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November 27, 2017, 10:57:39 AM |
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What are peoples thoughts on Bitcoin and external technology like quantum computing affecting the future of things?
''It is known that a sufficiently large quantum computer35 could be very efficient for
handling problems that rely on trial and error to find a solution. The process of finding
a nonce in order to generate a Bitcoin block is a good example of such a problem. As
of today, one must check an average of 268 nonces to find a suitable hash that allows
a new block to be generated. It is known (see e.g. [15]) that a quantum computer
would need Θ(√N) operations to solve a problem that is analogous to the Bitcoin
puzzle stated above. This same problem would need Θ(N) operations on a classical
computer.
Therefore, a quantum computer would be around √268 = 234 ≈ 17 billion times more efficient at mining the Bitcoin blockchain than a classical computer.
Also, it is worth noting that if a blockchain does not increase its difficulty in response to
increased hashing power, there would be an increased rate of orphaned blocks.
For the same reason, a “large weight” attack would also be much more efficient
on a quantum computer. However, capping the weight from above, as suggested
in Section 4, would effectively prevent a quantum computer attack as well.
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