I am in the process of designing a cryptographic Proof of Storage (PoS) that relies on single threaded computation of SHA256 hashes. In practice, my algorithm is equivalent to computing for some string S the value SHA256^N(S) = SHA256(SHA256(SHA256(...(SHA256(S)))).

This forces anything computing that function to use only one thread, as each SHA256 step needs the output of the previous as input.

Now, I know that ASIC miners exist that can compute SHA256 hashes at an enormous rate. This, however, is due to their parallelism: completing Proofs of Work (i.e., finding zeros of hash functions) is an embarassingly parallel problem and can be computed very fast on massively parallel devices. This is not what I am looking for.

What I am looking for is the fastest device that would be able to compute my function, i.e., single-threaded computation of a SHA256, then the SHA256 of its output, the SHA256 of the result and so on.

I thought that maybe in this case the best hardware would be the fastest CPU in terms of single threaded performance: I found here that Intel Core i7-7700K could be a good place to start looking for.

Is there any other known specialized hardware device that could carry out the task faster?

  • Have you done any research on your own into such devices? – NZKshatriya Jan 13 '17 at 19:57
  • Apart from a couple of days of Googling, I think I lack the hardware expertise I'd probably need to know where to look! – Matteo Monti Jan 13 '17 at 19:58
  • What's your budget? – 0-60FPS Jan 13 '17 at 21:18
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    If your budget is truly unlimited, get someone to design and fab an ASIC for your specific task. The cost will be in the millions of dollars, but that's not a problem on an unlimited budget. – Mark Jan 14 '17 at 0:48
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    Also note that you can also just take a Bitcoin miner ASIC and divide the hashing rate by N to see how many different such hashes they can do per second. – SEJPM Jan 14 '17 at 10:08

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