currency, every entity that receives bitcoins verifies its digital signature by using the public key of the sender.
Hash functions like SHA or Scrypt are commonly used by blockchains because they are easy to check, but really difficult to forge, thus allowing the generation of digital signatures that blockchain users need to authenticate them-selves or their data transactions in front of others.
Hash functions are also used by blockchains to link their blocks i. Such blocks are linked in chronological order, containing each block the hash of the previous block. It is straightforward to hash a block of a blockchain, but some blockchains like Bitcoin restrict block hashing to make it meet a specific mathematical condition e. Finally, it is worth mentioning that hash functions are used in blockchains for generating user addresses i.
It must be first noted that public-key cryptosystems strength against classical computing attacks has been traditionally estimated through the so-called bits-of-security level. Such a level is defined as the effort required by a classical computer to perform a brute-force attack.
For instance, an asymmetric cryptosystem has a bit security when the effort required to attack it with a classical computer is similar to the one needed to carry out a brute-force attack on a bit cryp-tographic key. As a reference, Table1indicates the security level of some of the most popular symmetric and asymmetric cryptosystems.
TABLE 1. Reference security levels for popular symmetric and asymmetric cryptosystems source: [31]. The cost of breaking current bit security cryptosystems with classical computers is estimated to be between tens of thousands and hundreds of millions of dollars. In the case of bit cryptosystems, they are considered to be secure to classical computing attacks for the next 30 to 40 years [32].
However, researchers have determined that bit elliptic curves can be broken with a qubit quantum computer, while bit RSA would need roughly 2, qubits [33]. Such a threat affects not only cryptosystems that rely on inte-ger factorization e. As of writing, powerful quantum computers are not avail-able: the most powerful quantum computer claimed by IonQ has only 79 qubits and even technologically-advanced orga-nizations like the U.
National Security Agency NSA seem to have not made significant progress on large quan-tum computers [35]. However, it is estimated that in the next 20 years such a kind of computers will be functional enough to be able to break easily current strong public-key cryptosystems [36]. In fact, organizations like the NSA have already warned on the impact of quantum computing on IT products and recommended increasing the ECC Elliptic Curve Cryptography security level of certain cryptographic suites [34].
Although some researchers have speculated on the real reasons behind such an NSA announcement [37], long-term public-key cryptography seems to be threatened and developers need to prepare current blockchains for the post-quantum era.
Table 2 indicates the main characteristics of the most relevant public-key cryptosystems that are affected by the quantum threat. In contrast to public-key cryptosystems, traditional hash functions are considered to be able to withstand quantum attacks since it seems unlikely the development of quan-tum algorithms for NP-hard problems [38]. Although new hash functions have been recently proposed by academics to resist quantum attacks [39], it is usually recommended to increase the output size of traditional hash functions.
Such a conclusion means that many current hash functions would not be valid for the post-quantum era, while others like SHA-2 or SHA-3 will have to increase their output size. As a reference, Table2 includes the main characteristics of the most popular hash functions that are currently used by relevant blockchains and indicates the impact of quantum computing on their security level. Post-quantum cryptography is currently a hot topic that has been addressed by research projects e.
Among the previously mentioned initiatives, it is worth noting the NIST call for proposals for post-quantum public-key cryptosystems [66], which is currently in its sec-ond round [67] and which is expected to deliver the first standard drafts between and In order to be efficient, a post-quantum cryptosystem would need to provide blockchains with the following main features:.
In addition, small keys involve less com-plex computational operations when managing them. This is especially important for blockchains that require the interaction of Internet of Things IoT end-devices, which are usually constrained in terms of storage and computational power.
It is worth indicating that IoT, like other emerging technologies e. Post-quantum schemes need to be as fast as possible in order to allow a blockchain to process a large amount of transactions per second. Moreover, a fast execution usually involves low computational complex-ity, which is necessary to not to exclude resource-constrained devices from blockchain transactions. For instance, some schemes can be executed fast in Intel microprocessors that make use of the Advanced Vector Extensions 2 AVX2 instruction set, but the same schemes may be qualified as slow when executed on ARM-based microcontrollers.
