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From PoS evolution SPoS: no energy consensus mechanism
We designed V SYSTEMS block chain platform with a focus on equity highly scalable proof (PoS) consensus mechanism, known as super node proof of interest Consensus (Supernode PoS). Features of the consensus mechanism comprises a fixed block interval coins, coin cold, and equity flowability.
This article also describes the lineage and the difference between the original Peercoin SPoS PoS mechanisms introduced in 2012.
- The role of energy
As early as 2011, the Bitcoin network may be experienced its first significant growth. At that time, the vast majority of Bitcoin users and supporters for this decentralized? Energy consumption of network problems may not care. However, Peercoin project has raised the question: to reach a consensus on energy consumption it really necessary? For most advocates of Bitcoin, the answer to this question is yes: Bitcoin is like gold; gold digging consumed energy value given to gold, and Bitcoin mining the energy consumed not only the network to reach a consensus and ensure consensus on security, but also the value of Bitcoin currency support.
But look back at history, people There are different theories for what the monetary value of gold given to this issue. Austrians concluded that it must come from some initial value of the goods. Some speculate that once the nation-state has sufficient capacity to be deprived of monetary role of gold, then gold will be worthless. As long as people believe in the effectiveness of currency Bitcoin, they will naturally ask: what in the end is to give a Bitcoin worth?
Peercoin in a certain sense in trying to unravel the mysteries of this most important currency. It successfully prove workload or (borrowed from the gold mining) mining of energy consumption were separated from the consensus algorithm, and the role of energy is limited to issuing only for digital currency. Then it is easy to examine the remaining energy associated with the issuance of currency, because people can switch to release some similar model stock, which can easily be removed from the energy component release mechanism.
Thus in fact, prove consensus equity technology further demonstrates the value of money does not come from energy consumption. Moreover, the monetary value does not need the money or any other type of commercial value. Only by the monetary value of the utility can be given.
- Proof of interest Consensus - no consensus on energy consumption
Methods Peercoin consensus groundbreaking. It is made entirely abandoned the Bitcoin amazing amount of effort proved successful consensus mechanism, try to find a completely algorithm does not depend on energy consumption. It proved that the interests be confident that this concept can be independently form a consensus algorithm, without any effort to prove the amount of ingredients.
Some authors misunderstand this. In terms of the consensus algorithm, Peercoin is proof of pure equity. The amount of workload proved only for the equitable distribution of digital currency, does not participate in the consensus algorithm.
No energy for a consensus system, we call the process of generating a block of Mint (minting), to distinguish the mining process to consume large amounts of energy.
Peercoin consensus algorithm inherited some of the features of Bitcoin. For example, it randomly generates a block, the block average can be observed only distance or spacing target block. Associated with this process is associated with a measure of the difficulty of proof called 'equity, a measure of the amount that corresponds to have a? For an adjustable threshold coins by consensus protocol maintenance.
The introduction of proof of interest is a consensus mechanism block chain technology in the development of a huge city. It not only eliminates the energy consumption to achieve a distributed consensus? Perform mining, but also greatly enhance the ability to block the expansion of the chain, paving the way for a variety of applications block chain technology.
- Criticism against the interests of consensus proved
Since the launch Peercoin groundbreaking, people often criticized for certain aspects of the system. A criticism often heard is "oppressing interests (stake grinding)". This attack shortly thereafter discovered in 2012 Peercoin after the initial release. Peercoin implemented a major new version of the algorithm in February 2013 release of 0.3 in order to resist this type of attack.
This new algorithm into a consensus field called "core (kernel)" is. It is a block chain gradually changes with consensus numbers: Protocol within a given interval of time is a selected block, the selected block may be changed one bit core. Nuclear can be seen as a source of randomness (entropy source) slowly changing on the block chain, a short block chain of bifurcation impact it brings will be very limited. With the nuclear protection of the rights and interests of the oppressed threat basically eliminated.
Another common consensus for proof of interest criticized as "risk-free fork (nothing-at-stake)" problem. The problem can be expressed as, due to the Mint does not involve effort or energy consumption, mint coins may try to block on all branches of the tree without any loss. Thus driven by the interests of those who mint coins will be conducted on all branches, in order to avoid losing a loss of competition resulting from a given fork. The problem is that this argument is that it ignores the core principles of equity certificates. Proof of interest in the idea is that when a person has an interest in the money supply in a certain proportion, he should have incentives to do good things for the entire system, the system will not attack. As a result of all the coins on the branch can be considered an attack on the agreement, it has to prove that the equity is allowed up. According to this view, even the so-called rational person should not be Mint internal monetary unit to estimate the value, but should stabilize the external value of its currency to measure the total equity.
