CN108282334B - A multi-party key agreement device, method and system based on blockchain - Google Patents

Abstract

The present invention provides a blockchain-based multi-party key agreement device, method and system, the device includes: at least two participating nodes and a verification node; wherein each participating node is used to send a zone to an external BaaS platform Block chain service application; obtain the block chain allocated by the BaaS platform according to the block chain service application; generate the first smart contract according to the domain parameters and generators and the random number generated by itself, and send the first smart contract to the block chain middle; obtain the second smart contract issued by other participating nodes from the blockchain, generate a third smart contract according to the first smart contract and the second smart contract, and publish the third smart contract to the blockchain; verify The node is used to execute the current smart contract in the blockchain, so that each participating node reaches a consensus; wherein, the current smart contract includes: any one of the first smart contract, the second smart contract and the third smart contract. This scheme can improve the efficiency of multi-party key negotiation.

Description

A multi-party key agreement device, method and system based on blockchain

technical field

The present invention relates to the field of computer technology, in particular to a block chain-based multi-party key agreement device, method and system.

Background technique

Key agreement is a key establishment technology. Two or more participants in the system jointly provide information, and then each participant can deduce a result that cannot be predetermined by any participant based on the information provided by other participants. Then each participant shares data according to the shared key to ensure data security.

At present, during multi-party negotiation, each participant needs to obtain the information provided by all other participants before calculating the corresponding shared key. For example, when the participants in the system are A, B, and C, A needs to obtain the information provided by B and C to determine its corresponding shared key, and A needs to provide its corresponding information to B and C so that B and C can calculate the shared key.

When the number of participants participating in the key negotiation is large, when the key negotiation is performed in the above manner, each participant needs to perform a large amount of information exchange and calculation process, so that the efficiency of the multi-party key negotiation is low.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a blockchain-based multi-party key negotiation device, method and system, which can improve the efficiency of multi-party key negotiation.

In a first aspect, an embodiment of the present invention provides a blockchain-based multi-party key agreement device, including: at least two participating nodes and a verification node; wherein,

Each of the participating nodes is used to send a blockchain service application to an external blockchain-as-a-service BaaS platform; obtain the blockchain allocated by the BaaS platform according to the blockchain service application; parameters, generators and random numbers generated by itself, generate a first smart contract, and send the first smart contract to the blockchain; obtain the at least two participating nodes from the blockchain The second smart contract published by other participating nodes, generate a third smart contract according to the first smart contract and the second smart contract, and publish the third smart contract to the blockchain;

The verification node is used to execute the current smart contract in the blockchain, so that each of the participating nodes reaches a consensus; wherein, the current smart contract includes: the first smart contract, the second smart contract and the any one of the third smart contracts.

Preferably,

Each of the participating nodes is used to calculate the first smart contract using the following calculation formula;

Wherein, Ni represents the first smart contract corresponding to the _ith participating node; g represents the generator, ri represents the random number generated by the _ith participating node, and a represents the domain parameter;

Preferably,

Each of the participating nodes is used to calculate the third smart contract using the following calculation formula;

Among them, M _ij represents the third smart contract corresponding to the i-th participating node, g represents the generator, ri represents the random number generated by the _i -th participating node, and t _j represents the j-th other The second smart contract sent by the participating nodes, i≠j, a characterizes the domain parameters.

Preferably,

Each of the participating nodes is used to determine whether the unacquired second smart contract exists in the blockchain, and if so, obtain the unacquired second smart contract from the blockchain , and generate a third smart contract according to the acquired second smart contract and the first smart contract, otherwise, publish the third smart contract to the blockchain as a negotiated key.

Preferably,

Each of the participating nodes is further configured to obtain the negotiated key from the blockchain, and use the negotiated key for data transmission.

In a second aspect, an embodiment of the present invention provides a method for performing key negotiation using the blockchain-based multi-party key agreement device provided by any of the foregoing embodiments, including:

Send a blockchain service application to an external blockchain-as-a-service BaaS platform;

Obtain the blockchain allocated by the BaaS platform according to the blockchain service application;

Use each participating node to generate a first smart contract according to preset domain parameters and generators and random numbers generated by itself, and send the first smart contract to the blockchain;

Using each of the participating nodes to obtain the second smart contracts issued by other participating nodes from the blockchain;

Utilize each of the participating nodes to generate a third smart contract according to the first smart contract and the second smart contract, and publish the third smart contract to the blockchain;

The current smart contract in the blockchain is executed by the verification node, so that each of the participating nodes reaches a consensus; wherein, the current smart contract includes: the first smart contract, the second smart contract and the third smart contract Any of the smart contracts.

