Dynamic trust based blockchain rewriting method for supporting update traceability

Abstract

The application discloses a dynamic trust-based blockchain rewriting method supporting update traceability, which is applied to an editable blockchain system, and comprises the following steps: a modifier broadcasts a modification suggestion to other committee members in the rth round; the committee members in the rth round are obtained through election based on trust values of each user at the rth moment; the trust value of the user node at the rth moment is determined according to historical transactions, consensus and modification behaviors; other committee members verify the modification suggestion; if the verification is passed, other committee members accept the modification of the original information by the modifier and replace the original information with modified information on the editable global ledger, and save the modified signature and the modified random number. The application can improve the security performance of the editable blockchain system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of blockchains, and particularly relates to a dynamic trust-based blockchain rewriting method supporting update of traceability. BACKGROUND

[0002] Recently, investigations and applications of blockchain technology have attracted extensive attention from academia and industry, showing explosive growth. Blockchain combines cryptography, distributed consensus, incentives, and timestamps to enable peer-to-peer transactions, coordination, and cooperation based on decentralized credit without third-party trust institutions. Blockchain has the advantages of decentralization, transparency, and tamper resistance, providing opportunities to solve many problems in centralized institutions, and is therefore widely used in digital currency, healthcare, the Internet of Things, and other fields.

[0003] However, with the continuous development of blockchain technology, blockchain storage abuse problems have also emerged due to its tamper resistance. In this case, chain participants may inadvertently facilitate the spread of inappropriate content because they may not be able to identify illegal or inappropriate information, and users may be reluctant to participate and download the chain to avoid being sued for holding such information, thereby hindering the growth and application of blockchain. In addition, its tamper resistance also violates some data regulations, such as the General Data Protection Regulation and the Right to be Forgotten, which provide that anyone has the right to delete personal private information. To alleviate the above problems, the concept of editable blockchain is proposed and applied in the fields of the Internet of Things, healthcare, and housing rental.

[0004] Existing chameleon hash-based editable blockchain schemes mostly specify some modifiers to achieve fine-grained transaction modification, as long as these modifiers meet specific identity or modifier attribute (or access structure) requirements. Unfortunately, there may be malicious modifiers among them, leading to malicious modification events, i.e., modifying good content into bad content, disrupting the blockchain environment. To address the above problems, some modification permission control methods, such as trapdoor periodic expiration and modification limit, and some modification accountability methods, such as attribute revocability and traceability, have received attention. However, these methods only work when or after modification events occur and cannot predict and prevent malicious events before they occur. Early assessment, filtering, and limiting of malicious modifiers is a feasible solution to reduce the risk of potential malicious modifiers making malicious modifications to some extent.

[0005] Therefore, the current blockchain rewriting method has low security. SUMMARY

[0006] The embodiment of the present application provides a dynamic trust-based blockchain rewriting method supporting update traceability, and can solve the problem of low security of the current blockchain rewriting method.

[0007] In a first aspect, the embodiment of the present application provides a dynamic trust-based blockchain rewriting method supporting update traceability, which is applied to an editable blockchain system, the editable blockchain system comprises a plurality of user nodes and an editable global ledger, the user nodes comprise committee members, and the method comprises the following steps:

[0008] The modifier broadcasts a modification suggestion to other committee members in the rth round, wherein the modification suggestion comprises original information to be modified, modified information, a signature of the modifier, a modification reason, and a trust value of the modifier at the current time;

[0009] The modifier is one of the committee members in the rth round, the committee members in the rth round are determined based on trust values of each user node in the editable blockchain at the rth time, the rth time is obtained through election among all user nodes, the rth time is earlier than the current time, the election at the rth time is the last election before the current time, and the trust value of the user node at the rth time is determined according to transaction behaviors, consensus behaviors and modification behaviors of the user node before the rth time;

[0010] The other committee members verify whether the signature of the modifier is correct, whether the modification reason is reasonable, and whether the trust value of the modifier at the current time is greater than or equal to a trust value threshold set by an original user, wherein the original user is a user node uploading original information;

[0011] If the signature of the modifier is correct, the modification reason is reasonable, and the trust value of the modifier at the rth time is greater than or equal to the trust value threshold of the original user, the other committee members accept the modification of the original information by the modifier and replace the original information with the modified information in the editable global ledger, and save a modified signature and a modified random number generated in the modification.

[0012] In a second aspect, the embodiment of the present application provides an editable blockchain system, which comprises a plurality of user nodes and an editable global ledger, the user nodes comprise committee members, and the committee members comprise a modifier and other committee members.

[0013] The modifier is configured to broadcast a modification suggestion to other committee members in the rth round, wherein the modification suggestion comprises original information to be modified, modified information, a signature of the modifier, a modification reason, and a trust value of the modifier at the current time;

[0014] Wherein, the modifier is one of the rth round committee members, the rth round committee members are based on the trust value of each user node at the rth moment in the editable blockchain, the rth moment is obtained by election among all user nodes, the rth moment is earlier than the current moment, the election at the rth moment is the last election before the current moment, and the trust value of the user node at the rth moment is determined according to the transaction behavior, consensus behavior and modification behavior of the user node before the rth moment;

[0015] The other committee members are used to verify whether the signature of the modifier is correct, whether the modification reason is reasonable, and whether the trust value of the modifier at the rth moment is greater than or equal to the trust value threshold set by the original user, wherein the original user is the user node uploading the original message;

[0016] If the signature of the modifier is correct, the modification reason is reasonable, and the trust value of the modifier at the current moment is greater than or equal to the trust value of the original user node, the other committee members are also used to accept the modification of the original information by the modifier and replace the original information with the modified information on the editable global ledger, and save the modified signature and modified random number generated by the modification.

