Quantum computing, once a theoretical concept, is now quickly advancing and reshaping our understanding of data processing.
Unlike traditional computers using bits, quantum machines leverage qubits, which can exist in multiple states at once. This makes them significantly more efficient than traditional computing systems when tackling complex problems.
For the blockchain sector, the rise of quantum technology poses a significant threat to cryptographic systems that underpin blockchain security. Current encryption methods, such as Rivest-Shamir-Adleman (RSA) and Elliptic-Curve Cryptography (ECC), are widely used in networks like Bitcoin and Ethereum.
Their core strength lies in their complexity, which traditional systems can’t crack. Yet quantum machines claim to be able to break these systems, potentially leaving these networks vulnerable to attacks that were once deemed improbable.
With the entire sector comprising cryptocurrencies, non-fungible tokens (NFTs), and decentralized applications (DApps) at risk, quantum-resistant cryptographic measures are urgently needed. As we slowly move towards the post-quantum era, the blockchain sector must innovate and adapt.
What are quantum computing attacks, and why is it considered a threat to blockchain and cryptocurrencies in general?
Quantum computing attacks are something like current-day brute force attacks in that their capacity to try different combinations is greatly enhanced over classical computers. If you have a combination lock with three digits, there are around a thousand combinations, and a patient thief could try them all and unlock your suitcase or steal your bike. When you have an online password of 12 characters, the permutations increase to 7*10^12 different possible passwords, which a human being couldn’t manage – but a classical computer could try all of them in sequence and eventually find the right combination. If you have a wallet with an encrypted private key, the number of possible options increases to 2^256. This is too many for classical computing to manage, but a quantum computer could do it.
This is a simplification of reality but conveys why a quantum computer attack is a threat to blockchains and cryptocurrencies. Many proposals to address this threat are largely theoretical or depend on new blockchains with native quantum resistance, but this is not practical for existing blockchains. Instead, some researchers focus on end-to-end frameworks that can be applied to existing blockchains. Another potential threat is that quantum computers might mine blocks faster than classical computers, potentially centralizing mining power.
Can the blockchain sector address these issues before quantum computing technology is fully ready?
These are the issues that we see today, but who knows what will emerge once quantum computing is a reality. Blockchain cryptography is evolving to counter these threats, but the biggest question is, what haven’t we thought of? What threats are not obvious today but will emerge once both technologies coexist? We don’t know the answer, but we can be certain of one thing: there will be new and unexpected problems to solve when blockchains encounter quantum computing.
Theoretically, quantum computers can break RSA and Elliptic Curve cryptographic algorithms; how imminent is the threat to current blockchain platforms like Bitcoin and Ethereum?
Quantum cryptography, while promising its potential for breaking existing ciphers, is not ready for practical deployment. On-chain encryption continues to evolve, and cryptographers are aware of the quantum threat. New on-chain encryption methods consider quantum-proof techniques as necessary. Today, there is no imminent threat to Bitcoin or Ethereum because quantum hardware remains largely theoretical.
Do you think cryptographic standards can help secure blockchain networks against quantum threats? Can they be integrated into existing systems like Bitcoin and Ethereum?
Various cryptocurrency algorithms are designed to handle quantum resistance, such as SPHINCS+. While I am chairing a standards committee at IEEE to define best practices in writing quantum algorithms, other working groups at IEEE and other standards organizations are working on best practices for quantum-resistant software development. Blockchains will be able to switch encryption algorithms sooner than many other areas of industry. Chains with governance structures in place will have an easier time making the switch. Chains like Bitcoin or Ethereum may take longer.
What are the challenges decentralized blockchains face in migrating to post-quantum cryptography? Is the pseudonymity inherent with public blockchains an issue?
The pseudonymity of blockchain users is not the issue; it’s the distribution of nodes on each blockchain, of which Bitcoin is the most extreme. Any mitigation strategy to make Bitcoin quantum-proof will almost certainly require a change in the wallet address format. Bitcoin’s proof-of-work consensus mechanism is less threatened, but its address system (based on ECDSA) is vulnerable and will need to change. This has historically been a messy process. Ethereum faces similar challenges with its address structure and wide distribution, but it has an advantage in that it’s more easily upgradable due to its smart contract capabilities.
So, are there any existing blockchain networks equipped for the transition?
Some recently built blockchains have an easier path to mitigation. For example, Cosmos is configured to facilitate easier migration. Chains built on the Cosmos SDK may want to choose a common quantum-proof algorithm to make wallet integration easier. Some chains, such as Secret Network and Fhenix, are designed to encrypt transaction data. Secret uses secure hardware enclaves, such as Intel SGX’s TEE, to protect encrypted data on-chain. These encryptions are resistant to quantum attacks since secure enclaves can change their encryption schemes in real-time, albeit with some performance implications. Fhenix uses fully homomorphic encryption to secure data in a quantum-resistant manner. FHE is not ready for current use, but its timeline is shorter than that of quantum computers, allowing for future blockchain resilience.
How long does the blockchain sector have before the threat of quantum computing becomes inevitable?
By the next 10-20 years, the blockchain industry should be fully prepared. Experts believe that quantum computers capable of breaking current cryptographic systems could emerge in this timeframe. Beyond that, if not addressed, quantum computers will likely break most current cryptographic systems used in blockchains. The day when quantum computing threatens the encryption of Bitcoin and Ethereum is in the uncertain future. Quantum computing estimates range from 2035 to potentially 2050.