Preferably,

Described using each participating node to generate the first smart contract according to the preset domain parameters and generator and the random number generated by itself, including:

Calculate the first smart contract using the following calculation formula;

Wherein, Ni represents the first smart contract corresponding to the _ith participating node; g represents the generator, ri represents the random number generated by the _ith participating node, and a represents the domain parameter;

Preferably,

The generating a third smart contract according to the first smart contract and the second smart contract includes:

Use the following calculation formula to calculate the third smart contract;

Among them, M _ij represents the third smart contract corresponding to the i-th participating node, g represents the generator, ri represents the random number generated by the _i -th participating node, and t _j represents the j-th other The second smart contract sent by the participating nodes, i≠j, a characterizes the domain parameters.

Preferably,

After the using each of the participating nodes to obtain the second smart contract issued by the other participating nodes from the blockchain, the method further includes:

Determine whether there is the second smart contract that has not been acquired in the blockchain, and if so, acquire the second smart contract that has not been acquired from the blockchain, and based on the acquired second smart contract The smart contract and the first smart contract generate a third smart contract, otherwise, the third smart contract is published in the blockchain as a negotiated key.

Preferably,

After the third smart contract is published in the blockchain as the negotiated key, the method further includes:

Use each of the participating nodes to obtain the negotiated key from the blockchain;

Data transmission is performed using the negotiated key.

In a third aspect, an embodiment of the present invention provides a blockchain-based multi-party key agreement system, including: the multi-party key agreement device provided by any of the foregoing embodiments of the present invention, and a blockchain-as-a-service BaaS platform; wherein ,

The BaaS platform is configured to allocate a blockchain to the multi-party key agreement device according to the blockchain service application sent by the multi-party key agreement device.

Preferably,

the multi-party key agreement device, configured to obtain the negotiated key from the blockchain;

The BaaS platform is further configured to release the blockchain after the multi-party key agreement apparatus obtains the negotiated key.

Embodiments of the present invention provide a blockchain-based multi-party key agreement device, method, and system. Each participating node first obtains the blockchain allocated by a blockchain as a service (Blockchain as a Service, BaaS) platform, and then each Participating nodes publish their corresponding intermediate results (first smart contract or third smart contract) to the blockchain, and can obtain intermediate results (second smart contracts) published by other participating nodes from the blockchain. For example, when the participating nodes are A, B, and C, A, B, and C calculate their corresponding first smart contracts (a1, b1, and c1, respectively), and then publish the first smart contracts to the blockchain. , B can obtain c1 issued by C from the blockchain, calculate the third smart contract b1c1 according to c1 and b1, and publish the calculated b1c1 to the blockchain, then A can obtain b1c1 from the blockchain, Combined with a1, the corresponding third smart contract a1b1c1 is calculated and released to the blockchain. It can be seen from this that the participating nodes do not need to obtain information from each other participating nodes separately, but can directly obtain the intermediate results from the blockchain. In this example, participating node A does not need to obtain b1 and c1 from B and C, respectively. , but directly obtains the intermediate result b1c1 from the blockchain, which reduces the information exchange and calculation process in the key negotiation process, thereby improving the efficiency of multi-party key negotiation.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic structural diagram of a blockchain-based multi-party key agreement device provided by an embodiment of the present invention;

2 is a flowchart of a blockchain-based multi-party key agreement method provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a blockchain-based multi-party key agreement system provided by an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are protected by the present invention. scope.

