How bitcoin consensus will be achieved?
From a certain perspective, bitcoin block size dispute can be regarded as how to implement the consensus rule bitcoin dispute. These rules should be advocated as the core characters like the Core development team is set for the imaging stone that is difficult to change? Or should be like BitcoinUnlimited put forward that is set to decide according to each node of the operator and generally achieve a consensus emerged that?
Many people love to see bitcoin as an asset, that the property should be immutable and frozen ideas, and they think that the monetary attribute of bitcoin and anti censorship properties are never weakened. But this is not true. The parameters of a software consensus set to “like a stone” is a fantasy.
Because it is impossible to force others to run a specific version of the software, can prevent them to modify the code, the consensus rule is always from the bottom to the way by the network participants selection decision. Understanding these participants choose incentive factors, and the interaction between the choice of these individual node operators eventually emerged common characteristics, contribute to our understanding of the future is how the evolution of the consensus rule. Perhaps this understanding can help us make bitcoin attributes rooted in the market than the set of stone more favorable confidence immutable and frozen.
Why do the consensus rule node
At present, the bitcoin network is followed by implantation of the BitcoinCore client code provisions consensus rule, but this is only a stable form. A node chooses this rule only because all the other nodes in this network are forced to comply with the rules. A miner will not want to waste POW computation to produce a solitary block, because this will cause them to lose the reward block. A businessman will not want to see him for the sale of commodity trading by miners refused to pack, and cause the deal to double. In these examples, we can observe the node operators to accept or reject the block is effective to do follow the purpose of the rule of network consensus.
But in the soft below the bifurcation of what will happen? In a soft bifurcation process, the miners were guided to increase the effective block of the new rules, but before the bifurcation is not mandatory. In this case, the new block rule miner is to change the attribute selection and execution of bitcoin, such as adding a new script to pay such as characteristics of hash.
Another example is the current in the bitcoin network node of BitcoinUnlimited operators, some of them will ignore the effective block size in the current setting. These nodes are connected to each other and still can effectively maintain the Core node, but if the miners can produce one of the longest chain of more than 1MB blocks, they will follow the chain, but the Core node will refuse the chain. In this case, the reason does not enforce the validity rules of 1MB block they are trying to bitcoin as a whole system, and the properties of the whole system are affected. They want a bigger block.
So we can see that the implementation of effective motivation node rules can be divided into two categories:
1. node execution block rule, and to maintain consensus of other nodes on the network.
2. node execution block rule, bitcoin as a system, and try to influence its properties.
If the network in people agree on all the attributes of this system, the two is exactly the same motivation.
In deciding which block effective rules should be implanted into the node is very simple: we simply pointed out the validity rules which blocks can guide the bitcoin system become a global asset, and let all the nodes implement these rules.
It is possible, however, these two goals may be inconsistent. If you think that the Internet should follow certain rules, but the rest of the network and don’t agree? If there is a part of very firmly believe that certain properties they want to integrate, and they are willing to go their own way, from the other part of the network independence and network division, whether through a subsystem, or create a block chain branching, or simply from the development of a copycat currency participation.
But if these two goals are more balanced, things will become more interesting and more complex. We need two motives are mixed, and the balance between the two. Thomas Schelin (TomasSchelling) discussed this dynamic change of mixed motives in his book “conflict strategy” in . Xie Lin provides a theoretical framework to understand that both competition and cooperation incentive mechanism.
Between the bitcoin bitcoin network participants how important attributes in the network selection operation that conflict with each other, and have a strong desire to maintain the network consensus, Xie Lin’s analysis is very useful to understand the situation.
When the same interests of both sides, mixed motive strategy can be regarded as a combination of coordination strategies; and when the interests of both sides are not the same, mixed motive bargaining strategy strategy is similar. In order to achieve the coordination strategy includes both views focusing signal and information collection. Includes a commitment to bargaining strategy forced to obey, usually with an acceptable threat of retaliation.
