CN108416593B

CN108416593B - Block chain consensus method and system based on network dispersity certification

Info

Publication number: CN108416593B
Application number: CN201810228942.3A
Authority: CN
Inventors: 杨鉴
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-03-20
Filing date: 2018-03-20
Publication date: 2021-02-12
Anticipated expiration: 2038-03-20
Also published as: CN108416593A

Abstract

The invention relates to a block chain consensus method and a block chain consensus system based on network dispersity certification. The method comprises the following steps: the flower node sends out a broadcast signal before the transaction is released; the worker bee node generates a honey collection request according to the broadcast signal and sends the honey collection request to the flower node; when the flower node receives the first honey collection request, writing a main chain tail block address and a worker bee node address into a transaction data structure, and broadcasting the transaction; the cellular node performs accounting contention based on the contents of the past blocks, and the winner generates a new block and distributes the new block to the network. The technical scheme of the invention can realize a more environment-friendly and fairer encrypted digital currency bottom protocol.

Description

Block chain consensus method and system based on network dispersity certification

Technical Field

The invention relates to the technical field of block chains, in particular to a block chain consensus method and system based on network dispersity certification.

Background

In the block chain consensus mechanism, the Work load proving mode mainly comprises a Proof Of Work (POW) mode, and the Proof Of Work mode perfectly solves the consensus problem Of the open distribution system with its simple and direct "many-possible-to-many" logic, and is the most efficient, stable and essential Of all solutions. However, it has problems of computational competition, and energy consumption is extremely wasteful.

A Proof Of rights (POS) mode is developed on the basis Of workload proofs, core logic is developed from 'more capable' to 'more rich', accounting right competition Of a block chain only needs to be carried out among static internal states, electric power does not need to be consumed, and therefore the problem Of labor waste is effectively solved. But the rights and interests proving mode also has the problems of multiple voting, rights and interests smashing attack and the like. Because the core logic is 'richness people' and more people can get more after the same labor time is paid, the richness people tend to spend more time working, while the poor people tend to do the opposite, so that the richness people are richer, the poor people are poorer, the process is accelerated continuously, and finally the game becomes a 'noble game' of a few people. In addition, although part of the rights and interests proving protocols realize a completely fair interest system and replace mining activities, the protocols 'reward all users, namely no reward for all users', reduce the enthusiasm of all users for participating in network maintenance and enable the network to be easily attacked.

Disclosure of Invention

Aiming at the defects of the prior art and realizing a more environment-friendly and fairer encrypted digital currency underlying protocol, the invention provides a block chain consensus method and a block chain consensus system based on network dispersity certification.

In one aspect, the present invention provides a block chain consensus method based on network dispersity certification, including:

step 1, a flower node sends out a broadcast signal before transaction release;

step 2, the worker bee node generates a honey collection request according to the received broadcast signal and sends the honey collection request to the flower node;

step 3, when the flower node receives the first honey collection request, writing a main chain tail block address b and a worker bee node address m into a data structure of the transaction, and broadcasting the transaction;

step 4, the honeycomb node carries out accounting right competition based on the content of the past blocks, and the winner generates a new block and distributes the new block to the network.

In another aspect, the present invention provides a block chain consensus system based on network diversity, where the system includes a flower node, a cell node, and a worker-cell node:

the flower node is used for sending out a broadcast signal before the transaction is released;

the worker bee node is used for generating a honey collection request according to the received broadcast signal and sending the honey collection request to the flower node;

the pattern node is also used for writing a main chain tail block address b and a worker bee node address m into a data structure of the transaction and broadcasting the transaction when receiving the first honey collection request;

and the cellular node is used for carrying out accounting right competition based on the content of the past blocks, and the winner generates a new block and distributes the new block to the network.

