Bitcoin mining is now almost exclusively performed by Bitcoin-specific ASICs (application-specific integrated circuits). These chips are made by a few startup manufacturers and cannot be used for anything else besides mining Bitcoin or closely related cryptocurrencies . Because they are somewhere between a thousand and a million times more efficient at mining Bitcoin than a general-purpose computer that you can buy for the same price, they have quickly become the only game in town.
Many have lamented the rise of ASICs, feeling it departs from the democratic “one computer, one vote” vision laid out by Satoshi Nakamoto in the original Bitcoin design. There is also significant concern that mining is now too centralized, driven by ASICs as well as the rise of mining pools. Because of this, there have been many efforts to design “ASIC-resistant” mining puzzles. One of the earliest alternatives to Bitcoin, Litecoin, chose the memory-hard scrypt instead of SHA-256 in the hope of preventing ASIC mining. Despite this, there are now ASICs for mining Litecoin and their speedup over general-purpose computers may be even greater than that of Bitcoin ASICs. Litecoin’s developers themselves have essentially given up on the principle of ASIC-resistance. Subsequent efforts have included X11, which combines eleven hash functions to attempt to make ASICs difficult to build, but it’s probably only a matter of time before X11 ASICs arise as well. It’s been convincingly argued that ASIC-resistance is probably impossible in the long-term, so we should all accept that ASICs are inevitable in a successful cryptocurrency.
I would like to expand on the argument here though by positing that ASICs may actually make Bitcoin (and similar cryptocurrencies) more stable by ensuring that miners have a large sunk cost and depend on future mining revenues to recoup it. Even if it were technically possible to design a perfectly ASIC-resistant mining puzzle which ensured that mining was efficient on general-purpose computers, this might be a bad idea if it meant you could obtain a lot of computational capacity and use it in a destructive attack on Bitcoin without significantly devaluing your computational resources’ value. [Read more…]