At a recent panel during the Ethereum developer conference, ETH Denver, experts focused on the looming threat of quantum computing to Bitcoin’s security, particularly its digital signatures. Hunter Beast, co-author of BIP 360, highlighted that while Bitcoin’s hashing algorithm, SHA-256, is currently secure against quantum attacks due to the scale of computing power required, the real concern lies in the future viability of its digital signatures.
Beast explained that although breaking SHA-256 could require a quantum computer—envisioned to be larger than the moon—Shor’s algorithm poses a more immediate risk. This algorithm, developed by mathematician Peter Shor, could reverse-engineer the private keys of Bitcoin users through their public keys if a sufficiently powerful quantum computer were to emerge. Alex Pruden, CEO of Project Eleven, emphasized the implications of such an event, noting that successful attacks utilizing Shor’s algorithm could allow hackers to gain ownership of Bitcoin simply by knowing public keys.
Recent advancements in quantum computing, particularly by companies like Google and IBM, have sparked concern regarding these potential risks. Pruden pointed out that Google’s recent developments could indicate a new phase in quantum scalability, leading to fears of a practical quantum computer making digital currencies vulnerable sooner than anticipated. In light of these developments, both Bitcoin and Ethereum developers are actively exploring solutions to this quantum threat.
Estimates regarding the quantum hardware necessary to breach Bitcoin’s signature scheme have shifted dramatically. In 2021, experts estimated that 20 million qubits would be needed, but newer research suggests that this number could be reduced to around 100,000 qubits.
Currently, approximately 30% of Bitcoin exists under exposed public keys, leaving it vulnerable. Data from Project Eleven indicates that over 6.9 million coins are in such a precarious situation, including 1.7 million coins mined in Bitcoin’s early days. The risk of what Beast termed a “long exposure attack” highlights the urgent need for the community to address these vulnerabilities.
Isabel Foxen Duke, another co-author of BIP 360, noted that the problem extends beyond mere technical solutions. She indicated that the challenge of transitioning Bitcoin to quantum-safe addresses is not just a matter of cryptography but includes complex sociopolitical dynamics within the Bitcoin community. For instance, older coins belonging to Bitcoin’s pseudonymous creator, Satoshi Nakamoto, may remain permanent liabilities as their migration to safer standards is fraught with debate.
Foxen Duke warned that if quantum computing capabilities were to advance before the community reaches a consensus on mitigation strategies, the consequences could be dire. She pointed out the potential for billions of dollars worth of Bitcoin to flood the market, leading to a catastrophic devaluation and possibly threatening the infrastructure of Bitcoin itself.
As discussions around the implications of quantum computing on digital currencies continue, both the Ethereum Foundation and Coinbase are taking proactive measures. The Ethereum Foundation has initiated a post-quantum security team, while Coinbase has assembled an advisory board to assess quantum risks. These initiatives represent a growing recognition of the urgency in addressing the intersection of quantum computing and blockchain security.