The block chain consensus method and system based on network dispersity certification provided by the invention have the beneficial effects that no computational competition exists in the block chain consensus process, so that the energy consumption can be greatly saved; the defects of multiple voting and rights and interests smashing attack do not exist; in addition, the wealth allocation logic is optimized on the basis of rights and interests, miners replace all non-active nodes to participate in network maintenance work, and the healthy and long-term operation of the network is guaranteed; finally, it is ensured that the wealth acquisition and the workload are matched, so that the benign development of the digital currency can be promoted.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic network node diagram of a block chain consensus system based on network diversity verification according to an embodiment of the present invention;

fig. 2 is a schematic flowchart of a block chain consensus method based on network dispersity certification according to an embodiment of the present invention;

fig. 3 is a block diagram of a network structure of a block chain consensus system based on network diversity verification according to an embodiment of the present invention.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Fig. 1 is a schematic diagram of a network node of a block chain consensus system based on network diversity verification according to an embodiment of the present invention.

The system comprises a flower node representing a common user, a honeycomb node representing a miner and each worker honeycomb node attached to each honeycomb node.

1. Flower node

The broadcast source node of each transaction in the network is a flower node and is responsible for responding to the worker bee node which first initiates a honey collection request to the worker bee node. The interest of the nodes is regarded as nectar, and the amount of collected nectar affects miners, namely the competitiveness of the honeycomb nodes. The nodes of the flower also have voting power for the branches of the main chain.

2. Honeycomb node

The honeycomb node is a miner, and the worker-bee node has own worker-bee node to collect the nectar for the miner, uses the nectar to participate in accounting right competition, and also needs to complete the basic work of a common miner: verify transactions, blocks, etc. Any user may act as a cellular node.

3. Worker-bee node

Attached to each honeycomb node, the system is responsible for detecting nearby flower nodes and sending out a honey collection request as soon as possible. A request is treated as a honey harvest by the process of the nodes responding. A cellular node may have a plurality of worker-cell nodes dispersed throughout.

As shown in fig. 2, a block chain consensus method based on network diversity demonstration according to an embodiment of the present invention includes:

step 1, the flower node sends out a broadcast signal before each transaction is released.

And 2, the worker bee node generates a honey collection request according to the received broadcast signal and sends the honey collection request to the flower node.

And 3, when the flower node receives the first honey collection request, writing the main chain tail block address b and the worker bee node address m into the data structure of the transaction, and broadcasting the transaction. Namely, the successful honey collection is completed.

The transaction is acknowledged by any cellular node as being packed into a new block and the new block is broadcast to the network.

It should be noted that reference can be made to the GHOST protocol, so that the backbone is considered to follow the "heaviest" principle. In addition, a block address is used as a reference in the honey collection request of the worker bee node, but whether the block address is completely used in the worker bee node or not is completely used in the worker bee node.

The transaction data structure requires the addition of two 32 byte fields, b and m, and the entitlement size field if no account entitlement is stored elsewhere.

In other words, the honeycomb nodes continuously carry out honey collection activities in the whole network, the collected results are recorded in the blocks, and the collected honey consumption is in direct proportion to the probability of winning the accounting right; each broadcast of the nodes votes on the main chain with the rights, the result of the voting is recorded in the block, and the rights won by the block is proportional to the probability of winning.

The user votes on the main chain and the accounting node respectively with the rights and interests in each transaction, and the branches or nodes which win the most rights and interests have the highest probability of winning.

It should be noted that, in order to control the voting frequency, it is necessary to count the interval between the last transaction and the current block of each account, and take a certain granularity, for example, 10 blocks as an adjustment coefficient, starting from 0, every unit time, the coefficient increases by a certain proportion, and the interval is a longer time, for example, 6000 blocks, and the coefficient can not be restored to the maximum value after about 100 hours; also, each UTXO increases the scaling factor to scale the amount of interest in transferring frequency, and the method and parameters are the same as the former. Additionally, pure voting type transactions may be added to improve efficiency.

Because of network delay, to acquire information scattered in a network most quickly, a plurality of nodes scattered in the network must be collected together, which cannot be achieved by improving the performance of a single machine, and this is a manifestation of "capability". The embodiment of the invention can provide the capability certification protocol replacement rights and interests certification without consuming power. As many processes can not be carried out and the property of interest does not need to be got rid of, the user can freely select the right or the ability to compete for the accounting right, and the user is guided to participate through the benefit distribution rule, so that the fairness and the safety can be ensured to the maximum extent.

