Quantum computers are posing a serious challenge to the security of the bitcoin blockchain. Presently, about 25% of the bitcoins in circulation are vulnerable to a quantum attack. If you have bitcoins in a vulnerable address and believe that progress in quantum computing is more advanced than publicly known, then you should probably transfer your coins to a new address (don’t forget to make a secure backup of your private key).
In case your own bitcoins are safe in a new address, you might still be impacted if many people will not (or cannot) take the same protection measures. In a situation where a large number of bitcoins is stolen, the price will most likely crash and the confidence in the technology will be lost.
Even if everyone takes the same protection measures, quantum computers might eventually become so fast that they will undermine the bitcoin transaction process. In this case the security of the bitcoin blockchain will be fundamentally broken. The only solution in this case is to transition to a new type of cryptography called ‘post-quantum cryptography’, which is considered to be inherently resistant to quantum attacks. These types of algorithms present other challenges to the usability of blockchains and are being investigated by cryptographers around the world. We anticipate that future research into post-quantum cryptography will eventually bring the necessary change to build robust and future-proof blockchain applications.