[BMR] Merged mining in BitMonero (proposal)

[thankful_for_today]

Hello!

BitMonero is a new CryptoNote-based currency we have started a week ago. In this post I'll explain what is a merged mining and why I consider it as a good feature.

Merged mining is the way to use hashpower from one blockchain in several other blockchain. MM happens between two blockchains:

- a "donor" blockchain knows nothing about MM
- a "merge mining" blockchain is able to accept PoW from "donor" blockchain. Several "merge mining" blockchain can use work from "donor" blockchain at the same time (on same mining machine).

Main facts about merged mining

1. From the network's point of view MM saves energy because we use same work for several blockchains.

2. From miner's point of view MM gives additional coins to miners.

3. MM increase hashpower of all chains involved because some miners will switch from one-chain mining to MM.

Merged mining algorithm

Let's suppose we have a "donor" blockchain AAA and two "merged mining" blockchains XXX and ZZZ. As it is stated above AAA doesn't know anything about merged mining. XXX and ZZZ have to support it explicitely. Non-merged miner will mine each chain separately. Merged miners will do following actions:

1. Create block templates for XXX and ZZZ: blkXXX and blkZZZ
2. Create block template for AAA that includes references to blkXXX and blkZZZ. References are stored in coinbases because there is no suitable location in block header.
3. Mine block blkAAA:
3.1 Calculate hash for blkAAA (we don't need to calculate hash directly for "merged mining" chains as soon as they can accept PoW from "donor")
3.2 Compare hash with difficulty for AAA, XXX and ZZZ.
3.3 Submit block to corresponding network if difficulty is sufficient
3.4 Go to 3.1

Miners are free to choose any "donor" blockchain and any set of "merged mining" chains they want to support. A number of mining configurations is possible:

1. One chain mining

2. One "donor" + one "merged mining"

3. One "donor" + several "merged mining"

4. Fake "donor" + several "merged mining"

The number of "merged mining" chains miner can support at the same time isn't limited directly. As soon as at least one difficilty target is met miner can send a block to corresponing network. But there is always only one "donor" chain at the same time: each miner has to choose his own "donor" chain or use fake "donor" for mining. Fake donor means that you really don't mine any "donor" chain but only mine several "merged mining" chains together. Configuration with two donor chains isn't possible.

"Donor" chain can have more or less hashpower than "merged mining". Relative hashrate isn't important for merged mining: "donor" chain can have less hashrate that "merged mining" one. "Merged mining" network accumulates hashrate from both "donor" chain and from all other "merged mining" chains with same PoW. "Donor" chain can't use PoW from other networks directly.

Bytecoin and BitMonero merged mining

In out case BCN is a "donor" blockchain. No code changes will be implemented in BCN.

BMR can be a "merged mining" chain. In case it will accept PoW from BCN or from any other "donor" or "merged mining" blockchain with CryptoNight PoW.

In case of merged mining available each miner can choose

- to use or not to use "donor" chain
- the specfific "donor" chain to use
- the number or "merged mining" chains to support

This way nobody will loose from merged mining with such an implementation.

Action plan

Merged mining needs a hardfork: all users are to update their damons. We can't do such changes ourselves. We are asking miners to state their opinions. How to express your opinion:

- if you don't want "merged mining" in BitMonero you don't have to do anything
- if you want "merged mining" in Bitmonero you have to update yout mining daemon now. New mining daemon will issue blocks with an incremented minor_version field. In case > 75% of blocks mined will have an incremented minor_version we will accept "merged minng" and new code will be published on git.

Calculations will be perfromed on 29 April. 750 blocks with incremented minor_version from last 1000 are required to switch for merged mining.

Here is a "voting for merged mining" daemon for Windows:
https://mega.co.nz/#!ogxTXIBJ!GeAuLXWLM-YAF41ylfn2w14ZTUovRehicrevIIAph9Q

For Linux you need to build it yourself.

[the_darkness]

For what it's worth I really don't think Monero needs merged mining and strongly discourage others from following through with this. Monero can stand on its own as the first freely-distributed Cryptonote currency and doesn't need to be tied to Bytecoin, which is more than 80% mined already. Why bother affiliating with another coin when Monero has already seen huge increases in hash in only one week of mining? If a botnet hadn't jumped on Bytecoin Monero was already on track to surpass its net hash.

[BitRock]

For what it's worth I really don't think Monero needs merged mining and strongly discourage others from following through with this. Monero can stand on its own as the first freely-distributed Cryptonote currency and doesn't need to be tied to Bytecoin, which is more than 80% mined already. Why bother affiliating with another coin when Monero has already seen huge increases in hash in only one week of mining? If a botnet hadn't jumped on Bytecoin Monero was already on track to surpass its net hash.