As shown in FIG. 1 , an embodiment of the present invention provides a blockchain-based multi-party key agreement device, the device may include: at least two participating nodes 101 and verification nodes 102; wherein,

Each of the participating nodes 101 is configured to send a blockchain service application to an external blockchain-as-a-service BaaS platform; obtain the blockchain allocated by the BaaS platform according to the blockchain service application; Domain parameters, generators and random numbers generated by itself, generate a first smart contract, and send the first smart contract to the blockchain; obtain the at least two participating nodes from the blockchain The second smart contract published by other participating nodes in the , generates a third smart contract according to the first smart contract and the second smart contract, and publishes the third smart contract to the blockchain;

The verification node 102 is configured to execute the current smart contract in the blockchain, so that each of the participating nodes reaches a consensus; wherein, the current smart contract includes: the first smart contract, the second smart contract and any one of the third smart contracts.

Each participating node first obtains the blockchain allocated by the BaaS platform, and then each participating node publishes its corresponding intermediate result (first smart contract or third smart contract) to the blockchain, and can obtain other Intermediate results (second smart contracts) published by participating nodes. The validating node then automatically executes the current smart contract so that the corresponding participating nodes can reach a consensus. For example, when the participating nodes are A, B, and C, A, B, and C calculate their corresponding first smart contracts (a1, b1, and c1, respectively), and then publish the first smart contracts to the blockchain. , B can obtain c1 issued by C from the blockchain, calculate the third smart contract b1c1 according to c1 and b1, and publish the calculated b1c1 to the blockchain, then A can obtain b1c1 from the blockchain, Combined with a1, the corresponding third smart contract a1b1c1 is calculated and released to the blockchain. It can be seen from this that the participating nodes do not need to obtain information from each other participating nodes separately, but can directly obtain the intermediate results from the blockchain. In this example, participating node A does not need to obtain b1 and c1 from B and C, respectively. , but directly obtains the intermediate result b1c1 from the blockchain, which reduces the information exchange and calculation process in the key negotiation process, thereby improving the efficiency of multi-party key negotiation.

In an embodiment of the present invention, each of the participating nodes 101 is used to determine whether there is the unacquired second smart contract in the blockchain, and if so, obtain the unacquired second smart contract from the blockchain the acquired second smart contract, and generate a third smart contract according to the acquired second smart contract and the first smart contract, otherwise, publish the third smart contract to the district as a negotiated key in the blockchain.

计算出其对应的第一智能合约，其中，N_i表征P_i对应的第一智能合约；g表征所述生成元，r_i表征P_i产生的随机数，a表征域参数，并将第一智能合约发布到区块链中。参与节点P_i可根据区块链中其他参与节点P_j发布的中间结果r_j(i≠j)，利用公式

计算第三智能合约，其中，M_ij表征第i个所述参与节点对应的第三智能合约，g表征所述生成元，r_i表征第i个所述参与节点产生的随机数，t_j表征第j个所述其他参与节点发送的第二智能合约，i≠j，a表征所述域参数。Here, after the BaaS platform allocates and provides blockchain services, the participating nodes participating in the key negotiation disclose domain parameters and generators, generate smart contracts and publish them in the blockchain. Then each participating node P _i (assuming there are n participating nodes, _i <n) generates a random number ri , and then according to the formula

Calculate the corresponding first smart contract, wherein, Ni represents the first smart contract corresponding to _Pi ; _g represents the generator, _ri represents the random number generated by _Pi , a represents the domain parameter, and the first Smart contracts are published into the blockchain. Participating node P _i can use the formula according to the intermediate results r _j (i≠j) published by other participating nodes P _j in the blockchain.

Calculate the third smart contract, wherein M _ij represents the third smart contract corresponding to the i-th participating node, g represents the generator, ri represents the random number generated by the _i -th participating node, and t _j represents the The second smart contract sent by the jth other participating node, i≠j, a represents the domain parameter.

并将其发布到区块链中。循环执行该计算过程，直至区块链中不存在P_i未获取过的中间结果，即P_i得到M_x…y，其中，x…y包括1至n中除i以外的n-1个值，再结合r_i计算出

得到最终的协商密钥，并将该协商密钥发布到区块链中。Publish the determined third smart contract to the blockchain, and the verification node automatically executes the smart contract, then P _i and P _j reach a consensus. At the same time as P _i is calculated, other participating nodes are also performing the same calculation according to the intermediate results published in the blockchain, and publish the calculation results to the blockchain, then P _i can use the intermediate results published in the blockchain. Continue to calculate. In this process, Pi first determines whether there is an intermediate result (second smart contract) M _xy (1≤x< _y≤n ) published by other participating nodes in the blockchain, and if so, recalculates the first result according to M _xy Three smart contracts

and publish it to the blockchain. The calculation process is executed cyclically until there is no intermediate result that Pi has not obtained in the blockchain, that is, _Pi obtains M _x...y , where x...y includes n-1 values from 1 to n except for _i , and then combined with _ri to calculate

Get the final negotiated key and publish the negotiated key to the blockchain.

