According to the official Bitcoin Core terminology, «abandoned» («uncoupled» or «stale») blocks (stale blocks) are blocks that are not part of the main chain. They can be created naturally when two miners produce two units almost simultaneously or they may be generated by an attacker to perform an attack on the blockchain. And «blocks orphaned» (orphan blocks) Bitcoin Core refers to those units, the «parent unit» are not yet known, that is, the node it has not yet processed. However, the community often mixes up these concepts, referring to «orphan» the block that was not included in the main circuit, because it was ahead of the other. In particular, this designation uses Blockchain.info.
Returning to the traditional terminology: «parent» connection block-orphans more often than not, are established, the block is confirmed and takes its place in the core network, however, abandoned, «duplicate» blocks are unnecessary and are never displayed in the main Bitcoin chain.
It forms a series of problems, one of them for the miners if the miner randomly generated a block at about the same time with each other and the network chose not his unit, he will not receive awards. In addition, too many such units can make a network more vulnerable to attack, namely the attack of 51% and as a result double spending.
«If the miner-the attacker controls a large share of hashing power, he will always have an advantage in the extraction of the next block and he can choose not to transmit the block immediately to the main chain, but to do it around the same time with the production of [another] new block», — says a leading developer Blockbid Bernard paech, noting that it is necessary to be extremely accurate with the introduction of your unit, always a step ahead of the rival miner. Thus, the attacker creates a parallel, controlled network, and when it becomes long enough, the Bitcoin Protocol begins to consider it a priority. With this power, an attacker can «roll back» transactions, that is, within the «private» chain to accept already verified the transaction void and to re-allocate the funds.
This centralization of hashing can be used not only by hackers but also by all members of the network who want to naibolshey award. The concept of «selfish mining» was first described in 2013 by researchers at Cornell University Emin Kyeong-by Sirer and Eyal Item. They showed that miners can get more together in a group and hiding the newest of the generated blocks, thus the secret of creating your own branch (which at first will technically be a chain of «abandoned units»).
Initially it will be shorter than the main network. However, the «selfish miners» can calculate the time for the «show» of new units, making them public only when the size of the network becomes comparable to the size of the core. Thus, they know that their network (with high probability) will become mainstream, and honest miners, not knowing it, working for nothing. When the «private network» will reach a competitive size and will be presented openly, it can also join and simple miners in search of greater rewards. And this development can also lead to the scenario of the attack 51%, depending on the desires controlling the network pool.
In 2015, the problem of abandoned blocks was discussed in the context of the block size and scalability (in the same year, Bitcoin Core developer Peter Voil proposed SegWit). Rusty Russell, a member of the Blockstream team is currently working to develop our Lightning Network, in the midst of debates 2015 noted that the increase in Bitcoin block size will increase the proportion of abandoned blocks, as the «major blocs need more time to process the Blocks in which no transaction is the smallest, and because they are faster. They still provide a reward of 25 bitcoins [after the next halving the reward of Bitcoin is the bitcoin 12.5. — DeCenter.], although not much help to the users of bitcoin,» wrote Russell. Even then he noted that the growing level of abandoned blocks makes untenable the hypothesis that the miners deliberately refuse centralization not to drop the reputation of bitcoin, followed by its price. «The miners are behaving very badly. Pools organized attacks on each other with amazing regularity… Large mining pools use their power to double spend and steal thousands of bitcoins from the gaming service [Russell refers to the attack, carried out by GHash.IO on BetCoin Dice. — DeCenter.]… If the big miners will be able to use large blocks as a weapon against small [miners], most likely they will be to do it,» warned Russell.
Statistics Blockchain.info the greatest number of abandoned blocks were observed in the period from March 2014 to June 2017 — then in a week I made several of these blocks. However, according to the chart, before this period and after the number of abandoned blocks is equal to zero, which seems implausible. Community members have noted that the chart started to work incorrectly: «They [the cast blocks. — DeCenter.] was significantly less, but still some of it should be,» writes one Reddit user. «This chart is broken, my node got thrown blocks every 500-1000 blocks for the last 6 months,» wrote a user under the nickname statoshi in January, also mentioning that he spoke on this topic with the developer Blockchain.info and «they are aware that it is broken». On another page Blockchain.info reported two cases of abandoned blocks this year: on 12 January and 4 June. The participants noted that there are «several abandoned blocks», which are not reflected in the first chart (and maybe the second too), but also in the community recognize «a sharp reduction» in their numbers. Many assume that this is due to the accelerated allocation of blocks through the relay FIBRE, created by Matt Corallo. The Protocol has not been implemented in the Bitcoin Core client, but can be used by users with full node Bitcoin on their devices. FIBRE «conveys blocks of the network node with little or no delay at light speed through fiber». «For everyone who really wants to understand why (many) technicians so strongly oppose the large size of the blocks and the bitcoin cache, a good start would be understanding the FC — why it exists and how it works,» wrote a Reddit user. He also suggested that the take-off abandoned units was triggered by the growing popularity of bitcoin, whereas prior to 2013 were not enough miners to create a controversial situation with the simultaneously generated blocks.
