Crypto Industry Prepares for Quantum Threat as Cost of Defenses Drops
The threat of quantum computers cracking Bitcoin has been a recurring concern in the crypto community. While such a machine does not yet exist, researchers are working on fixes to prevent this hypothetical scenario. The problem lies in Bitcoin's use of elliptic-curve cryptography, which links a private key to a public one. A powerful enough quantum computer could theoretically derive a private key from an exposed public key and drain the wallet.
The industry refers to the arrival of such a machine as 'Q-Day.' While no one knows when or if it will happen, estimates range widely and timelines are compressing, prompting preparation efforts. Three approaches are being explored: making quantum-resistant transactions work under Bitcoin's current rules, changing the protocol itself to adopt post-quantum signatures, and defense at the custody layer.
StarkWare has made progress in reducing the cost of building quantum-safe transactions on mainnet from around $320 to roughly $67 in a single week. However, this is only a workaround, as the transactions are non-standard and do not protect coins whose public key has already been exposed. A soft fork is still considered the better long-term solution.
Coinbase's head of cryptography has outlined plans for post-quantum custody that can adapt to whatever signature scheme Bitcoin eventually adopts. This includes a hardware fallback in case the chosen standard proves incompatible with key-splitting techniques used today.