For example, when the participating nodes are A, B, C and D, D also publishes the first smart contract d1 calculated by itself to the blockchain. After A obtains the intermediate result b1c1 published by B, it calculates a1b1c1, Then it is determined that there is still d1 that it has not acquired in the blockchain. At this time, A continues to acquire d1, and then recalculates the third smart contract a1b1c1d1 according to the acquired d1. At this time, there is no unacquired d1 in the blockchain. The intermediate result, a1b1c1d1 is the final negotiation key. As a result, each participating node obtains the intermediate results calculated by other participating nodes from the blockchain, and uses the intermediate results to continue the calculation, thereby reducing the information exchange and calculation process in the key negotiation process, thereby improving the multi-party key. Efficiency of negotiation. At the same time, the blockchain technology is used to effectively ensure the security of data.

To sum up, each participating node participating in the key negotiation maintains a ledger (blockchain) through the P2P consensus network. The public parameters of the key negotiation and the intermediate results of the key negotiation are recorded in the ledger. Participate in the mutual cooperation between nodes to complete the key agreement task. Among them, each participating node writes the smart contract into the blockchain through the consensus network through the BaaS platform that provides basic blockchain services, and the verification node in the consensus network executes the smart contract. Each participating node uses the Diffie-Hellman algorithm to generate intermediate data, generate smart contracts and publish them to the blockchain. The verification node is responsible for executing the smart contract and feeding back the execution results to each participating node. The BaaS platform provides basic blockchain services. There is no need to provide trusted services, only blockchain infrastructure needs to be provided.

In addition, in the process of the verification node executing the smart contract, if there is an abnormality, it will terminate the smart contract, send a transaction failure notification, and update the execution status. Otherwise, after the smart contract execution is completed, the execution status will be updated.

In an embodiment of the present invention, each of the participating nodes is further configured to obtain the negotiated key from the blockchain, and use the negotiated key for data transmission. After each participating node determines the same negotiated key, subsequent data transmission can be performed according to the negotiated key to ensure data security.

As shown in FIG. 2 , an embodiment of the present invention provides a method for performing key negotiation using the blockchain-based multi-party key agreement apparatus provided by any of the foregoing embodiments, and the method may include the following steps:

Step 201: Send a blockchain service application to an external blockchain-as-a-service BaaS platform;

Step 202: Obtain the blockchain allocated by the BaaS platform according to the blockchain service application;

Step 203: using each participating node to generate a first smart contract according to preset domain parameters and generators and random numbers generated by itself, and send the first smart contract to the blockchain;

Step 204: using each of the participating nodes to obtain the second smart contract issued by other participating nodes from the blockchain;

Step 205: using each of the participating nodes to generate a third smart contract according to the first smart contract and the second smart contract, and publishing the third smart contract to the blockchain;

Step 206: Use the verification node to execute the current smart contract in the blockchain, so that each of the participating nodes reaches a consensus; wherein, the current smart contract includes: the first smart contract, the second smart contract and all any one of the third smart contracts mentioned above.

In an embodiment of the present invention, the specific implementation of step 203 may include:

Calculate the first smart contract using the following calculation formula;

Wherein, Ni represents the first smart contract corresponding to the _ith participating node; g represents the generator, ri represents the random number generated by the _ith participating node, and a represents the domain parameter;

In an embodiment of the present invention, the specific implementation of step 205 may include:

Use the following calculation formula to calculate the third smart contract;

Among them, M _ij represents the third smart contract corresponding to the i-th participating node, g represents the generator, ri represents the random number generated by the _i -th participating node, and t _j represents the j-th other The second smart contract sent by the participating nodes, i≠j, a characterizes the domain parameters.

In an embodiment of the present invention, after step 204, it may further include:

Determine whether there is the second smart contract that has not been acquired in the blockchain, and if so, acquire the second smart contract that has not been acquired from the blockchain, and based on the acquired second smart contract The smart contract and the first smart contract generate a third smart contract, otherwise, the third smart contract is published in the blockchain as a negotiated key.

