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The greatest impact blockchain technology has brought to digital security, decentralization , and digitized trust in digital transactions. But as quantum computing develops, blockchain security on its current foundations is at risk. The security of current blockchain systems is largely a product of classical cryptographic algorithms, and these are threatened by the threat of powerful quantum algorithms. With quantum computers coming to fruition, blockchain is not immune to the evolutionary journey it will need to take to reach post-quantum security.
In this article we analyse why existing blockchains might hinder the transition to post-quantum security. The second looks at the technical, economic, and governance-related factors that may well stifle blockchain networks from accommodating quantum-resistant cryptography. It also outlines the necessity of starting to build a future-proof blockchain ecosystem before quantum computers pose a serious threat.
1. Cryptography in Blockchain Security.
The most important feature of blockchain technology is its ability to secure, immutable, and transparent record keeping. This security is heavily reliant on cryptographic techniques such as:
• Public Key Cryptography (PKC): Blockchain networks are secure only because of public key cryptography. It involves a pair of keys: This includes a public key, which is used as an address or identifier, and a private key used to sign transactions. RSA and Elliptic Curve Digital Signature Algorithm (ECDSA) are common public key cryptocurrencies.
• Hashing: In blockchain, more specifically in Bitcoin, cryptographic hash functions (like the SHA-256) are used to ensure data integrity. The input data is transformed by these hash functions to output with fixed size so that the original data cannot be reverse engineered. The blockchain depends on hash functions to link blocks together so that they cannot change and to ensure that the entire network remains consistent.
But the cryptographic algorithms used in blockchain systems, for example RSA and ECDSA, are dependent on problems thought to be hard for classical computers to compute, like number factoring or solving the discrete logarithm problem. However, quantum computers are supposed to be able to solve such problems much faster, destroying the current security model of blockchain.
2. Blockchain threatened by how quantum computing works
Quantum computing makes use of principles of quantum mechanics to process information in ways that classical computers don’t. The most well-known quantum algorithms that pose a threat to cryptography are Shor’s algorithm and Grover’s algorithm:
• Shor’s Algorithm: The integer factorisation and discrete logarithm problems are the main focus to which this quantum algorithm can efficiently solve. Shor’s Algorithm will allow attackers using polynomial time to derive private keys from public keys if they are ever built on large scales.
• Grover’s Algorithm: Compared to Shor’s Algorithm, Grover’s Algorithm is not so impactful, but it could be used to speed up the search process of unsorted databases or finding hash collisions, which can weaken the security of hash algorithms like SHA 256. With the system as purported, it would weaken the integrity of the blockchain’s consensus mechanism and its data integrity.
Although quantum computers capable of executing these algorithms at scale do not yet exist, these quantum threats are hypothetical in that sense. But experts predict it’s only a matter of time before quantum computers will be powerful enough to crack the current cryptographic systems. This poses a strong driver for blockchain systems to relegate to post-quantum cryptography.
3. Classical Cryptography Is Used To Build Current Blockchains
To this day, the current blockchain systems (including Bitcoin and Ethereum) are deeply rooted in classical cryptography. However, ECDSA for digital signatures or any other algorithms used are all inherently susceptible to a quantum computer. The transition to quantum-resistant cryptography is critical, but there are many reasons why current blockchains may be slow to or delay the transition.
a. High Dependence of Them on Existing Cryptographic Algorithms
Public key cryptography is at the heart of blockchain security based on the computational complexity of the factoring large numbers or discrete logarithm problems. If we take a look at public key cryptographic systems like RSA and ECDSA, security is this ‘crucial’ to blockchain networks as it secures data and ensures there is authenticity of data.
The Shor Algorithm can destroy these algorithms; if quantum computers can break them, the security infrastructure of the current blockchain will collapse. Transitioning the blockchain to post-quantum security would require the use of quantum-resistant cryptographic schemes, such as lattice-based cryptography, hash-based signatures, or code-based cryptography. But these new cryptographic methods, for all their sophistication, are also more radically different than the ways we do crypto now and pose significant barriers to their adoption.
b. Modern Blockchains Are Difficult to Change
The native nature of blockchain as a decentralised and immutable platform makes it one of the biggest obstacles to upgrading blockchain networks to quantum-resistant cryptography. Any alteration of the cryptographic infrastructure of the blockchain’s decentralised networks needs to be agreed upon among the majority of the participants, which is to say concluded via a consensus mechanism.
Bitcoin’s value proposition is predicated on the cryptographic infrastructure that supports it. Great coordination between miners, developers, and node operators would be required for a change to the underlying security mechanisms. The typically diverse and dispersed nature of these communities makes consensus on sweeping changes, such as moving to post-quantum cryptography, pretty complex.
Additionally, hard forks altering the cryptographic bedrock of the blockchain are likely to be needed. That being said, they (hard forks) are very divisive and highly contentious within blockchain communities, the Bitcoin Cash and Bitcoin forks being clear examples.
