Bitcoin Q&A: Migrating to Post-Quantum Cryptography

Keywords/phrases: Quantum cryptography, quantum cryptoanalysis, quantum computing. Bitcoin uses SHA-256. In cryptography there is a 20-30 year lifecycle for an algorithm before it gets exceeded by new technologies and developments in mathematics. Both the signing and hashing algorithms can be upgraded in Bitcoin if there is a need to do that. Quantum cryptography represents a threat only if unevenly distributed in commercial sectors. If it is available to only one actor, and not all actors, they are unlikely to use it against Bitcoin; instead they're going to keep it secret and use it when they're threatened by ex. cryptographically secure nuclear weapons. Intelligence agencies who have that kind of significant computing advantage don't use it until there is a dire emergency, because once you use it everyone will know you have it. After that all the algorithms get changed, so you better make it good. If it is widely available, all the miners update to quantum computers and we're going to be looking at several orders of magnitude in improvement, because running one is neither free nor easy. We don't know what the economics will be yet, but we will solve problems when it's necessary.