Quantum Computing

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Once purely theoretical, “majority” or “51%” attacks on public blockchains have dealt participants a reality check: The fundamental assumption of Satoshi Nakamoto’s 2008 Bitcoin whitepaper (that computing power will remain sufficiently decentralized in blockchain networks that rely on a “proof-of-work” consensus mechanism) can in practice actually be exploited to enable double spending.

“The system is secure as long as honest nodes collectively control more CPU power than any cooperating group of attacker nodes…. If a majority of CPU power is controlled by honest nodes, the honest chain will grow the fastest and outpace any competing chains. To modify a past block, an attacker would have to redo the proof-of-work of the block and all blocks after it and then catch up with and surpass the work of the honest nodes.” – Satoshi Nakamoto, Bitcoin: A Peer-to-Peer Electronic Cash System

These incidents have provided opportunities for developers of both public and private blockchains, as well as operators of blockchain-based digital asset trading platforms, to learn from the first generation of blockchain deployments.

2018 promises great inroads in the realm of “quantum computing.”  While conventional computers use binary data or bits (i.e., 0s and 1s) to store and process information (a bit can either store a 0 or 1), a quantum computer operates based on the laws of quantum mechanics and uses quantum bits or “qubits,” which can be in a “superposition” state of zero and one at the same time (e.g., a qubit can store a 0, 1, or a summation of both 0 and 1).  Ultimately, it is expected that quantum computers will be able to solve complex computations exponentially faster – as much as 100 million times faster — than classic computers.

While currently not ready for general commercial applications, quantum computers could someday allow scientists and others to solve very complex problems in chemistry, applied mathematics, biology and engineering, and also push huge advances in areas such as artificial intelligence, machine learning, large database searching and big data processing.

How could quantum computing impact blockchains?