Mining Diversity & Proof of Work

Question

Dear MultiChain Team

According to your white paper, mining diversity ensures that there is a round robin mining. To my understanding it means that, if set to 1.0 we have a fixed order who is next in line to validate a block. 

My question is if once you are next to validate a block, do you have to do proof of work to amend a block to the chain? 

The reason I am asking is that according to the parameters, you have to show pow by default (see below). Furthermore, in the white paper it says the first version of MultiChain still uses a bitcoin­style proof of work to regulate and randomize each node’s rate of block production. Hence I would assume proof of work has to be done. At the same time, the target-adjust-freq is by default a negative number which deactivates proof of work.

Is multichain therefore using a hybrid solution where you have a fixed order of miners (if mining diversity = 1) but the miners that are in charge for the validation for the next block still have to do proof of work?

 

Parameter	Description	Default
skip-pow-check	Skip checking whether block hashes demonstrate sufficient proof-of-work.	false
target-adjust-freq	Frequency of recalculating proof-of-work difficulty level, measured in seconds. For blockchains which don’t require proof-of-work, use a negative value to prevent recalculation.	-1

Answer 1

Thanks – the white paper is indeed a little out of date on this question.

In the default setup, miners don't use proof-of-work to regulate the rate of block production. They regulate the rate using deliberate delays (with some randomness). With the default parameters, proof-of-work is now only used in the most symbolic way, to ensure that block hashes begin with two hexadecimal zeroes. On average, this means trying 128 different nonces to get a suitable hash, which has trivial computational cost. We did this purely to help developers distinguish visually between block and transaction hashes and it serves no security purpose.