What hash structure is Facebook Diem using?

Some cryptocurrencies use fixed values in some positions in the resulting hash, like a fixed amount of initial zeros. What fixed positions and fixed values are Facebook Diem using?

• Are you speaking about proof-of-work? Jul 5, 2021 at 13:36
• I wan't to know more about how secure it is. The more fixed values the less variation and less security in the algorithm. Jul 5, 2021 at 13:49
• @Ievgeni Yes this is what is commonly called proof-of-work. I am interested in general how proof-of-work limits the hash function. Jul 5, 2021 at 15:05
• Actually the leading zeros are more of a side-effect. Mostly it's just that the hash value must be less than a specific value (like $2^{256}/difficulty$). Of course that results in the first digits beeing zero. (but allows for smoother steps)
– jjj
Jul 11, 2021 at 23:06

As far as I understood, you are speaking about proof-of-work. But contrarily to what your question said :

Some Crypto currencies use fixed values in some positions in the resulting hash.

It corresponds to proof-of-work. The idea is the following, to guarantee that people which valid a transaction are "real", the have to solve a puzzle, which is basically a preimage of $$\{0\}^\lambda\times\{0,1\}^{256-\lambda}$$ for a specific hash function (parametrized by the transaction) (you can look this to have more precision : Complexity of Hash mining/signing)

But not all the cryptocurrency are using proof-of-work. And in particular, as far as I understood it's not the case for DIEM

Citation in the white-paper: "Second, this class of consensus protocols enables high transaction throughput, low latency, and a more energy-efficient approach to consensus than “proof of work” "

Citation in "The Libra Blockchain" paper:

"To do this, we plan to gradually transition to a proof-of-stake":

https://diem-developers-components.netlify.app/papers/the-diem-blockchain/2020-05-26.pdf

• The second link does not point to a page anymore. Mar 11, 2022 at 17:15
• @DavidJonsson I didn't find anymore the whitepaper. But I've added another relevant link. Mar 11, 2022 at 19:32