4. Post-Quantum Cryptography: Technical Challenges
Transitioning to post-quantum cryptography presents several technical hurdles that blockchain developers need to overcome:
a. Computational overhead has increased.
Classical crypto algorithms are much less computationally expensive than post-quantum crypto algorithms. For instance, the sizes of keys needed for lattice-based cryptography are higher and more computationally expensive for verifying and transaction signing. If it works out this way, it can encourage slow transaction speeds and higher fees for public blockchain networks with huge user bases.
Efficient and scalable blockchains are built with the idea that adding more complex algorithms will not necessarily make them so. In order to ensure that blockchain systems stay efficient as they move to quantum-resistant algorithms, a great deal of work will need to be done in optimising those algorithms.
b. Higher Storage Requirements and Larger Key Sizes
Classic cryptographic algorithms are generally used with small keys, whereas quantum-resistant algorithms generally need big keys. For instance, key sizes generated from algorithms like NTRU (a lattice-based algorithm) are often orders of magnitude more than what you get from ECDSA or RSA. However, this presents a host of challenges, including higher storage of private and public keys—caused by the increased size of data to be processed—and slower processing times.
In general, such challenges are even more serious in blockchain environments, where nodes across the network need to store and process a large amount of cryptographic data. In such public networks, this can reduce their scalability even further, where already sparse systems are actively experiencing high transaction volumes.
c. Lack of standardization
For post-quantum cryptography presently, there is no consensus for a standard. But the National Institute of Standards and Technology (NIST) is working on standardisation for quantum resistance algorithms, and that’s still ongoing. Without clear standards, blockchain developers are uncertain in choosing the right cryptography to base their blockchains on.
This means different blockchain projects can tinker with various post-quantum cryptographic algorithms, which is fragmentation of the ecosystem. It can also slow the adoption of quantum-resistant technologies, putting at risk new crypto solutions that have not been tested.
5. Economic and Governance Barriers
Beyond technical challenges, there are economic and governance-related factors that might slow the transition to post-quantum security:
a. Incentive Structures and the Participation in Networks
The biggest selling point of blockchain is its being decentralised, or saying no single entity controls this network. This system is one of many where competing interests between participants (such as miners, validators, and developers) can make decision-making slow and complex. Consensus among such a spectrum of participants for a quantum-safe blockchain is not an easy thing to achieve.
For example, they may be reluctant to change the cryptographic infrastructure if it costs them more computations, lowers rewards, or requires more resources. Even with this understanding of quantum attacks, their reluctance could actually slow down the adoption of post-quantum cryptography.
b. Economic Cost of Transition
Making a transition away from quantum security and onto post-quantum security will be a costly and resource-intensive task on blockchain networks. Yet financial and operational resources could strain out blockchain projects with new cryptographic algorithms, hard forks, and new protocols being implemented.
To implement post-quantum cryptographic solutions will be more difficult for smaller blockchain projects, and they will struggle to fund the research and development that is required to do this. This might actually be better attempted for larger projects with more funding and a robust developer community—but even such projects may be reluctant to tackle such a mammoth a task on their own infrastructure.
6. Some Potential Solutions for Making it Easier to Make the Move
While transitioning to post-quantum security is fraught with challenges, several approaches can help facilitate the process:
a. Hybrid Systems
Possible solutions are the creation of hybrid blockchain systems where classical cryptographic algorithms and post-quantum algorithms are mutually combined. These hybrid systems could help the blockchain network maintain compatibility with current systems while maintaining resistance to quantum threats. The idea of a slow transition to full post-quantum security could be easier than a sudden flip.
b. Layered Solutions
A layer approach could be adopted by developers instead of having to change the cryptography underpinning the blockchain completely. For example, one way to mitigate impact on efficiency and user experience would be by utilising quantum-resistant algorithms in certain portions of the blockchain—at transaction signing and wallet security, for example—and continuing to employ traditional algorithms in other portions.
Collaboration and standards development are two of the main reasons.
In the quest for blockchain ecosystem centralisation, the blockchain projects have to coexist and strive to contribute to the creation of common post-quantum cryptography standards. Industry-wide collaboration will facilitate the uptake of secure, standardised solutions that will be universally adopted.
7. Conclusion
Post-quantum blockchain security is an urgent necessity, but existing blockchain systems are negotiating several critical challenges, any of which may slow the transition. All of this hamstrings blockchain networks from adopting quantum-resistant technologies: technical limitations of post-quantum cryptography, reliance on classical cryptographic algorithms, governance issues, and economic barriers.
But as quantum computing evolves, blockchain projects need to be on guard against future threats to their security, proactively. Blockchain technology can implement hybrid models, work with industry standards, and develop quantum-resistant solutions to help the technology navigate the transition to a quantum secure future.
In the end, the pace of this transition will come down to how well the blockchain communities can surmount these challenges and come together to ensure that their networks are kept safe from the inevitable rise of quantum computing.