According to the above consensus process, the cellular node has to have more and more distributed worker-cellular nodes to obtain greater advantages in competition. Therefore, the competition mechanism can not be simulated on a single machine, and the fairness of ore excavation is ensured.

The meaning of separating the voting of the main chain from the voting of the billing right is that the right of way is determined independently. Because the cellular node contends for the user's vote on the billing right, the main-chain vote has no influence on the income of the cellular node, and the contention is not necessary, so that the attack on the branch can be effectively prevented even if the user is over concentrated.

Meanwhile, the structure of the honeycomb processing bee can be embedded in common app and webpage development, so that the problem that some developers get away from the situation that only advertisements are displayed to obtain income can be solved, or the honeycomb processing bee can contribute to enabling the app or the webpage to have better user experience.

In the embodiment, in the consensus process of the block chain, the force competition does not exist, so that the energy consumption can be greatly saved; the defects of multiple voting and rights and interests smashing attack do not exist; in addition, the wealth allocation logic is optimized on the basis of rights and interests, miners replace all non-active nodes to participate in network maintenance work, and the healthy and long-term operation of the network is guaranteed; finally, it is ensured that the wealth acquisition and the workload are matched, so that the benign development of the digital currency can be promoted.

It should be noted that, because the present embodiment is directed to a fully decentralized consensus protocol, the protocols PBFT, DPOS, Ripple, etc. are not discussed for the time being.

In order to have a stronger block-out capability, the honeycomb node will strive for more flower nodes as much as possible, although people can obtain flower honey by using more worker bees, for example, a worker bee program is embedded in the app, and in order to have more worker bees, the quality of the app must be continuously improved to win users. Inevitably, however, there will be some users who agree with each other to collaborate in a team formation to dig a mine, such as a purse or mine pool. Thus, a sort option is provided in the transaction structure, which may choose to accept worker honey in the form of a broadcast; or B, appointing a miner to directly win the vote; and even C, directing to the self and independently digging the mine. This seems to affect fairness, but in fact, in view of miners, if they can attract users by competing with each other by adjusting their allocation schemes, there will be some groups of different sizes competing with worker bees and bee cells for block right, which is also beneficial to network health development. These groups or individuals, in a similar POS pattern to compete, can effectively reduce the risk of controlling the entire network by some cells with huge worker colonies.

Preferably, the step 4 specifically includes:

and 4.1, when the honeycomb node receives the broadcasted new block, verifying the transaction, checking b and m in the transaction, marking the transaction as a billing right voting result x when m points to the honeycomb node, and marking the transaction as a main chain voting result y when b points to a current chain tail block.

And 4.2, acquiring the rights and interests of all the nodes according to the new block, and distributing the rights and interests to each transaction of all the nodes in the new block.

And 4.3, accumulating the transaction divided right number X with the X mark and the Y mark at the same time until the block is obtained, and counting the transaction divided right number Y with the Y mark in the current block. A maximum of 100 blocks are accumulated.

Regarding Y and Y, the regulations of cheating and attacking are followed.

1. Filtering transactions, miners, i.e. cellular nodes, only selecting transaction packages that are advantageous to them

Since the transactions involved in each block out may affect the subsequent competition environment, it is possible for the cellular node to attempt to obtain a more favorable location by picking up the packed transactions.

First, each block contains only a small fraction of the total number of transactions, and changing the content of one block does not have a large effect on the statistical result. To solve such problems better, the sum of rights and interests of all the nodes of the transaction packaged at this time needs to be counted as a parameter to adjust the calculation period of the next block output, and the higher the rights and interests are, the shorter the calculation period is, otherwise, the longer the calculation period is, for example, the calculation period is allowed to float between 0.9 second and 1.1 second, which directly affects the speed of the next block output. Thus, packing as many transactions as possible is a better choice, reducing the incentive for cellular nodes to do so. The parameter should be adjusted at intervals based on the average.

