[cryptography] hashes based on lots of concatenated LUT lookups

Zooko Wilcox-OHearn zooko at leastauthority.com
Fri Jul 11 18:39:36 EDT 2014

Dear Eugen:

There have been several experiments in this direction, using
"memory-hard" proofs-of-work. For example, this was the motivation for
Litecoin (https://en.wikipedia.org/wiki/Litecoin) to use scrypt in its
Proof-of-Work. To my knowledge, the state-of-the-art design is John
Tromp's Cuckoo PoW: https://github.com/tromp/cuckoo

In my opinion, this is a promising direction to take. It might still
succumb to centralization-of-mining in the long-term, but maybe not.
There's a possibility it would settle into an economic equilibrium in
which independent/hobbyist/small-time mining is sufficiently
rewarding, but customized, large-scale, vertically-integrated mining
is not rewarding enough to justify its costs.

Among anti-mining-centralization techniques that I've studied, this is
the only one that is easy to implement in the near-term, and doesn't
come with too many complications and risks for near-term deployment.

For the contrarian view, arguing that ASIC-resistance is either
undesirable and/or impossible, see this whitepaper by andytoshi:
http://download.wpsoftware.net/bitcoin/asic-faq.pdf . I disagree with
the conclusions, but it makes some good arguments.

For a survey of state-of-the-art ideas about Proof-of-Stake — ideas
which *aren't* easily implementable and which *do* come with
complexity, uncertainty, and risk — see Vitalik Buterin's latest opus:
https://blog.ethereum.org/2014/07/05/stake/ . That guy is a good
thinker and writer! And he appears to have been reading my mind. As
well as adding in a bunch of ideas that were not in my mind, from such
sources as http://eprint.iacr.org/2014/452.pdf .



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