9 Jun to discussions about abandoned blocks joined by the chief adept of the bitcoin cache Craig Wright, published in his blog post titled «Iron and steel». He argues that such blocks (in the terminology of Wright’s «orphan blocks» — the blocks are orphans) are not a flaw that need to be addressed. Drawing an analogy between forging steel and processing of a bitcoin transaction, Wright compared the abandoned blocks of iron, which is necessary for steel production. «Many developers think that the blocks are orphans are a major problem that needs attention and moreover elimination. Orphans is not a disadvantage, it is carbon which is introduced into the iron and making the steel bitcoin,» writes Wright. He argues that such blocks are a necessary part of the system, while the miners want to get rid of them for obvious reasons — because they do not bring reward. But this is only an individual benefit, whereas more globally, these units do not pose harm or damage the system. «The number of produced units of orphaned does not affect the remuneration structure or the system as a whole,» says Wright, noting that when theoretical reduction in the number of such units or the complete destruction of the awards will not be more. «Miners don’t understand that it [the possibility of thrown blocks. — DeCenter.] is the desired state, and they were accustomed to the fact that it is not desirable, and that if they are removed, then they somehow earn more. This is the lie we must fight,» — said Wright.
He also notes that if you «fix» such blocks, then it can ruin the entire system: «the Simple truth is that the blocks are orphans, and what is understood as related faults, are a key element that provides the Bitcoin. It’s not something that needs to be addressed with the purpose to make Bitcoin more efficient, is a critical aspect, which in the case of its elimination will lead to the collapse of the system.» Wright believes that «Bitcoin requires a certain percentage of inefficiency» and «orphans unite miners» because they oblige them to constantly invest in resources that will help them to stay in the game. «The blocks are orphans contribute to the competition in the Bitcoin like system. Bitcoin is not intended for equal distribution, its goal is to create a competitive environment in which the miners and the businesses are fighting for every advantage, competition is the heart of this system and it cannot work any other way… It helps all miners. However, as always in business, most people think about the short term and sees what they are losing, not the whole system,» writes Wright.
He observes that in game theory the relationship of the miners corresponds to the model of «deer hunting» that describes the conflict between personal and public interests. This type of interaction was described by Jean-Jacques Rousseau in 1755, in his treatise «Discourse on the origin and foundations of inequality among men»: «If hunting deer, everyone realized that he must remain at his post; but if near any of the hunters ran the hare, it is not necessary to doubt that the hunter shamelessly ran after him and overtook the prey, very few will lament that thus deprived of the production of his comrades.» That is what leads to more profit at the same time requires greater cooperation between participants. However, the man — hunter, and miner — easily lends itself to the idea of a small but personal gain in the form of a hare. Thus, according to Wright, if a hunter decides to go for deer alone, «the chance of success is insignificant and suboptimal», but a bigger problem is the need for «too great trust between the players».
The problem Bitcoin solves with asymmetries: as noted by Wright, the incentive system of Bitcoin makes it more profitable to «hunt deer», not the pursuit of small prey. Mining strategy involves a choice between increase hash rate yet (processing power) and increased «connectivity» (i.e. the ease of entry of new players into the system, which increases decentralization). In this case, the first option is more selfish and financially profitable — is the «pursuit of a hare», while the formation of a decentralized network (albeit with smaller individual yields) — collective «hunting deer». In pursuit of hare are a key instrument of ASIC miners, which has declared war on Monero and Ethereum. However, according to Wright, the desired future is a combination of increasing and maximizing can see «connectivity» to the network. He believes that one of the key aspects for the success of the mining system is a «tight connection» between miners and the «system signal»: «Signal will allow players to join together to create a more optimal strategy. A more secure system (more tightly bound) in the interests of both the user and the miner. Orphans mean significant losses for the individual miner… miner that has more than a strong bond with the other participants, can expect a lower proportion of orphans and a higher share of successfully extracted blocks».
Wright stressed that «mining is not about mining blocks, and about to transmit the extracted block to other miners», because the unit is included in the main circuit, only when the other miner «connects» to the next block, and so on.
Additionally, Wright asserts that Bitcoin Cash is the only «true bitcoin», reflecting the original idea of Satoshi, revisits the Bitcoin white paper, saying that abandoned units are an organic part of the system, providing «the only way that miners can honestly vote»: the miners «vote with the power of the CPU and Express their acceptance of valid blocks that continue the chain and rejecting invalid blocks by refusing to build on top of them new blocks. Any needed rules and incentives can be implemented through this mechanism of consensus,» he quoted Wright Bitcoin white paper.