There may thus be a question: why do you add up the interest to reference the y-label, do not you count directly as the x-label? The problem of this article does not exist without reference to the y-mark and as such is not well understood: when the voting results of the accounting nodes are counted, the voting results of the branches are also brought in, and logically, the method has no any significance. But this has the only benefit that anyone with a wrong choice of a branch will not receive a benefit, which will encourage the user to be more cautious in choosing a branch rather than free-choice or not. Even if this would result in some statistical inaccuracies, the statistical deviations are negligible in relation to the benefits mentioned above, considering that the probability of creating a boule is not high in practical applications.

2. Also filtering transactions, but with the aim of influencing the speed of development of the branches

Since the number of transactions contained in each block-out also determines the next block-out speed of the current chain (affecting the Y parameter), an attacker can intentionally reduce the number of transactions in a branch, affecting the main chain's identification.

To solve this problem, when checking the address b in the transaction in step 4 of the consensus process, in addition to marking the transaction pointing to the end of the current chain as Y, the transactions pointing to the 2 nd and 3 rd (adjustable) blocks of the current chain are marked as Y1, and when calculating the value of Y, the transactions marked by Y and Y1 are counted simultaneously. Thus, even if an attacker impairs the block-out speed of a block, as long as the miners behind him are honest, the transactions intentionally missed by the attacker are complemented, and the transactions point to the 2+ last block of the current chain. If these trades can effectively provide the desired value of the right to the difficulty parameter, the rate of branch development will be compensated by the miners at a later time.

Here too, there may be a question: may it not be possible to count transactions with X and y1 tags while calculating the X parameter, so even if someone intentionally hands and feet the transaction while packing the tiles, there is no effect on the statistical outcome as long as miners in the next few tiles complement the transaction? The answer is no. Because of this, when a branch is generated, the node can avoid the duplicate and vote for the block before the branch to ensure that it is correct. This prevents the branch from quickly resolving the win or loss, resulting in an inability to determine the main chain in a timely manner.

A hash operation hashProof () based on a calibrated constant, such as a time stamp, a personal signature, etc., is performed at a predetermined cycle, and when hashProof () is less than target X Y, the block output requirement is satisfied, where target is the target and d is the difficulty adjustment parameter.

During which if multiple competing blocks are received, they can be processed in parallel. In order not to weaken the main chain, competition at the current chain is not stopped as long as the weight of the main chain does not exceed the current chain +8, which also meets the self-interest because it is possible to become the main chain.

It should be noted that the computation cycle may fluctuate according to the rules of the cheating and attacking.

And 4.4, when the block output requirement is met, generating the packaged file according to the transaction received in the calibration time period, and broadcasting the packaged file to the whole network.

Preferably, the package file specifically includes: the transactions received during the calibration period, the id information for all transactions with x-tags and y-tags, and the revenue for each flower node and cell node.

Wherein the id information of the transaction (which may be coded over 100 blocks to save space) is used for authentication with the honeycomb nodes and other computational parameters, such that the gains from mining are proportionally distributed by the honeycomb nodes and all the flower nodes with x-label and y-label.

With respect to the allocation scheme, the provisions for revenue allocation are followed.

If the distribution strategy is different, the user can cause the change of the network structure and the individual behavior under the driving of the benefit. The allocation here refers to the allocation obtained by digging the mine in the A class, and the allocation of the B class and the C class is completely completed by miners.

1. In order to avoid the cellular nodes from gaining more benefit after splitting themselves, the cellular nodes should be split according to a fixed ratio of the total amount.

2. The assignment weight of the equity may influence the choice of the user, and if it is fully assigned in the equity, an absolutely fair assignment mechanism may not be enough to attract more general users to participate, but if the equity weight is too low, too many high equity users are lost.

3. After the proportion of rights and interests is reduced, in order to avoid the situation that a user can infinitely split the account of the user to obtain more benefits, the handling fee is required to be used as a reference basis, and therefore more optional strategies can be provided for the users with different requirements to play a role in adjustment.

The class a mining allocation scheme is therefore preferably influenced by two parameters, such as the benefits and the commission: miners and wallets are divided into 30% of the total profit, the remainder is divided into two parts, 1/3 for commission and 2/3 for equity. The interest here refers to the interest accumulated to the X parameter, and each flower node can be repeatedly calculated.

