“One particular area at risk are cryptocurrencies,” the abstract notes. “We investigate the risk of Bitcoin, and other cryptocurrencies, to attacks by quantum computers. We find that the proof-of-work used by Bitcoin is relatively resistant to substantial speedup by quantum computers in the next 10 years,” the paper declares. This, they claim, is “mainly because specialized ASIC miners are extremely fast compared to the estimated clock speed of near-term quantum computers.” The good news turns quickly bad, as “the elliptic curve signature scheme used by Bitcoin is much more at risk, and could be completely broken by a quantum computer as early as 2027, by the most optimistic estimates,” state authors Divesh Aggarwal, Gavin K. Brennen, Troy Lee, Miklos Santha, and Marco Tomamichel (emphasis added).
In twenty-one math-laden, chart-heavy pages, which include detailed notes, Quantum is a bear of a read. Authors begin with a basic background to Bitcoin, roll through a nice summation of the distributed ledger, and then begin to propose a series of questions. What “advantage [would a] quantum computer [have] in performing the hashcash [proof of work], and [could it] unilaterally ‘come from behind’ to manipulate the blockchain?” are among the first questions guiding the rest of the paper.
Bitcoin is math, like factorization. Regular computers find it easy enough to exploit, but difficult to ultimately break. Quantum computers, however, are theoretically able to crack such mathematics, and their ubiquity is not far off.
Transaction blocks are basically mathematical functions taming data sets into a specific length, linking in a back-to-front chain. Miners are rewarded by brute-force solving math problems, essentially finding the next right number.
The Cabal Theory