In an embodiment of the present invention, after step 205, it may further include:

Use each of the participating nodes to obtain the negotiated key from the blockchain;

Data transmission is performed using the negotiated key.

Since the information exchange and execution process among the steps in the above method are based on the same concept as the device embodiments of the present invention, the specific content can be found in the descriptions in the device embodiments of the present invention, which will not be repeated here.

As shown in FIG. 3 , an embodiment of the present invention provides a blockchain-based multi-party key agreement system, including: a multi-party key agreement device 301 provided by any of the above embodiments of the present invention, and a blockchain-as-a-service BaaS platform 302; wherein,

The BaaS platform 302 is configured to allocate a blockchain to the multi-party key agreement device according to the blockchain service application sent by the multi-party key agreement device 301 .

In an embodiment of the present invention, the multi-party key agreement apparatus 301 is configured to obtain the negotiated key from the blockchain;

The BaaS platform 302 is further configured to release the blockchain after the multi-party key agreement apparatus obtains the negotiated key.

After the key negotiation process is over, the BaaS platform releases the applied blockchain service infrastructure resources, so that the blockchain can be recycled after the key negotiation process, which is conducive to the effective use of resources.

An embodiment of the present invention provides a readable medium, including an execution instruction. When a processor of a storage controller executes the execution instruction, the storage controller executes the method provided by any of the foregoing embodiments of the present invention.

An embodiment of the present invention further provides a memory controller, including: a processor, a memory, and a bus; the memory is used for storing execution instructions, the processor and the memory are connected through the bus, and when the memory controls When the processor is running, the processor executes the execution instructions stored in the memory, so that the memory controller executes the video processing method provided by any of the foregoing embodiments of the present invention.

To sum up, the above embodiments of the present invention at least have the following beneficial effects:

1. In the embodiment of the present invention, each participating node first obtains the blockchain allocated by the BaaS platform, and then each participating node publishes its corresponding intermediate result (the first smart contract or the third smart contract) to the blockchain, And can obtain the intermediate results (second smart contracts) issued by other participating nodes from the blockchain, and determine the third smart contract according to the obtained intermediate results, thereby reducing the information exchange and calculation process in the key negotiation process, Thus, the efficiency of multi-party key negotiation is improved.

2. In the embodiment of the present invention, each participating node participating in the key negotiation jointly maintains a blockchain through the P2P consensus network, records the public parameters of the key negotiation and the intermediate result of the key negotiation through the blockchain, and executes the smart contract. Realize the mutual cooperation among the participating nodes and complete the key agreement task. By using blockchain technology, the security of data is effectively guaranteed.

3. In this embodiment of the present invention, after each participating node determines the same negotiated key, each participating node can perform subsequent data transmission according to the negotiated key to ensure data security.

4. In the embodiment of the present invention, after the key negotiation process is over, the BaaS platform releases the applied blockchain service infrastructure resources, so that the blockchain is recycled after the key negotiation process, which is conducive to the effective use of resources.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply a relationship between these entities or operations. There is no such actual relationship or sequence. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, the inclusion of an element by the phrase "comprising a..." does not preclude the presence of additional such elements in the process, method, article or apparatus that includes the element.

Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by program instructions related to hardware, the aforementioned program can be stored in a computer-readable storage medium, and when the program is executed, execute It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other mediums that can store program codes.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention, and are only used to illustrate the technical solutions of the present invention, but not to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (8)

1. A multi-party key agreement apparatus based on block chains, comprising: at least two participating nodes and a verifying node; wherein,

each participating node is used for sending a block chain service application to an external block chain service (BaaS) platform; acquiring a block chain distributed by the BaaS platform according to the block chain service application; generating a first intelligent contract according to a preset domain parameter, a generating element and a random number generated by the generating element, and sending the first intelligent contract to the block chain; acquiring second intelligent contracts issued by other participating nodes in the at least two participating nodes from the block chain, generating third intelligent contracts according to the first intelligent contracts and the second intelligent contracts, and issuing the third intelligent contracts to the block chain;

the verification node is used for executing the current intelligent contract in the block chain so as to enable all the participating nodes to achieve consensus; wherein the current intelligent contract comprises: any one of the first intelligent contract, the second intelligent contract, and the third intelligent contract;

each participating node is configured to determine whether the second intelligent contract which is not acquired exists in the block chain, if so, acquire the second intelligent contract which is not acquired from the block chain, and generate a third intelligent contract according to the acquired second intelligent contract and the first intelligent contract, otherwise, issue the third intelligent contract as a negotiation key to the block chain;

each of the participating nodes is further configured to obtain the negotiation key from the block chain, and perform data transmission by using the negotiation key.