The user's default commission for different voting schemes may be adjusted based on the average number of people n who participated in the block each time that both users took part in the block at the previous time period A, B. The fewer the number of people, the more miners, the lower the transaction fee, attract more users to match the number of miners. In fact, even without the above adjustments, the economic laws naturally allow people to make a similar balance, but only a little slower. In addition, for A-type ore excavation, honeycomb nodes can be adjusted simultaneously according to n to be divided into proportions: the number of people is small, the dividing proportion is reduced, more users are attracted to select the mode A, the number of honeycomb nodes can be reduced, and the adjustment of the network structure is accelerated.

In addition, the extra space occupied by the data regarding the authentication parameters and the revenue allocation amounts to at most 2 bytes of id and 4 bytes of revenue for each transaction, which is well within the acceptable range. The extra work to verify the blocks or confirm the transaction is to traverse up to the first 100 blocks without causing excessive workload.

For the 51% challenge problem. If a user has more than 50% of the resources in his pool, the system is completely under his control, as is the case with other algorithms. With regard to the extent to which a user who knows 50% or less of resources can launch an attack, the foregoing setting is temporarily used, the block leaving period is 60 seconds, 6000 block intervals are the right recovery period, and then the right of total 1/6000 is given to each block on average, and 100 blocks are taken as the statistical interval, so that the right of (1/6000) × 100 ═ 1/60 is given to compete each block on average. To control out-of-block rights, it is only necessary to place a rights greater than 1/120 in each block. Assuming a user has 50% of his rights and has all accumulated for more than 100 hours, he can be assured that a double flower attack can be successfully performed within (50%)/(1/120) — 60 blocks. Thus if there is a very important transaction, waiting 1 hour before confirmation, absolute security can be guaranteed.

The 100 block statistic interval is a very conservative design, and is temporarily set to 100 blocks in order to prevent bottleneck in verifying the blocks and trading. In fact, according to the current search speed level of the database, a large promotion space is provided as long as the proper design is carried out. If the system can be increased to 1000 blocks as a statistical interval, the security of the system can be increased by 10 times, and so on.

In order to simulate worker bee nodes, a large number of worker bee nodes are simulated and created to access a plurality of opposite terminals in a p2p network, so that the probability of successful honey collection is improved. In order to deal with the situation, control can be performed when the p2p connection is created, for example, each user terminal only needs to establish connection with the first M worker-bee nodes with the highest response speed.

As shown in fig. 3, a block chain consensus system based on network diversity verification according to an embodiment of the present invention includes a flower node, a cell node, and a worker-cell node:

and the flower node is used for sending out a broadcast signal before each transaction is issued.

And the worker bee node is used for generating a honey collection request according to the received broadcast signal and sending the honey collection request to the flower node.

And the pattern node is also used for writing the main chain tail block address b and the worker bee node address m into the data structure of the transaction and broadcasting the transaction when receiving the first honey collection request.

Preferably, the cellular node is specifically configured to:

for validating the transaction and checking b and m in the transaction upon receipt of the new block broadcast, marking the transaction as a billing authority vote result x when m points to the cell node itself and as a main chain vote result y when b points to the current chain end block.

And acquiring the weight number of all the flower nodes according to the new block, and distributing the weight number to each transaction of all the flower nodes in the new block in an average manner.

Accumulating the transaction divided weight number X with the X mark and the Y mark at the same time until the block is obtained, and counting the transaction divided weight number Y with the Y mark in the current block.

And performing hash operation hashProof () based on a calibration constant in a preset period, and meeting the block requirement when hashProof () is less than target X d X Y, wherein target is a target and d is a difficulty adjusting parameter.

And when the block output requirement is met, generating the packaged file according to the transaction received in the calibration period, and broadcasting the packaged file to the whole network.

Preferably, the cellular node is specifically configured to: and packaging the transactions received in the calibration period, the id information of all the transactions with the x mark and the y mark, and the profits of each flower node and the honeycomb node into the packaging file.

