Cryptography Gets Busted
For their paper, Aggarwal and his colleagues examined how quantum computers could break through Bitcoin’s security in two ways: by mining more than classical computers can and by cracking Bitcoin’s cryptographic keys.
If a miner controls more than 50 percent of the computational power on a blockchain network, they can use that majority control for malicious activity. The researchers found that the application-specific integrated circuits (ASICs) currently used by most cryptocurrency miners should be able to maintain a speed advantage over quantum computers for the next 10 years, so miners likely won’t be able to use quantum systems for nefarious purposes in this manner for at least a decade.
As for cracking today’s cryptographic keys, part of Bitcoin’s security protocol involves every bitcoin owner possessing two encryption keys: a private one and a public one. The latter can be easily generated using the former, but the reverse is far more difficult. An owner’s signature is verified without revealing the private key using a technique called elliptic curve signature scheme.
While conventional computers don’t possess the necessary computational power to derive a private key from a public key, quantum computers could do it rather easily. “The elliptic curve signature scheme used by Bitcoin…could be completely broken by a quantum computer as early as 2027,” Aggarwal and his colleagues wrote.