Therefore, it is necessary to look for a trade-off between computational complex-ity, execution time and supported hardware devices. Bit-coin are considered to be power hungry mainly due to the energy required to execute its consensus protocol. There are other factors that impact power consumption, like the used hardware, the amount of performed commu-nications transactions and, obviously, the implemented security schemes, which can draw a relevant amount of current due to the complexity of the performed opera-tions [83], [84].
There are four main types of post-quantum cryptosystems and a fifth kind that actually mixes both pre-quantum and. A detailed description on the algorithms cited in the next subsections is out of the scope of this article, but the interested reader can consult the specific references cited throughout the text and books like [85], which provide a wide but comprehensive description of the most popular post-quantum cryptosystems.
They are essentially based on the theory that supports error-correction codes. Such matrices usually occupy between kilobytes and several megabytes, which may be a restriction when resource-constrained devices are involved.
To tackle this issue, future researchers will have to study matrix compression tech-niques, as well as the use of different codes e. As a reference, Table3 compares the main characteris-tics of the public-key code-based post-quantum encryption cryptosystems that passed to the second round of the NIST call. There are other post-quantum cryptosystems [89], but the NIST second-round candidates are specially interest-ing due to their standardization chances and because they have been already thoroughly analyzed by the cryptographic community.
Specifically, the cryptosystems of the Table were selected with the objective of comparing the ones with the smallest key sizes that provided the main quantum security levels demanded by NIST , and bits. The same criteria were applied for the selection of the algo-rithms compared in the rest of this article. As it can be observed in Table3, the evaluated code-based cryptographic schemes provide between and bits of classical security, but such a level is reduced signifi-cantly in terms of quantum security.
Regarding the compared. Post-quantum public-key cryptosystem taxonomy and main practical implementations. On average, even when making use of com-pression techniques, the size of code-based scheme keys is clearly larger than the one required by current ECDSA and RSA-based encryption systems. It is worth pointing out that in the case of HQC two key sizes are indicated: the one inside parentheses is related to the use of a seed expander.
However, note that during the execution of the algorithm an expanded key will consume the amount of memory indicated outside the parentheses and will also need to perform the expansion operation, which slows down the execution of the algorithm. Overall, among the schemes compared in Table3, it seems that RQC-II provides the best trade-off between security and key size, although it is not among the fastest post-quantum schemes the performance of the algorithms in Table 3 is analyzed later in SectionV.
Think openly, build securely
The goal is to create standards for new asymmetric encryption algorithms capable of withstanding attacks from Quantum Computers. NIST started this process started in and has stated that fully published standards will be available in Rolling out these new algorithms across the entire ecosystem and supply chain will take years. With NIST standards expected in , some assume that we must wait until to begin implementing post quantum crypto solutions. This is a misconception. NIST has stated that they plan to announce the algorithms to be standardized in December of or January of
NIST Post Quantum Crypto timelines: avoiding the dangerous misconception
Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions. Towards Post-Quantum Blockchain: A Review on Blockchain Cryptography Resistant to Quantum Computing Attacks Abstract: Blockchain and other Distributed Ledger Technologies DLTs have evolved significantly in the last years and their use has been suggested for numerous applications due to their ability to provide transparency, redundancy and accountability. In the case of blockchain, such characteristics are provided through public-key cryptography and hash functions. However, the fast progress of quantum computing has opened the possibility of performing attacks based on Grover's and Shor's algorithms in the near future. Such algorithms threaten both public-key cryptography and hash functions, forcing to redesign blockchains to make use of cryptosystems that withstand quantum attacks, thus creating which are known as post-quantum, quantum-proof, quantum-safe or quantum-resistant cryptosystems.
Build a custom email digest by following topics, people, and firms published on JD Supra.
