Citi: Quantum Computing Breakthroughs Accelerating, Bitcoin Faces "Supercritical Quantum Risk"

May 18 – Citibank stated in a newly released research report that quantum computing technology is advancing faster than the market anticipated, amplifying potential security risks to cryptocurrencies and global internet infrastructure, with Bitcoin designated as one of the assets facing the "highest exposure" to these threats. The report points out that the ECDSA elliptic curve encryption system currently used by Bitcoin could theoretically be compromised by a sufficiently powerful quantum computer. In the future, attackers will be able to derive private keys from publicly known public keys, allowing them to forge transactions and steal user assets. Citigroup analyst Alex Saunders noted that due to Bitcoin’s conservative governance structure and slow pace of protocol upgrades, it is far more difficult for the network to quickly roll out quantum-resistant improvements compared to proof-of-stake (PoS) blockchains like Ethereum. The report estimates that approximately 6.5 million to 6.9 million Bitcoin are currently at quantum risk due to exposed public keys, accounting for about one-third of the total circulating supply, with a value of roughly $450 billion at current market prices. This vulnerable pool includes early P2PK addresses, as well as wallets widely believed to belong to Bitcoin’s mysterious creator, Satoshi Nakamoto. Citibank also warns of the "Harvest Now, Decrypt Later" risk, where malicious actors are currently collecting encrypted data and will decrypt it all collectively once quantum computing power matures in the future. However, Citibank remains optimistic about the industry’s long-term ability to adapt to quantum threats, arguing that blockchains can still migrate to post-quantum cryptography and reconfigure their protocols to stay secure. The report highlights two key Bitcoin community proposals worth monitoring: BIP-360 and BIP-361.