Quantum Computers and Blockchain: A Race Against Time

Cardano's founder, Charles Hoskinson, has shared his thoughts on the looming threat of quantum computers to blockchain technology. He believes the main challenge is not about finding solutions but about timing. Implementing new protocols too soon could have significant costs for blockchain networks. The tools to protect blockchains from quantum attacks already exist, according to Hoskinson. The U. S. National Institute of Standards and Technology released post-quantum standards in 2024. However, the issue lies in the potential inefficiencies of these new protocols. They could be slower and less efficient, reducing the throughput of blockchains. The debate around when quantum computers will become a real threat is ongoing. Estimates vary widely, from a few years to over a decade. Hoskinson suggests focusing on DARPA's Quantum Benchmarking Initiative for a more objective assessment. This initiative aims to determine the feasibility of utility-scale quantum computing by 2033.Most major blockchains, including Bitcoin, Ethereum, and Solana, use elliptic-curve cryptography. This could be vulnerable to Shor's algorithm if powerful quantum computers emerge. Hoskinson mentions two main approaches to address this: hash-based and lattice-based cryptography. Hash-based cryptography is simple and conservative but mainly used for signing data. Lattice-based cryptography, on the other hand, supports more advanced cryptographic tools and is seen as better suited for a post-quantum world. Hoskinson notes that lattice cryptography can leverage existing AI hardware, avoiding the need for specialized ASICs. Hoskinson does not advocate for an immediate switch to one method or another. Instead, he proposes a staged mitigation approach. This could involve creating post-quantum-signed checkpoints of Cardano's ledger history using systems like Mithril and the Midnight sidechain. He acknowledges that there are trade-offs, such as moving from instant finality to probabilistic finality, which would have lasting consequences.