Good morning Michael, > That’s a fair point about patents. However, note that we were careful about > this. oPoW only uses SHA3 (can be replaced with SHA256 in principle as well) > and low precision linear matrix multiplication. A whole industry is trying to > accelerate 8-bit linear matrix mults for AI so there is already a massive > incentive (and has been for decades). > > See companies like Mythic, Groq, Tesla (FSD computer), google TPU and so on > for electronic versions of this. Several of the optical ones are mentioned in > the BIP (e.g. Lightmatter)
Please note that ASICBOOST for SHA256d is based on a layer-crossing violation: SHA256 processes in blocks, and the Bitcoin block header is slightly larger than one SHA256 block. Adding more to a direct SHA3 (which, as a "sponge" construction, avoids blocks, but other layer-crossing violations may still exist) still risks layer violations that might introduce hidden optimizations. Or more succinctly; * Just because the components have (with high probability) no more possible optimizations, does not mean that the construction *as a whole* has no hidden optimizations. Thus, even if linear matrix multiplication and SHA3 have no hidden optimizations, their combination, together with the Bitcoin block header format, *may* have hidden optimizations. And there are no *current* incentives to find such optimizations until Bitcoin moves to this, at which point we are already committed and it would be highly infeasible to revert to SHA256d --- i.e. too late. This is why changes to PoW are highly discouraged. Remember, ASICBOOST was *not* an optimization of SHA256 *or* SHA256d, it was an optimizations of SHA256d-on-a-Bitcoin-block-header. ASICBOOST cannot speed up general SHA256 or even general SHA256d, it only applies specifically to SHA256d-on-a-Bitcoin-block-header. Regards, ZmnSCPxj _______________________________________________ bitcoin-dev mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