The reader should understand that in the description of this specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example" or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A block chain consensus method based on network dispersity certification, the method comprising:

step 1, a flower node sends out a broadcast signal before transaction release;

the transaction is confirmed by any cellular node to be packed into a new block and the new block is broadcast to the network;

step 4, carrying out accounting right competition by the honeycomb nodes based on the content of the past blocks, generating a packaged file by the winning honeycomb node, and issuing the packaged file to a network;

the flower nodes are broadcast source nodes of each transaction in the network, the honeycomb nodes represent miners, and the worker-honeycomb nodes are attached to each honeycomb node;

the step 4 specifically includes:

step 4.1, when the broadcasted new block is received, the transaction is verified, b and m in the transaction are checked, when m points to a honeycomb node, the transaction is marked as a billing right voting result x, and when b points to a current chain tail block, the transaction is marked as a main chain voting result y;

step 4.2, acquiring the rights and interests of all the nodes according to the new block, and distributing the rights and interests to each transaction of all the nodes in the new block;

4.3, accumulating the transaction divided right number X with the X mark and the Y mark at the same time until the block output requirement is met, and counting the transaction divided right number Y with the Y mark in the current block; filtering the transaction according to the rights X and the rights Y;

and 4.4, when the block is output, generating a packaged file according to the transaction received in the calibration time period, and broadcasting the packaged file to the whole network.

2. The method of claim 1, wherein the block chain consensus based on the net dispersion degree certification is achieved by: and performing a hash operation hashProof () based on a calibration constant in a preset period, and when hashProof () < target X d X Y, achieving the block requirement, wherein target is a target interest value, and d is a difficulty adjustment parameter, wherein the target interest value is an interest value of a transaction directed to the 2 nd block from the last of the current chain.

3. The method of claim 2, wherein the calibration constant is a timestamp or a personal signature.

4. The method of claim 1, wherein the packaging file specifically comprises: the transactions received during the calibration period, the id information for all transactions with x-tags and y-tags, and the revenue of the nodes of the flower and cell.

5. The blockchain consensus method based on the proof of network divergence according to any one of claims 1 to 4, wherein each flower node establishes a link with only a calibrated number of worker bee nodes that respond the fastest to the flower node when receiving the honey collection request.

6. The method of any of claims 1 to 4, wherein the data structure of the transaction includes a classification option for the cellular node to select, the classification option includes A, B and C:

the method comprises the following steps that an option A is used for receiving honey collected by worker bee nodes in a broadcasting mode, an option B is used for directly enabling designated bee nest nodes to win votes, and an option C is used for pointing to the bee nest nodes to independently dig mines.

7. A block chain consensus system based on network diversity, the system comprising a flower node, a cell node, and an industrial cell node:

a cellular node for packaging the transaction acknowledgement into a new block and broadcasting the new block to a network;

the honeycomb nodes are also used for carrying out accounting right competition based on the content of the past blocks, and the winning honeycomb nodes generate a packaged file and issue the packaged file to the network;

the cellular node is specifically configured to:

upon receiving the new block broadcast, validating the transaction and checking b and m in the transaction, when m points to the cell node itself, marking the transaction as a billing right voting result x, and when b points to the current chain end block, marking the transaction as a main chain voting result y;

acquiring the weight number of all the flower nodes according to the new block, and distributing the weight number to each transaction of all the flower nodes in the new block respectively in an average manner;

accumulating the transaction divided right number X with the X mark and the Y mark at the same time until the block output requirement is met, and counting the transaction divided right number Y with the Y mark in the current block; filtering the transaction according to the rights X and the rights Y;

and when the block is output, generating a packaged file according to the transaction received in the calibration time period, and broadcasting the packaged file to the whole network.

8. The system of claim 7, wherein the block chain consensus requirement is achieved by: and performing a hash operation hashProof () based on a calibration constant in a preset period, and when hashProof () < target X d X Y, achieving the block requirement, wherein target is a target interest value, and d is a difficulty adjustment parameter, wherein the target interest value is an interest value of a transaction directed to the 2 nd block from the last of the current chain.