Received December 24, , accepted January 18, , date of publication January 23, , date of current version February 4, Digital Object Identifier Corresponding authors: Tiago M. In the case of blockchain, such characteristics are provided through public-key cryptography and hash functions. Such algorithms threaten both public-key cryptography and hash functions, forcing to redesign blockchains to make use of cryptosystems that withstand quantum attacks, thus creating which are known as post-quantum, quantum-proof, quantum-safe or quantum-resistant cryptosystems.
Will quantum computing impact the blockchain space?
Our team of world-leading cryptographers and engineers authored the only remaining finalist algorithm in the code-based category of the NIST Post-Quantum Cryptography Standardisation competition, which is defining the future global standard of public-key cryptography. This ecosystem protects data from the moment it is created, when it is stored and as it is transferred, as well as securing organisations from adjacent risks like quantum identity attacks. We have been working to protect the world from the risk of quantum attack since and our committed team has been involved with many of the first real-world quantum-safe projects. No matter the industry you operate in, we can help you to deliver solutions that protect your data and assets from quantum attack. Anywhere that your organisation relies on cryptography provides an opportunity to prepare for the quantum era. Our customers include:.
Resistant Blockchain Cryptography to Quantum Computing Attacks
This item in japanese. Apr 22, 4 min read. Sergio De Simone. While quantum computing is still in its infancy , post-quantum cryptography is a field of growing interest for companies and research institutions. InfoQ has spoken with cryptography researcher Jean-Philippe Aumasson to understand where post-quantum crypto is headed. Jean-Philippe Aumasson : I've been doing cryptography since , when I started publishing research at international conferences. Since that I've done a PhD in crypto, worked in a big technology firm, did consulting and audit, and created start-ups. I'm currently co-founder and chief security officer of Taurus , now the leading European provider of crypto asset custody technology for banks.
NIST previews post-quantum cryptography challenges
What does it really mean to data protection? Is it really the end of encryption as we know it? It does not give you more processing power, instead it relies on superposition ability to be in multiple states at the same time and entanglement the perfect unison of two or more quantum particles to process large quantities of information including numbers. The first real use for quantum computers will likely be for advancements in areas such as material design, pharmaceuticals, and optimizing the power grid.
Computer Security Resource Center
Quantum Computers in a few years will be a threat for currently used blockchains. The implementation of Post quantum Cryptography to current blockchains has small chances. Post quantum cryptography is problematic to apply because of the speed of PQC methods and large sizes of public key and signatures, which limits scaling of blockchains based on PQC. In Rainbow we resolve the above issue by using a proprietary blockchain solution. Prototype version is a simple one blockchain. Rainbow — Post Quantum Blockchain Abstract: Quantum Computers in a few years will be a threat for currently used blockchains.
In our paper March of the Blocks we commented on the substantial compliance hurdles that the General Data Protection Regulation GDPR presents to the ongoing development of blockchain solutions that involve storing and transacting with data. There, we concluded that blockchain solutions that respect the fundamental principles of data protection and privacy are achievable. But does our conclusion hold firm in light of the threat posed by quantum technology to the integrity of data recorded on a blockchain? In this article, with help from the team at our Quantum Computing Hub, we revisit our thinking and interrogate whether quantum computers herald the end of data security in the context of blockchain solutions, or whether the reality is in fact more nuanced. Simply put, quantum computers are computers that make use of two laws of quantum mechanics: superposition and entanglement. This is easiest to explain by reference to classical computers the computers we currently use which make use of bits, units of information which can only exist in one of two states: off or on, 0 or 1.
The threat of quantum computing to cryptography is real. During Bitcoin Wednesday on 3 April, , Jin Liu, the Chairman of ABCMint, will talk about the growing risk, including the state of the art in quantum-resistant blockchain tech and what the industry will have to do to implement it successfully. NSA believes that the external cryptographic community can develop quantum resistant algorithms and reach broad agreement for standardization within a few years….
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