Vitalik Buterin: Talking about the public and private block chain block chain
In the past year, the concept of "private block chain" (private blockchains) became a buzzword in the block chain technology discussions.
In essence, compared to the fully open, uncontrolled, and to ensure the network security by encrypting the economic system (for example, as well as the interests of the workload proved pow prove pos), "private block chain" can also create access more stringent control, modify or even read access to only a few users of the system, while this system still retains its authenticity and chain blocks to the center portion of the properties.
Financial institutions have a great interest in such a system, which also led to fierce opposition from some people, they think this development is contrary to the decentralized nature, which is that old-fashioned outdated middlemen desperate behavior ( or simply put forward a non-Bitcoin application error). However, for those who want a better simply because the benefit of mankind, or just continue to seek to provide customers with better services in terms of people, public and private chain block any practical difference?
First of all, what we have on hand, how many choices? Summed up, we have three kinds of database applications category Chain Block:
Public Block Chain (Public blockchains)
Public block chain refers to anyone in the world can read, anyone can send the transaction and the transaction can be effective confirmed, anyone can participate in the block in which the consensus-building process chain - the consensus process to determine which blocks It may be added to the chain block and clear the current status.
As the center of the center of trust or a quasi-substitute for, public safety block chain consisting of "encrypted digital economy" Maintenance - "encrypted digital economy" to take interest in the workload of proof mechanism or mechanisms and other ways to prove the economic incentives and encrypted digital verify that combines, and follow the general principles: reward, proportional contribution from each person to obtain economic and consensus process made. These blocks chains are typically considered to be "fully decentralized" in.
Community Block Chain: (Consortium blockchains)
Community block chain refers to the process by which consensus preselected node control block chain; for example, we might imagine a community of 15 financial institutions, each institution running a node, and in order to make the entry into force of each block needs confirmed among 10 institutions. Block chain may allow each person can read, or is limited only by the participants, or take the hybrid route, for example, the root hash block and the API (Application Programming Interface) open to the public, API can be used to allow the outside world make inquiries and obtain information about the status of the block chain limited number. These blocks chain can be considered "section to the center."
Fully private block chain (Fully private blockchains)
Fully private block chain refers to its written permission is only in the hands of an organization block chain. Read permission or the outside world, or is any degree to the limit. Related applications include database management, auditing, and even a company, although in some cases it can hope to have a public auditability, but in many circumstances, public readability is not necessary.
>>>> Difference between the two
In general, so far there is little difference between the stressed and completely private community block chain block chains, although it is important to emphasize the significance: a combination of the former public block chain "low confidence" and to the private area block chain "single highly trusted" to provide a hybrid model, which can be more accurately described as a traditional centralized system with a certain degree of digital encryption auditable. However, to some extent, may have good reason to focus on community block chain: the fundamental value chain block completely private, in addition to encryption and authentication function of this repetitive, and there is no reason to believe that this certified seed preferred form, comprising a series of packets containing a binary Merkle tree root hash linked.
Generalized zero-knowledge proof technique (generalized zero knowledge proof technology) provides a wide range of exciting possibilities for digital encryption authentication, encryption and authentication of such application may be provided to the user. In layman's terms, I even think that, compared to the private block chain, generalized zero-knowledge proof technology in the financial world is a great place to be "underestimated" the.
Now, I will focus on the simple "public private VS" block chain discussions. First under a summary, only one block chain can survive idea is totally misleading, because both have their own advantages and disadvantages.
Advantages private block chain
The first is the private block chain, chain blocks compared to the public, it has many advantages:
If desired, the block chain running private community or company can easily modify the rules of the block chain, reducing transaction modification balances. In some cases, such as the national land registry, this function is necessary; but there is absolutely no such system that allows "terrorist pirate Roberts" in a clearly visible landowners legal title, so not trying to establish a land registration Authority controlled by the government, in practice, will not be recognized by the government itself. Of course, some would say argue that the government can give the public a backdoor key block chain stay; of course some people will argue that this approach is overkill, more efficient private block chain. About private block chain, I will be introduced later.
Verifier is disclosed
Because verification is public, so there is some miners from China for 51% of the risk of collusion reasons caused the attack.
Transaction costs cheaper
Just a few transactions are considered high power node to verify that the letter can be, rather than requiring tens of thousands of laptop confirmation, it will be cheaper transaction costs. Current public cost per transaction block chain of more than $ 0.01, this is a very worthy of attention problems, but also pay attention to the long term, with the progress of scalable Bitcoin technology that will change the the technology is expected to reduce the cost of public block chain one to two orders of magnitude, and generally efficient private system similar to the block chain.
Nodes can be well connected
Each node can be a good connection, fault quickly by manual intervention to repair, and allows the use of consensus algorithm reduces the block of time, leading to faster completion of the transaction. Block chain technology advances in public, such as Ethernet Square 1.0 concepts and subsequent proof of interest mechanism that allows public block chain to achieve "real-time trading," the goal. But the chain is still privately owned blocks will be faster, so the delay caused by the error will never disappear, as the speed of light that do not follow Moore's Law doubling every two years.
If read permission is restricted, so that the native chain blocks also provide better privacy protection.
Considering the above, the private block chain seems to look more suitable for institutional use. However, for institutions, public block chain, there are still a lot of value, which is the common block chain has been promoting freedom, neutrality and openness.
Advantages public block chain
Protect users from developer impact
In the public chain block application developers have no right to interfere with the user, so the block chain can protect them using a program developed by the user. From a naive point of view, it is indeed difficult to understand why the program developer would be willing to give up their privileges. However, the economic analysis aims to provide a more advanced two reasons: to borrow the words of Thomas Schelling, compromise is a force. First, if you explicitly choose to do something difficult or impossible, others will be more likely to trust you and interact with you, because they are confident that things are unlikely to happen to them. Second, if you are subject to coercion or other external factors can not be doing what they want to do, you may well say "Even if I wanted to, but I have no right to do it" discourse as a bargaining chip, so you can do not force you to discourage the other side is not willing to do. The main pressure or risk facing program developers, mainly from the government, so that "review the resistance", is the biggest advantage of the public block chain.
Public chain block is open, it is likely to be used by many users outside the network and produce a certain effect. For a specific example, domain hosting Take for instance. Now, if A wants to sell a domain B, there is a need to be the risk of problem solving: If A first sold the domain name, but B might not give money; money or if B, but A did not sell domain names. To solve this problem, we managed to set up a centralized agency, subject to the payment of three to six percent of the fee. However, if we have a domain name system on the block chain, chain block and use this money, then we can establish transaction fee as low as 0 Smart Contract: A sale of the domain name to the system, the system will immediately sell the domain name to First people pay money, but also because this system is built on a common block chain so trustworthy. But note that in order to make the trading process more efficient, to a completely different assets from disparate industries parked on the same public database - this is not easily done in the private block chain. The same example can be land registration and title insurance, but note that if you want to interact, to use the public can block chain validation private block chain, so that the transaction can be done through cross chain.
In some cases, these advantages do not need, but on other occasions it was so important - important enough to be worth us to wait sometimes three times to confirm the original time or pay up to $ 0.03 fee (once scalable technology become reality, only 0.0003 dollars fee). However, we should see if we can create a private contract based on the intelligent public block chain, or can cross the transaction chain between the public and private block chain, we can use the two characteristics of a good combination, as specific set of programs to choose depends on what you need the. Sometimes, the public will be relatively good, but sometimes they need a certain degree of private control. It's like a real world situation, everything needed by you.