Banks are buying Bitcoin vaults, but a quantum problem may be waiting inside
Major banks are moving into crypto custody: BNY will offer Bitcoin and Ethereum custody in Abu Dhabi, and Standard Chartered is acquiring Zodia Custody. Custody has shifted from a crypto-native back-office function to a strategic banking priority. At the same time, Taurus warns that current custody systems are not ready for the eventual quantum transition. Bitcoin and Ethereum rely on elliptic curve signatures that a sufficiently powerful quantum computer could break, though that threat is still likely years away. NIST has already set post-quantum standards and is phasing out current schemes over the next decade. The key issue is blockchain coordination: custodians cannot unilaterally switch to post-quantum signatures because networks must accept them first. Taurus argues HSM-based custody is easier to upgrade, while MPC faces deeper structural challenges because it still depends on classical signature math. The broader risk is that institutions are building large custody stacks before blockchain post-quantum migration is settled.