These strategies also have risks and benefits. In order to understand how these strategies dynamically play a role, we need to know how to motivate the participants and participants, risk tolerance, and behavior interaction how to shape individual participants, and how these individual acts of mutual cooperation in large range, the system emerged specific attributes.
The effectiveness of the rules as a shield split
A node is forced to obey the rules of the block is equivalent to the threat, if not do to other nodes and separation, was kicked out of the network. Whether it is to maintain the current accepted rules, or to promote the new rules, the influence of network nodes accepted rules are nodes through threats do not abide by the rules will be isolated to realize, these rules may also form an independent group does not comply with. This threat depends on the effectiveness of the following factors:
1. to the number of nodes was isolated and the representative of the economic significance.
2. isolated threats communicated to other people in the community level.
3. willing to follow division branch willing and commitment.
The 4. newly formed independent groups expected survival ability. This is the main idea of  DanielKrawisz’s article “who controls the bitcoin”. In this case, the possibility of splitting available investors expected to estimate the actual acceptance.
Let us consider a few specific examples:
Example 1: block size rule
Most of the current node on the network to implement a rule, they refused to accept the block size greater than 1MB block. If one of the miners dug more than 1MB blocks, they “know” (i.e., with very high reliability prediction) of the block will be isolated blocks, they will lose the piece reward. Even if most of the miners agreed to set up a more than 1MB including block chain, if all businesses refuse to exchange and the chain, the chain is of no value. By running the software to block the production of large blocks, if the miners, most economies will promise to split from the economy. If that happens, the market will experience turbulence, will decrease the value of bitcoins. Because of this threat credible, so will not produce such a chain of miners. The miners will chase the money, they will follow the will of the majority of the economy.
But let us imagine if this ratio is reversed what will happen. If the most important node in the economy (bitcoin exchange, payment processing etc.) decided to run BU, but does not enforce the 1MB block validity rules, what will happen? In this case, if a small economy weak people decided to continue to carry out the 1MB block size validity rules, it will be very dangerous for them. By doing so, they would refuse a contains more than 1MB block chain, even if most of the miners through such a proof of work production chain, it will harm the bitcoin network effect, thereby reducing its value. However, in this case, the miners must weigh the network effect and the loss of larger block of benefits, they expect bigger block will increase the value of the network. If the expected benefit of large harm than the threat of a breakaway network, then they can choose to form a larger block.
Examples of 2:2100 million bitcoin rule
If the block size limit is determined by the bottom-up market forces, then the more important block validity rules, such as bitcoin bitcoin issuance schedule and 21 million limit? This process will venture it limited supply principle in violation of bitcoin this important asset?
Let us consider a similar situation in the last example. The upper limit of the majority of the nodes to stop the implementation of bitcoin, perhaps they believe they need more to keep the price inflation (bitcoin measure) not slowing rapidly, or that the miners needed extra pay to pay the cost of network protection. But a few nodes do not agree. Many long-term holders and faithful believers have vowed to refuse a violation of previous monetary inflation schedule blocks, even if it is the longest chain. Now the miners must assess if they dug “bitcoin inflation”, a “common bitcoin” will continue and maintain the value of what is possible? How to compare two kinds of bitcoin market value? Whether the risk dug the currency price loss will exceed their increased block value of reward? If these risks are very important to them, then the “ordinary bitcoin” minority will be able to stop them in violation of existing bitcoin issuance schedule, this is a difficult point of departure. In addition, other economic nodes, similar to assess the situation, will also implement the existing bitcoin issuance schedule, to avoid the risk of falling prices and split.
Example 3: isolated witness soft bifurcation
In the soft bifurcation under the condition of network participants not previously enforced coordination to add a new block of validity rules. This process is often guided by the miners, miners who did not comply with the new rules can be isolated blocks. Non mining nodes do not need to choose whether to follow the new rules, but to follow and accept the long chain, so it causes them to follow the following new consensus miners. In fact, nodes do not the effectiveness of the new rules will follow and realize that most nodes receive chain is effective, it is often considered soft bifurcation favorable reasons.
