A new research report from Citi warns that the rapid progress in quantum computing could pose a serious threat to the cryptocurrency market, with Bitcoin facing greater risks than Ethereum. The study highlights that breakthroughs in quantum technology could allow practical quantum attacks to become feasible as early as 2030 to 2032, significantly reducing the window for blockchain-based networks to prepare defensive measures.
Bitcoin’s vulnerability to quantum attacks
In Bitcoin transactions, the sender’s public key is exposed on the network until the transaction is confirmed. During this brief window, a quantum adversary theoretically has the opportunity to decipher the corresponding private key, especially as advancements in quantum hardware reduce attack times.
A Google-led study estimates that a quantum computer equipped with 500,000 qubits could breach Bitcoin’s cryptography in a matter of minutes. While such devices do not exist yet, the pace of technological growth is accelerating. Google marks this critical “Q-Day” at 2032, while some academics believe it could arrive as soon as 2030.
One of Bitcoin’s major weaknesses lies in dormant wallets: approximately 6.7 to 7 million BTC are held in addresses whose public keys are already public, making them attractive targets for potential quantum attacks.
This group includes roughly 1 million BTC believed to belong to Satoshi Nakamoto, Bitcoin’s creator, which have remained untouched since the early days. At current market prices, these coins are valued close to $82 billion, underscoring the scale of the exposure.
Governance differences between Bitcoin and Ethereum
According to Citi analysts, Ethereum and other proof-of-stake blockchains can implement protocol upgrades more flexibly thanks to their dynamic governance structures. This gives Ethereum an edge in rapidly adapting to quantum-era threats through updatable network protocols.
Conversely, Bitcoin’s more traditional, collective decision-making approach, while underpinning trust in the project, can slow down urgent updates. Achieving quantum-resistant upgrades for Bitcoin is likely to demand widespread consensus or even a hard fork, posing significant hurdles to quick adaptation.
Citi’s report underscores the need to track proposed Bitcoin improvements such as BIP-360 and BIP-361, emphasizing that even Ethereum is not fully immune to quantum attacks.
Specifically for Ethereum, a quantum-capable attacker could, in theory, seize up to 33% of all staked assets, potentially disrupting block validation and network operations. However, experts note that Ethereum’s adaptability enables it to roll out protective updates more easily.
Preparing for the quantum threat and emerging solutions
The sector is actively researching new cryptographic methods to counter quantum threats. Fireblocks CEO Michael Shaulov, speaking at the Financial Times Digital Asset Summit, described Bitcoin’s quantum vulnerability as more a matter of community coordination than a purely technical issue.
As Shaulov explained, the real challenge lies in readiness: “The entire internet fundamentally needs to make a leap to post-quantum cryptography; broadly, we already have workable algorithms.”
Experts stress that strengthening community coordination and upgrading technical infrastructure will be vital for a smooth transition. As quantum computing power continues to rise, the risk of a critical inflection point for the security of crypto asset networks only grows.
