A paper published recently in the Nature magazine suggests that blockchain could become obsolete by quantum computing. The scientists argue that quantum computers can break the cryptographic codes of a blockchain within a decade. By 2025, up to 10 percent of the global gross domestic product will probably be stored in blockchains.
Quantum computing is a threat to technology blockchain because it increases the fundamental security assumption of elliptical curve cryptography, namely that computers cannot effectively factor large numbers. Quantum computing in practice poses only a minor threat. In practice, Cryptography with a public key is a standard encryption and authentication technique. This technique is used for Internet connections (HTTPS), blockchains, etc. Its security relies, most of the time, on difficult mathematical problems, such as integer factorization, that a traditional computer cannot easily break.
With the peer-to-peer (P2P) network of distributed nodes, the blockchain encryption is secured from most traditional hacking attempts. An attacker can insert a central database and have access to your account numbers and balances in a traditional banking system. If a hacker tries the cryptocurrency block to be modified and the private key redirected, the other nodes on the network will stop the move. Theoretically, such a change could be made by the hacker only if more than 50 percent of blockchain nodes could be modified simultaneously. Computers today do not have the power to perform such a time-limited attack, but quantum computers can pose a new threat. Quantum computing is based on what is referred to as qubits, allowing systems to process values between 0 and 1 and to offer an exponential level of performance.
It’s hard to predict the future. Building a quantum computer is extremely difficult, but the potential to solve major problems that classic computers cannot solve encourages big companies to spend a lot of time and resources first, and progress is quickly made. The greatest danger is that weak defenses against quantum computers are the two asymmetrical cryptographic algorithms (RSA and ECC), which form the basis for all modern encryption in the world. As effective quantum computers become a reality, cryptographic systems are transformed into new encryption algorithms designed against quantum computers. The magnitude of this transition is hard to overemphasize. In the next decade or two, virtually all of the cryptographic software and hardware will have to be reconstructed and replaced. This is a long and complex process, and industry experts will have to work hard to prepare for the major transition.