In a sense, the miners can be used to force the soft forked by agreement changes, whether non mining nodes agree. However, we must realize that there is a risk for those who are forced to implement new rules for soft bifurcation. If most people do not choose community new rule will be applied to their test blocks, they just follow the long chain, but will change the door open is likely to be reversed. The new rules may reduce the safety, safety is similar to the SPV wallet.
Changes in controversial circumstances, this will increase the risk of. The execution node of the new soft forked validity rules must be carefully considered if a breach of new rules of the chain, the rest of the risk they will split with the network, and the network will be in the most long chain extension.
This risk is not only a theory. In fact, after the soft BIP66 bifurcation, in July 2015 there was a consensus on failure. Is the implementation of change is non controversial, it is just a tightening signature encoding rules, to ensure that they follow the standard behavior. Is the coordination between the miners problems. Some of the miners say they will be the implementation of the new rules, but in fact is not checked and refused to comply with the new rules of the block. When a violation of the new rules of the blocks, the miners continue to dig, and extend Qu Kuailian in these blocks at the top. This shows that when nodes began to enforce a new validation rule, there is a risk of consensus split. If you choose not to enforce new rules of the large number of groups, then this kind of risk will be more serious.
Soft and hard bifurcation bifurcation
Observe things – aware node enforcement block validity rule is equivalent to the threat does not enforce new rules of the play network — give us a new way to look at the soft and hard branch bifurcation in this way.
Soft bifurcation is started without previous node validity rules extra block effect. This will increase the risk of node and other nodes division consensus occurs, may reduce the security and trust of the effectiveness of the new rule of.
On the other hand, relates to the threat of falling hard bifurcation. The node can be deleted before being forced to accept the rules to accept hard bifurcation. These nodes will follow the longest work proof chain, so most of them and the risk of the economy lost consensus is very low.
It has been determined that any change in the bitcoin currency attribute can be completed through the soft branch, as hard as simple bifurcation by. For example, the soft block can be used to improve the branching 21 million bitcoin limit. In view of hard currency attribute bitcoin bifurcation are not more dangerous than the soft branch, node operators by relaxing the execution of bitcoin non monetary property rules to reduce the risk and the most meaningful long chain is not compatible with the proof of work, so that the hard change block can be split, you can sense.
About a point in the future
A healthy future bitcoin network should consist of multiple competing software project as each network node client. Some of the projects will be dedicated to meet the needs of the business or the miners. Other users may need to provide a compact lightweight client fraud proof to ensure network security.
In addition, each project in addition to competing with each other, they will also compete in the consensus on the expected behavior. Holders and investors will ensure bitcoin scarcity is maintained. Ease of use of merchants and payment processors will protect the transaction. The miners will earn fee income through the proof of work.
The results of this vision will be a bitcoin network, which by consensus failure becomes impossible, conscious consensus changes, improve the overall value of bitcoins will happen smoothly. The bottom-up selection and individual incentive combination will produce a resilient, flexible and credible system.
Bitcoin is committed to providing a market based on money, and be able to resist the destruction of its intention. In order to prove the value of bitcoin commitment, we need to have confidence in the currency attribute to continue in the future. The current situation is, with a monopoly of the software project, focused on the trust of most people, which makes the basic attribute of bitcoin vulnerable to subversion. The basic characteristics of the market through the interactive participants to protect and support the bitcoin, this is the only hope for bitcoin long-term stability in the future.
Bitcoin community need to reach social consensus in changing the agreement before the idea, this is actually a misunderstanding of how the system is managed. No one should be responsible, so no one should be able to determine whether the agreement for a change has reached a full consensus. Anyone can try hard and bifurcation, determined by the market value if there is such a change.
We should not seek top-down control, should not seek refuge by false social security pressure and the design of the single. In order to monetary attributes through market forces to protect bitcoin from powerful threat of confidence, the best way is to embrace the action mechanism of promoting consensus behavior of the free market.