Taking into account the possible negative impact on equity value, which may have some relevance with the tragedy of the commons. However, even as originally interpreted tragedy of the commons, a small amount of coins possible to avoid loss of equity value smaller than the magnitude of the potential loss. In fact, there is no evidence that the "risk-free fork" led to any agreement further adjusted to stop the attack made.
- Debate on cold coins
In the interests of proof available soon after consensus, Peercoin community set off a discussion of cold coins (cold minting) features. Characterized in that the bit called cold storage for credits, i.e., the private key is managed by the offline processing wallet. Since the proof of interest for those who block the consensus required to sign Mint, for its private key must be kept online. This cold storage available high security is contradictory.
The solution is to consume coins and role of phase separation. In other words, the key to the key needed coins ownership interests may be different. Then, while maintaining the key coins online, TITLE key can be placed in an offline store. This will allow the natural pools appear Mint (minting pool), similar to Bitcoin mining pool. Given the central tendency Bitcoin mining pool, the pool is not in favor of coins.
Taking into account many factors, cold coins feature is not implemented in the Peercoin. While in some other proof of interest in the system has been implemented correctly separated Mint key to ownership of the key. This separation is now commonly referred to as equity or rental agent.
- Conversion to the super node
Block chain industry has witnessed huge growth in decentralized applications in the last few years years. Bitcoin with Ethernet Square there have been periodic transaction congestion. More and more focus their attention on the performance of a single block chain.
This has brought a few questions for the design of consensus algorithm. First, mining or mint node may not have sufficient incentive to upgrade hardware node. And this node may abound. Since the maintenance cost of the entire network is very large, some nodes on hardware upgrades destined to be left behind.
Another problem with the process of generating a random bit credits related block. Although the average block interval is 10 minutes, but sometimes it produces a block to wait much longer than this time. For performance-oriented system, which has become a problem. Such systems tend fixed response time rather than randomly distributed.
As above considerations, mint protocol should be designed to have a fixed block interval and want to upgrade to nodes coins is more important than the location of the other nodes in the network.
- The right to mint coins with the competition period
To achieve the coins fixed block interval, we define a called entity mint period (minting slot) of. Each period corresponds to the time average distribution of the right coins. Therefore, in order to obtain the right to mint a certain period of time, a potential participant must take ownership of the coins of the period.
Mint defined period 60 per minute, each time period corresponds to a particular one second. To get the right coins within a second given, you must obtain ownership of coins corresponding to the second period.
Are substantially coinage system will rotate forward to the coin. The advantage of this is that if there are some super nodes stop? Stop the Mint, for whatever reason, their impact on system response and throughput will be minimized.
Each local clock supernode are synchronized via network time protocol, to ensure the normal order Mint activities. Back in mid-2009, credits selected bit network time protocol is not dependent on clock synchronization, the credits bit clock offset miners protocol allows up to 2 hours. In general, today's network time protocol can be used as a basic Internet services, and domain name service similar, so it is reasonable to assume that it has a high security.
Competition Mint period may allow freely at any time. Challengers can select a time period to challenge the current coins were. In order to prevent abuse of the challenge, the challenger to pay a higher fee challenge. When challenger publish a competitive post-trade agreement will check with the current mortgage interest in a competitor's coin to decide who is the winner of the competition.
- Mint economy
Mint Mint participation of pledge including its own interests and not rented to someone else's digital currency, and other users of digital money loaned to the Mint's. The term "lease (lease)" specified relationship Mint coins are usually run in the form of pool, and the owner needs to pay certain benefits of digital currency interest. During the loan, the money did not transfer ownership, and therefore can not spend coins on loan or transfer money.
Equal right to mint coinage time makes network super nodes have equal status and output of the same coin. This design of mining bit credits contrast. In Bitcoin mining, there is no inherent mechanism to prevent mineral pool market monopoly, it has become a real threat to the center of the target for the system.
