How Quantum Computing Could Affect Bitcoin and Blockchain. Shor’s algorithm enables quantum computers to drastically reduce “the time required to factorize the product of two primes.” The algorithm, when executed with a quantum computer, derives a private key from a public key in a predicted few minutes vice the ‘millions of years’ with classical systems. Bitcoins have exposed public keys vulnerable to attack. The exact threat quantum computers will have on digital currency platforms and other types of software applications is debatable. There are some crypto platforms such as Quantum Resistant Ledger working on blockchain projects which are likely to be quantum-resistant.