+1

[smooth]

- if you want "merged mining" in Bitmonero you have to update yout mining daemon now. New mining daemon will issue blocks with an incremented minor_version field. In case > 75% of blocks mined will have an incremented minor_version we will accept "merged minng" and new code will be published on git.

Please make sure that the "updated" version requires the miner to actually take some action to vote (such as a config option). Having people who simply download and use the latest version automatically and invisibly vote in favor by default makes this concept of voting into a sham.

As I have said on other threads, the idea that you can merge mine or not at your choice and no one loses from having merge mining implemented if they don't want to do it is false. The difficulties will adjust so that those who don't merge mine will get less and everyone is forced to mine both chains to compete.

It is also a myth that it reduces energy usage. People mining one or the other will just mine both, energy usage remains the same. It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

I'm very disappointed that TFT is using false arguments like energy savings or more coins to advance this agenda.

[GreekBitcoin]

I also dont want merge mining with bytecoin. I think its better for monero to stay away from 80% premined bytecoin.

[tifozi]

I also dont want merge mining with bytecoin. I think its better for monero to stay away from 80% premined bytecoin.

Ditto

[thankful_for_today]

- if you want "merged mining" in Bitmonero you have to update yout mining daemon now. New mining daemon will issue blocks with an incremented minor_version field. In case > 75% of blocks mined will have an incremented minor_version we will accept "merged minng" and new code will be published on git.

Please make sure that the "updated" version requires the miner to actually take some action to vote (such as a config option). Having people who simply download and use the latest version automatically and invisibly vote in favor by default makes this concept of voting into a sham.

Ok. That's right. I will fix this before making any calculations.

[smooth]

- if you want "merged mining" in Bitmonero you have to update yout mining daemon now. New mining daemon will issue blocks with an incremented minor_version field. In case > 75% of blocks mined will have an incremented minor_version we will accept "merged minng" and new code will be published on git.

Please make sure that the "updated" version requires the miner to actually take some action to vote (such as a config option). Having people who simply download and use the latest version automatically and invisibly vote in favor by default makes this concept of voting into a sham.

Ok. That's right. I will fix this before making any calculations.

Thank you.

[Rias]

- if you want "merged mining" in Bitmonero you have to update yout mining daemon now. New mining daemon will issue blocks with an incremented minor_version field. In case > 75% of blocks mined will have an incremented minor_version we will accept "merged minng" and new code will be published on git.

As I have said on other threads, the idea that you can merge mine or not at your choice and no one loses from having merge mining implemented if they don't want to do it is false. The difficulties will adjust so that those who don't merge mine will get less and everyone is forced to mine both chains to compete.

It is also a myth that it reduces energy usage. People mining one or the other will just mine both, energy usage remains the same. It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

I'm very disappointed that TFT is using false arguments like energy savings or more coins to advance this agenda.

As far as I got TFT, he got valid points.

It does save your energy and let's efficiently mine two coins with no extra effort. Given the current exchange rate of BCN, I think it might still be a good idea to get twice the income with the same effort.

At least, it's from my perspective, I might be wrong.

The actual life and miners' behavior is not rigid math, so we can't actually prove the theoretical proposition about merged mining unless we give it shot. My point is, I'd better mine two coins instead of one. Where am I wrong exactly?

[Cheesus]

Well, it’s not exactly “twice the income” but it’s still an income.

It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

But you will gain the reward from both chains, aren’t you?  I don’t understand it fully but from my side mining 2 chains is better than mining 1. Even if the difficulty is going up.

So, currently I support MM implementation.

[smooth]

Well, it’s not exactly “twice the income” but it’s still an income.

It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

But you will gain the reward from both chains, aren’t you?  I don’t understand it fully but from my side mining 2 chains is better than mining 1. Even if the difficulty is going up.

Not its exactly the same, since each chain has a fixed reward schedule. No more coins are being given out. Let's say hypothetically (because it makes the calculation simpler but does not change the result) that half the people are mining bytecoin and half are mining monero. So half are getting the bytecoins and half are getting the monero coins.

After merged mining, assuming both coins retain significant value, everyone will mine both, the difficulty of each will double, and everyone will get half the coins on the chain they were mining before, plus half of the other coins form the other chain.

There are no free coins here. Where would they come from, since the reward output in both chains is fixed?

[smooth]

Where am I wrong exactly?

You're ignoring that the difficulty of both coins will go up because nearly everyone will be mining both instead of choosing between one or the other. Yes, you will get two coins, but you will get half as many of each.

