Quantum attacks on Bitcoin, and how to protect against them

See this recent survey article: https://arxiv.org/abs/1710.10377 Briefly, a fully fault-tolerant quantum computer could give a square-root speedup for Bitcoin's proof-of-work, and could completely break its elliptic-curve-based signature scheme. Both issues could in principle be fixed by migrating Bitcoin to quantumly harder problems, though in practice doing so could open up security holes of its own. This hasn't been done, but I think maybe there are other cryptocurrencies trying to use quantum-secure crypto from the outset? Googling just now, I found something called "Quantum Resistant Ledger" (https://theqrl.org/) -- does anyone here know more about what's out there? Let me stress that none of this is a concern with the QCs of the near future, which will have at most a few hundred decent qubits and no error correction, and which will not be able to threaten Bitcoin or any other cryptography.

Considering the original paper's[1] name "Quantum attacks on Bitcoin, and how to protect against them" I wouldn't call this clickbait. [1]: https://arxiv.org/abs/1710.10377

This paper lists a few of the practical concerns for quantum-resistant algos (and proposes an algo that wasn't submitted to NIST Post-Quantum Cryptography Round 1): "Quantum attacks on Bitcoin, and how to protect against them" https://arxiv.org/abs/1710.10377 (~2027?) A few Quantum Computing and Quantum Algorithm resources: https://news.ycombinator.com/item?id=16052193 Responsive HTML (arxiv-vanity/engrafo, PLoS,) or Markdown in a Jupyter notebook (stored in a Git repo with a tag and maybe a DOI from figshare or Zenodo) really would be far more useful than comparing LaTeX equations rendered into PDFs.

There will be around 18M bitcoins in 2020. [1][2] [1] https://en.bitcoin.it/wiki/Controlled_supply [2] https://bashco.github.io/ This paper [3] suggests we'll be needing to upgrade to quantum-secure hash functions instead of ECDSA before 2027. [3] "Quantum attacks on Bitcoin, and how to protect against them" https://arxiv.org/abs/1710.10377 Hopefully, Ethereum will have figured out a Proof of Stake [4] solution for distributed consensus which is as resistant to DDOS as Proof of Work; but with less energy consumption (thereby, unfortunately or fortunately, un-incentivizing clean energy as a primary business goal). [4] https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