Quantum computing's threat to blockchain security, says expert

Quantum computing, once a theoretical concept, is now advancing rapidly and transforming our understanding of data processing.

Unlike traditional computers that use bits, quantum machines take advantage of qubits, which can exist in multiple states at once. This makes them significantly more efficient than traditional computing systems when it comes to tackling complex problems.

For the blockchain industry, the rise of quantum technology poses a significant threat to the 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 such as bitcoin and ethereum.

Their main strength lies in their complexity, which traditional systems cannot decipher. However, quantum machines claim to be able to decipher these systems, which could leave these networks vulnerable to attacks that were previously considered unlikely.

With the entire industry comprising cryptocurrencies, non-fungible tokens (nfts) and decentralized applications (DApps) at risk, quantum-resistant cryptographic measures are urgently needed. As we slowly move into the post-quantum era, the blockchain industry must innovate and adapt.

To shed light on these issues, Lisa Loud, Executive Director of the Secret Network Foundation and Chair of the IEEE SA Quantum Algorithms Working Group, recently spoke to crypto.news and discussed the implications of quantum computing for blockchain security and how these threats are being addressed.

What are quantum computing attacks and why are they considered a threat to blockchain and cryptocurrencies in general?

Quantum computing attacks are a bit like today’s brute-force attacks, in that their ability to try different combinations is much greater than that of classical computers. If you have a three-digit combination lock, there are about a thousand combinations, and a patient thief could try them all and unlock your suitcase or steal your bike. When you have a 12-character online password, the permutations increase to 7,212 different possible passwords, which a human couldn’t handle, but a classical computer could try them all 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 much for classical computing to handle, but a quantum computer could.

This is a simplification of reality, but it conveys the concept of why a quantum computing attack is a threat to blockchains and cryptocurrencies. Many proposals to address this threat are largely theoretical or rely on the solution of creating new blockchains with native quantum resistance, but this is not practical when there are millions of dollars tied up in existing blockchains. Instead, some researchers are focusing on end-to-end frameworks that can be applied to existing blockchains. Another less obvious but potential threat is that quantum computers might be able to mine blocks much 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 problems we see today, but who knows what will emerge once quantum computing is a reality. We know that blockchain cryptography is evolving specifically to counter these threats, but the bigger question is: what haven’t we thought of? What threats exist that aren’t obvious today but will only emerge once we have these two technologies in the same space? We don’t know the answer, but we can be sure of one thing: there will be new and unexpected problems to solve when blockchains meet quantum computing.

In theory, quantum computers can break RSA and Elliptic Curve cryptographic algorithms; how imminent is the threat to current blockchain platforms like bitcoin and ethereum?

The field of quantum cryptography, while promising in its potential to crack existing codes, is far from ready for practical implementation. At the same time, on-chain encryption continues to evolve and today’s cryptographers are aware of the looming quantum threat. As a result of this set of conditions, the development of new on-chain encryption methods deems quantum-proof methods necessary. Today, there is no imminent threat to bitcoin or ethereum simply because quantum hardware is still largely a theoretical construct.

Do you think cryptographic standards can help protect blockchain networks against quantum threats? Can they be integrated into existing systems like bitcoin and ethereum?

There are several cryptocurrency algorithms designed to handle quantum resistance, such as SPHINCS+. While I chair a standards committee at the IEEE to define best practices for writing quantum algorithms, there are other working groups at the IEEE and many other standards organizations working on best practices for developing quantum-resistant software. Blockchains will be able to change encryption algorithms sooner than many other areas of the industry. In particular, chains that have an established governance structure will have an easier time making the change. Chains like bitcoin or ethereum may take longer.

What are the challenges facing decentralized blockchains in migrating to post-quantum cryptography? Is the pseudonymity inherent in public blockchains a problem?

The pseudonymity of blockchain users is not the issue here, but rather 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 to the wallet address format. bitcoin’s proof-of-work consensus mechanism is less immediately threatened, but its address system (based on ECDSA – Elliptic Curve Digital Signature Algorithm) is vulnerable and will need to change. This has historically been a messy process that created chaos and some losses. ethereum faces similar challenges with its address structure and wide distribution, but has the advantage of being easier to upgrade than bitcoin due to its smart contract capabilities.

So yes, there will be challenges in migrating any blockchain to post-quantum cryptography, and the more widely distributed the chain is, the harder these will be to overcome. Wallets that migrate more slowly may face greater vulnerabilities to quantum attacks. Ensuring that post-quantum systems can interact with legacy systems during the transition period will require maintaining dual systems for an extended period, and the larger key structure may impact blockchain performance.

So are there existing blockchain networks equipped for the transition?

Some blockchains that were built more recently have an easier path to mitigation. For example, Cosmos is set up in a way that would lend itself to easier migration. All chains built on the Cosmos SDK may want to choose a common quantum-proof algorithm to make wallet integration easier. Some chains are specifically designed to encrypt the data they carry in transactions, such as Secret Network and Fhenix. Secret uses secure hardware enclaves (such as Intel SGX TEEs) to protect encrypted data on-chain. These ciphers are resistant to quantum attacks, as it is possible for the secure enclaves to change their encryption schemes in real-time with some performance implications. Fhenix uses mathematics, or fully homomorphic encryption, to protect data in a complex encryption scheme that is resistant to quantum attacks. The technology for FHE is not ready for use today, but its timeline is much shorter than the timeline for quantum computers. This allows the future of blockchains to be built natively with quantum resistance built in, long before quantum computing is ready to attack blockchains.

How much time does the blockchain sector have before the threat of quantum computing becomes inevitable?

Within the next 10 to 20 years, the (blockchain) industry should be fully prepared. Many experts believe that within that time frame, quantum computers capable of cracking current cryptographic systems could emerge. Beyond that, if the problem is not addressed, quantum computers will likely be able to crack most of the current cryptographic systems used in blockchains. The day when quantum computing threatens bitcoin and ethereum encryption is an uncertain future. As for when a computer with enough hardware and software to handle complex problems will be ready, based on modeling the number of qubits developed since 2014 and projecting that timeline into the future1, early estimates are 2035, with some saying much later, as late as 2050.