Quantum Clock Ticking: Why Bitcoin Faces Greater Risk Than Ethereum

A recent research note from Citi analysts confirms what many in the crypto space have feared: quantum computing poses a significantly greater risk to Bitcoin than to Ethereum. The gap isn't just technological—it's also about governance.

Why Bitcoin is Exposed

Bitcoin's security relies on elliptic curve digital signature algorithms. When a transaction is broadcast, the public key is briefly exposed on-chain. A quantum computer running Shor's algorithm could, in theory, derive the private key in minutes. A Google Quantum AI paper, in collaboration with Stanford and the Ethereum Foundation, estimated that a quantum computer with fewer than 500,000 physical qubits could break Bitcoin's cryptography in about nine minutes—and the computing power needed is 20 times lower than previously thought.

Nic Carter, co-founder of Coin Metrics, has warned that quantum computing is "the biggest long-term risk to bitcoin's core cryptography" and that developers are "sleepwalking towards collapse." He estimates a quantum computer could break elliptic curve cryptography as early as 2028, potentially exposing 6.9 million BTC in legacy wallets and Taproot outputs.

Bitcoin's Governance Problem

Bitcoin's governance is intentionally conservative, making upgrades extremely slow. SegWit took 8.5 years from conception to adoption; Taproot took 7.5 years. The current quantum proposals, BIP-360 and BIP-361, are still in draft or early testnet stages. A full transition to post-quantum signatures would be the most contentious change Bitcoin has ever attempted, and most Bitcoin Core developers have shown limited urgency.

Ethereum Has Already Acted

Ethereum's approach to quantum resistance is a structured roadmap already in execution, built on NIST post-quantum cryptography standards finalized in August 2024. The Pectra upgrade (May 2025) introduced EIP-7702, allowing individual accounts to switch to quantum-safe signatures voluntarily. The upcoming Hegotá hard fork (H2 2026) embeds this further at the protocol level, with milestones targeting completion of core post-quantum infrastructure by approximately 2029.

The Institutional Calculus

For corporate treasurers and sovereign wealth managers, quantum risk is no longer a tail scenario. Governments are already acting: U.S. federal agencies faced an April 2026 deadline for post-quantum transition plans, the EU targets 2030, and the G7 published a coordinated roadmap in January 2026.

The author, Samir Tabar, who sold Bit Digital's Bitcoin holdings and built one of the largest corporate Ethereum treasuries, argues that Ethereum is the more adaptive, capable, and durable asset. He concludes: "Ethereum is the asset whose architecture was built to survive what is coming."