Equal right to mint coins in the period played an indispensable Mint economic role. Super nodes form a market consisting of a pool of mint. Mint Pool market-determined interest rates on loan. Because equity owners will have to pay the equity loan rational preference supernode higher interest rates, and pay for super node high interest rates, the coin output (ie income) is fixed on loan will force more rights it reduces loan interest rates, so there is a balance point, as an inherent power to force loan interest rates super nodes tend to be equal.
V SYSTEMS platform is also used to destroy the model Peercoin fee to reduce the inflation rate, while eliminating friction between the interests of those coins.
Requirements for super node hardware resources will standardize and enhance community strength through consensus outside the scope of the agreement.
- Mobility rights and competition frequently attack
Proof of interest in the past consensus system for equity were many restrictions in movement behavior after participating in coins. While this may be reasonable to consider at the technical level, but at the economic level, it is the user involved in a coinage of barriers to entry.
However, in the interests of consensus proved, the number of equity participation coins directly related to the level of security consensus. In this sense, moving on equity without any restriction is beneficial to network security. This property does not restrict movement of said equity interests for liquidity (stake liquidity). With liquidity rights, coins can spend or transfer interests in its possession at any time. The loan interest loan people can lift the relationship at any time, and spend or transfer its rights and interests.
Liquidity equity also introduces the possibility of some attacks. From the point of view of the interests of proof should not be allowed the same rights and interests to obtain the right to mint coins in multiple periods. However, since interest has fluidity, fluidity might try using this fast-moving interests, get more coins than it should have a period of interest. This type of attack known as a frequent competition attack (busy contention attack).
Way to resist this kind of attack is to introduce some measure for the account balance, which is similar to the average cumulative periods coin competition. The idea is that equity must remain in the account for a period of time to wait for a measure to restore the account to full capacity, so you can prevent frequent attacks competition.
- Account model and balance
The traditional accounting system using the account model, it is closely monitoring a state variable called balances and the corresponding transaction history. Bit internal credits using a different form, we call coin bags (coinbag) model. Want to get account balance, you need to collect coins and bags account or information associated with the address, and the number of bags of money each currency is obtained by adding the balance. Over the past few years, many encryption systems use the currency back to a more traditional account model. V SYSTEMS account model also used, so that more effective monitoring of the balance.
After defining the lease relationship, substantially each account balance can be described as two different parts: one is Standard balance (regular balance), i.e., the user has a balance; the other is the balance of coins (minting balance), which is the standard Balance plus and minus loan balance to lease out part. These two different balance will be as easy to confirm the transaction and immediate change.
- Proposals for the balance model
10.1 Currency age
Age coin (coin age) is defined as the currency of the product of the number of wait-cycles. For example, currency day (coin-day) as a unit of currency is the product of the age of the quantity of money and the number of days to hold these currencies.
Still using the example of Peercoin white paper, if Bob receives 10 coins from Alice and hold these coins for 90 days, then we will call Bob cumulative currency coins 900 days of age. In addition, when Bob spent received money from Alice 10, Bob said to use these 10 coins accumulated currency-old has been consumed (or destroy) a.
As the value of the probability of coin control proof coins age showed its advantages and stability. However, because it is a transaction based on the amount of computational complexity and to the number of transactions executed in a given time related. Moreover, money is not an age but also reflect the exact value of the coins by size of community contribution.
10.2 Confirmed balances
It has confirmed that the balance (confirmed balance) refers to a coin balance (Balance + total standard leased - leased) after confirmed by N blocks.
Where, Bi is? Height of coins in the balance of the block i. N is used to estimate for? With a constant interval. It has confirmed that the balance of benefits include:
· Balance does not enter due to some large increases immediately, but will be reduced due to the large turn out immediately;
· To get a very? High balance has been confirmed, the miners / Mint needs a long time to collect and hold money.
However, it has been confirmed that balances itself also has disadvantages:
· In the continuous or cumulative period of time of the input does not affect the balance of this time is calculated;
· Complexity is O (N). For high-speed coin case, in order to achieve better performance and a higher stability, we need to select a large N. At this time, O (N) algorithm will be one of the factors affecting system performance.
10.3 proposals for the calculation of the balance
10.3.1 weighted average balance
To overcome the shortcomings confirmed balances and reduce computational complexity, we need to design a new high-speed mining / Mint block chain system, there is more balance model properties more easily calculated.
