A Singaporean research team has identified ways in which the Bitcoin network could be vulnerable to quantum computer attacks in the not-so-distant future, publishing their findings in a paper aptly titled, “Quantum attacks against Bitcoin and how to protect against them.”
The researchers were interested in how a “sufficiently large quantum computer” could give cryptocurrencies—a “particular area at risk”—fits:
“We find that the proof-of-work used by Bitcoin is relatively resistant to substantial speedup by quantum computers in the next 10 years, mainly because specialized ASIC miners are extremely fast compared to the estimated clock speed of near-term quantum computers.”
“On the other hand, 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.”
The threat, then, is that quantum computers’ incredible brute-force computing power could be used to gain +51% dominance over the Bitcoin network’s computational power—a hijacking, as it were.
A crucial feature of Bitcoin is its security, but there is a problem on the horizon, thanks to quantum computers. https://t.co/H5XCQrW3qT
— MIT Tech Review (@techreview) November 10, 2017
For example, consider the graph below. In blue, you’ll see the Bitcoin network’s Hash-per-Second (HpS). In red, the hash power of a single theoretical quantum computer.
There is hope, though
The researchers’ counterargument against megacomputers vs. Bitcoin boils down to incentivization—an age-old concept implemented to ingenious effect by Satoshi Nakamoto.
In other words, Proof-of-Work (PoW) miners are incentivized to secure the network. They’re not incentivized to sit back and do nothing while their prospective earnings are threatened. They’re highly economically motivated to use increasingly specialized mining rigs, if not quantum computers themselves, to defend the network from attack.
Altneratively, the researchers pointed to other PoW systems like Daniel Larimer’s innovative Momentum as “resistant to speedup by a quantum computer[s],” making them potentially attractive protocols in the future.
TLDR: Researchers in Singapore have concluded that quantum computers might be advanced enough by 2027 to start overpower Bitcoin’s network.