Likewise, if you mine anything at all with your computer or computers, the energy usage is the same. It doesn't matter if you mine one coin at lower difficulty or two coins at higher difficulty. Same energy usage, same output.

[Cheesus]

Well, it’s not exactly “twice the income” but it’s still an income.

It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

But you will gain the reward from both chains, aren’t you?  I don’t understand it fully but from my side mining 2 chains is better than mining 1. Even if the difficulty is going up.

Not its exactly the same, since each chain has a fixed reward schedule. No more coins are being given out. Let's say hypothetically (because it makes the calculation simpler but does not change the result) that half the people are mining bytecoin and half are mining monero. So half are getting the bytecoins and half are getting the monero coins.

After merged mining, assuming both coins retain significant value, everyone will mine both, the difficulty of each will double, and everyone will get half the coins on the chain they were mining before, plus half of the other coins form the other chain.

There are no free coins here. Where would they come from, since the reward output in both chains is fixed?

But the block you found is going to the both chains. That’s the main cause of merged mining to me.

Also, difficulty won't go up this drastically - you're assuming that with double difficulty the reward will be cut in half but it won't.
According to the bytecoin.org:
Block reward decreases each block according to the formula:
BaseReward = (MSupply - A)/218
where MSupply = (264 - 1) atomic units and 'A' is amount of already generated coins;

Reward will decrease, yes, but not that hard. I'm not that good at math but I think slightly lower reward from both coins simultaneously is better then current reward from 1.

[smooth]

Well, it’s not exactly “twice the income” but it’s still an income.

It also does not give additional coins. Again more miners on both chains means the difficulty goes up. Coins awarded remains the same.

But you will gain the reward from both chains, aren’t you?  I don’t understand it fully but from my side mining 2 chains is better than mining 1. Even if the difficulty is going up.

Not its exactly the same, since each chain has a fixed reward schedule. No more coins are being given out. Let's say hypothetically (because it makes the calculation simpler but does not change the result) that half the people are mining bytecoin and half are mining monero. So half are getting the bytecoins and half are getting the monero coins.

After merged mining, assuming both coins retain significant value, everyone will mine both, the difficulty of each will double, and everyone will get half the coins on the chain they were mining before, plus half of the other coins form the other chain.

There are no free coins here. Where would they come from, since the reward output in both chains is fixed?

But the block you found is going to the both chains. That’s the main cause of merged mining to me.

Exactly, but you will find fewer blocks (higher difficulty).

Also, difficulty won't go up this drastically - you're assuming that with double difficulty the reward will be cut in half but it won't.

I was only assuming double because that makes the calculation and illustration easier. If you work it out with actual hash rate numbers you get the same result -- some coins on each chain, but fewer of each.

You can already get some coins on each chain if you want, just mine with one computer on each chain, or if you only have one computer, switch off between them.

There is no free lunch. If you can mine both, so can everybody else, and the difficulty must go up.

[EndlessWin]

the same situation was with the namecoin, isn't it? what was the outcome ?

[smooth]

the same situation was with the namecoin, isn't it? what was the outcome ?

The outcome was that the namecoin difficulty shot up my an enormous amount. Namecoin was easily solo mineable before merged mining went in. I know this because I mined namecoin before the merge. After the merger, it was not.

I tried to find a chart showing namecoin difficulty from way back then (2011), but I couldn't. Bitcoin difficulty probably also increased a little on the margin, since people previously mining namecoin instead of bitcoin switched over to mining both, although namecoin was so much smaller than bitcoin this effect was likely negligible.

[mickey_miner]

What do I do to vote?  Linux

[smooth]

What do I do to vote?  Linux

If you want to vote against, do nothing and do not upgrade your nodes.

If you want to vote for, you can perhaps just upgrade to the current version from github, although TFT said he would be changing it to require some explicit action to vote, instead of treating everyone who newly downloads or upgrades as voting "for" by default.

[mickey_miner]

What do I do to vote?  Linux

If you want to vote against, do nothing and do not upgrade your nodes.

If you want to vote for, you can perhaps just upgrade to the current version from github, although TFT said he would be changing it to require some explicit action to vote, instead of treating everyone who newly downloads or upgrades as voting "for" by default.

OK thanks.  Then I do nothing.  Where is updated code for linux compile?  I don't see.

[smooth]

What do I do to vote?  Linux

If you want to vote against, do nothing and do not upgrade your nodes.

If you want to vote for, you can perhaps just upgrade to the current version from github, although TFT said he would be changing it to require some explicit action to vote, instead of treating everyone who newly downloads or upgrades as voting "for" by default.

OK thanks.  Then I do nothing.  Where is updated code for linux compile?  I don't see.

Precompiled? I'm not sure. I always build my own.