Learn operating system load average and ideological formulas random process, we designed the following weighted average balance:
Computational complexity of this new model of balance dropped to O (1), just record what the weighted average balance at each balance Mint changed. The fastest growth rate and the balance of the pattern is linear (see Example 11.1). However, it can be seen from Example 11.1.1 and 11.1.2 embodiment, if the balance of frequent changes, the lowering speed becomes slower weighted average balance. In addition, this is a good property as long as the overall weighted average balance controlled words. Controlled means that the balance will not somehow be created (similar to energy conservation laws in physics). Example 11.2.1 and 11.2.2 from Example balance equation can be derived weighted mean conservation law is not satisfied.
10.3.2 mint average balance
In order to have a good balance of properties of a weighted average, and overcome its shortcomings, we propose a new balance mode called mint average balance (the MAB), which is defined as follows:
Which, Bhn represents the height of the current balance at the time of hn.
The average balance is to take the coins and the weighted average of the current balance balance is less. Computational complexity is still O (1). Further, in this formula, if the user will turn out all of the balance, the MAB directly reduced to 0. With this property, the total average balance of the coins will be conserved, and is controlled by the total balance.
- Some examples
In this chapter, we will design many numerical examples are presented to demonstrate the nature of the average balance of coins. Suppose a speed of coins per block, it can be obtained in one day to 24 × 60 × 60 = 86400 blocks. In this chapter, we have taken all examples N = 86400. And as an ideal situation, we also make all transaction fees to zero.
11.1 Growth rate decrease
The first example of this chapter is one case on the balance of growth and the rate of decline.
11.1.1 simplify growth and decline rates
Alice and Bob provided initial balance are zero. Alice can obtain a credit is generated at each block, and Bob obtain the height of one-time credits on 86400 43200 blocks. Alice's growth performance available geometric series formula. Figure 1a shows the weighted average balance of the day, and Alice and Bob coins average balance performance.
Similarly, the initial balance is provided with Charlie's Dave / WAB / MAB are 86400. Charlie Each block can reduce a currency, while the 43200 block of Dave lost 86,400 coins in height. Figure 1b shows the day weighted average balance of Charlie and Dave and coins in the average balance of performance.
11.1.2 slow decline rate
Alice and Bob respectively, provided an initial weighted average balance 2000 and 12,000. Set the initial block height is odd, Bob has a balance of only 1, and Bob at the height of the block is odd in all his balances transferred to Alice. Similarly, when the height of the block is an even number, Alice will be transferred to all of the balance Bob. Figure 2 shows the case where the weighted average balance 400,000 blocks of Alice and Bob. Both can be seen in slow decline and the WAB. And if Alice and Bob during this time did not do anything, then they should be at the height of WAB sum equal to 1 is 86400.
11.2 balance conservation laws law
We will give a few examples to illustrate the nature of good coinage average balance (MAB) of.
11.2.1 conservation laws law
In this example, the initial WAB Alice and Charlie, and the balance was 100, and the initial WAB Bob and Dave and balance are both 0. When the height h = 0, Charlie turned 100 credits to Dave. In another group, Alice and Bob will block every 10,800 to exchange their balance. Figure 3 shows the total balance of each group is conserved.
11.2.2 non-conservative case
In this example, Alice initial WAB / MAB and the balance was 100, and the initial WAB Bob and Charlie's / MAB and balance are both 0. When the height h = 0, Alice turn out 80 credits to Charlie. Then, Alice and Bob to exchange every 10800 blocks balance. Figures 4a and 4b show the differences between the two balance formulas.
As it can be seen from Figure 4a total WAB within certain range in excess of 100, which means the use of certain "good" policies can create a little more WAB. However, Figure 4b shows a total MAB is always less than 100, which is a good properties in practical applications.
11.3 Mint Mint's average balance
In this example case, we will show some information on the Mint's. The first coin's initial balance 100, and the initial WAB / MAB are 0. Mint reward for every minute a coin.
Figure 5 shows the change of day WAB, MAB and balances.
The second coin's initial balance is 10,000, the initial WAB / MAB is 0. Mint reward per minute is still a coin. When a height of 500, 99,000 coin credits will in turn out of the balance.
FIGS. 6a and 6b show the WAB changes within five days, MAB and balance.
- to sum up
Supernode proof of interest Consensus (SPoS) is a process of evolution toward high-performance block chain system. Ecological resources can be more effectively tilted to upgrade hardware super node, the system does not only respond more quickly? More and more predictable, more stable. We also designed the coins in the average balance to? Support the mobility rights.