2022

Heinonen, Henri T.; Semenov, Alexander

We analyzed the Bitcoin difficulty data and noticed that the difficulty has been around the level of 1013 for three years (H2 2018–H1 2021). Our calculation showed about 1028 hashes have been generated during bitcoin mining around the world for securing the addition of 703,364 blocks to the Bitcoin blockchain. We introduced a concept of Recycling Hashes in the hope to (a) jump-start bespoke silicon (customized silicon) for reversible computing, (b) open up the possibility of Bitcoin’s Proof-of-Work to be less energy-consuming in the future, (c) provide scientific value or new services, in the form of entropy pool or random numbers, to Internet users while still achieving the security level of Bitcoin of today, (d) decrease the old mining hardware e-waste by using them to recycle hashes to the entropy pool, and (e) solve the problem of low mining rewards. We found that the bit rates of the current irreversible bitcoin miners are millions of times as high as the existing Internet connections, so it would be difficult to send all the hashes generated in real-time via the Internet. Even if only 0.000000355% of the hashes can be recycled, it would still mean that 355⋅1018 hashes (355 EH) would have been recycled since the beginning of Bitcoin. Storing all the hashes, so far, would need storage of 2.560⋅1030 bits, and it is not currently possible to keep all of them. Our simulation of 10,000 bitcoin hashes showed that the occurrences of zeros and ones in bitcoin hashes are almost 50% and 50%, so it is an encouraging finding for seeding the Pseudorandom Number Generators. We also proposed a second coin for the Bitcoin blockchain, an inflationary coin with a different currency unit (BTCi), to motivate the entropy providers to keep the old mining hardware online. The proposed second coin might keep Bitcoin’s security model safe in the future when the deflationary bitcoin (BTC or BTCd) block reward is becoming too low.