2. The apparatus of claim 1,

each of the participating nodes is used for calculating the first intelligent contract by using the following calculation formula;

wherein N is_iCharacterizing a first intelligent contract corresponding to the ith participating node; g characterizing the generator, r_iCharacterizing the random number generated by the i-th of the participating node, a characterizing the domain parametersCounting;

and/or the presence of a gas in the gas,

each of the participating nodes is used for calculating the third intelligent contract by using the following calculation formula;

wherein M is_ijCharacterizing a third intelligent contract corresponding to the ith participating node, g characterizing the generator, r_iCharacterizing the random number, t, generated by the ith of said participating node_jAnd characterizing a second intelligent contract sent by the jth other participating node, i ≠ j, and a characterizes the domain parameter.

3. A method for performing key agreement by using the device for block chain based multi-party key agreement according to any one of claims 1 to 2, comprising:

sending a block chain service application to an external block chain service (BaaS) platform;

acquiring a block chain distributed by the BaaS platform according to the block chain service application;

generating a first intelligent contract by using each participating node according to a preset domain parameter, a generating element and a random number generated by the participating node, and sending the first intelligent contract to the block chain;

acquiring a second intelligent contract issued by other participating nodes from the block chain by utilizing each participating node;

generating a third intelligent contract according to the first intelligent contract and the second intelligent contract by utilizing each participating node, and issuing the third intelligent contract into the block chain;

executing a current intelligent contract in the block chain by utilizing a verification node so as to enable all the participating nodes to achieve consensus; wherein the current intelligent contract comprises: any one of the first intelligent contract, the second intelligent contract, and the third intelligent contract.

4. The method of claim 3,

the generating of the first intelligent contract by using each participating node according to the preset domain parameter, the generating element and the random number generated by the participating node comprises:

calculating the first intelligent contract by using the following calculation formula;

wherein N is_iCharacterizing a first intelligent contract corresponding to the ith participating node; g characterizing the generator, r_iCharacterizing the random number generated by the ith said participating node, a characterizing said domain parameter;

and/or the presence of a gas in the gas,

the generating a third intelligent contract according to the first intelligent contract and the second intelligent contract comprises:

calculating the third intelligent contract by using the following calculation formula;

wherein M is_ijCharacterizing a third intelligent contract corresponding to the ith participating node, g characterizing the generator, r_iCharacterizing the random number, t, generated by the ith of said participating node_jAnd characterizing a second intelligent contract sent by the jth other participating node, i ≠ j, and a characterizes the domain parameter.

5. The method of claim 4,

after the acquiring, by each participating node, the second intelligent contracts issued by other participating nodes from the blockchain, the method further includes:

and determining whether the second intelligent contract which is not acquired exists in the block chain, if so, acquiring the second intelligent contract which is not acquired from the block chain, and generating a third intelligent contract according to the acquired second intelligent contract and the first intelligent contract, otherwise, issuing the third intelligent contract serving as a negotiation key to the block chain.

6. The method of claim 5,

after the issuing of the third smart contract as a negotiated key into the blockchain, further comprising: acquiring the negotiation key from the block chain by using each participating node;

and carrying out data transmission by utilizing the negotiation key.

7. A multi-party key agreement system based on block chains, comprising: the multi-party key agreement device of any one of claims 1 to 2, and a blockchain as a service, BaaS, platform; wherein,

the BaaS platform is configured to allocate a block chain to the multi-party key agreement device according to a block chain service application sent by the multi-party key agreement device.

8. The system of claim 7,

the multi-party key negotiation device is used for acquiring a negotiation key from the block chain;

the BaaS platform is further configured to release the block chain after the multi-party key agreement device obtains the agreement key.

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