[0017] Compared with the prior art, the beneficial effects of the embodiment of the present application are that: according to the blockchain rewriting method provided by the present application, the trust value of each node is determined according to the historical transaction, consensus and modification behavior of each node, and the committee members are elected according to the trust value of each node, so that the committee members perform the modification behavior; compared with the method of selecting the modifier only by user attributes, the credit value is used to represent the credibility of the user and to select the modifier, which can prevent the user with malicious behavior from modifying the information on the blockchain multiple times, reduce the occurrence of malicious events, and improve the security performance of the blockchain. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A structure schematic diagram of an editable blockchain system provided by the embodiment of the present application;

[0019] Figure 2 An implementation flowchart of a dynamic trust-based blockchain rewriting method supporting update traceability provided by the embodiment of the present application;

[0020] Figure 3 An implementation flowchart of a committee member election method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to better illustrate the dynamic trust-based blockchain rewriting method supporting update traceability provided by the present application, some existing concepts are described before the embodiments are listed:

[0022] Chameleon Hash Algorithm

[0023] The chameleon hash algorithm enables anyone to perform a chameleon hash on a given trapdoor key tk, and the user who possesses the hash key can generally find a hash collision such that Ch Hash(m) = Ch Hash(m’); where Ch Hash(·) represents the chameleon hash, m is the original information, and m’ is the modified information.

[0024] The chameleon hash algorithm can include:

[0025] CH. Setup(1 λ )→ pp: The input is a security parameter is an integer set, and the output is the public parameter pp.

[0026] CH. KeyGen(pp)→(tk, hk): The input is the common parameter pp, and the output is a trapdoor hash key pair (tk, hk), where tk is a trapdoor key and hk is a hash key.

[0027] CH. Hash(hk, m)→(h, r): Generate a message hash value h and an information random number r according to the trapdoor key hk and the original message m∈M, where M is the message space.

[0028] CH. Verify(hk, m, h, r)→b: Verify whether (h, r) is valid by inputting (hk, m, h, r). If the output is 1, the verification is passed, otherwise the verification fails.

[0029] CH. Adapt(tk, m, m’, h, r)→r’: Calculate a collision (m’, r’) about (m, r) through (tk, m, h, r) and the modified message m’∈M, and output the modified random number r’. In addition, the security requirements of the chameleon hash include: correctness, non-repudiation and collision resistance.

[0030] The purpose of using the chameleon hash is to ensure that the modified block hash value remains unchanged in the editable blockchain system.

[0031] Dynamic proactive secret sharing algorithm

[0032] The dynamic proactive secret sharing algorithm can share a trapdoor key among members of a committee consisting of n0 users, but the value of the trapdoor key will not change with the adjustment of the committee, and can be recovered by any t or more members in the committee; where t is the recovery threshold. The members, size and recovery threshold of the committee can be adjusted over time.

[0033] The dynamic proactive secret sharing algorithm can include:

[0034] The protocol is used to share a secret s among n0 members in the original committee C. On input n0, s, t and another security parameter k, and output a tuple containing each member P i 's secret share and correctness proof <s i , π i >.

[0035] The protocol is used to convert secret shares between the old and new committees (i.e. C e and C e+1 ), and update them. On input a tuple {<s i , π i >} maintained by each old member P i e , and output a new tuple {<s j ', π j '>} for each new member P .

[0036] DPSS.Recon({<s i , π i > i∈I})→v The protocol is used to reconstruct s in the new committee. On input at least t+1 valid tuples {<s i , π i > i∈I,|I|>t}, and output the reconstructed secret v, where I is the index set.

[0037] The application will be further described below in conjunction with specific embodiments, but the embodiments of the application are not limited thereto.

[0038] Figure 1 Fig. 1 shows a structure schematic diagram of an editable blockchain system provided by an embodiment of the application.

[0039] As an example but not limitation, the editable blockchain system can include a plurality of nodes 1 and an editable global ledger 2. The nodes 1 can be divided into users 11 and blockchain administrators 12. A committee can be elected from the users 11, and the committee members 111 can modify information on the editable global ledger 2. The committee member 111 performing the modification is a modifier 1111, and the remaining committee members are other committee members 1112. In one example, the modifier 1111 can be used to broadcast a modification suggestion to the other committee members 1112 in the rth round, and then the other committee members 1112 verify whether the modifier's signature is correct, whether the modification reason is reasonable, and whether the trust value of the modifier at the current time is greater than or equal to the trust value threshold set by the original user. If all three conditions are met, the other committee members 1112 accept the modification of the original information by the modifier and replace the original information with the modified information on the editable global ledger 2 to save the modified signature and the modified random number.

[0040] For example, the modifier is one of the committee members in the rth round, the committee members in the rth round are based on the trust value of each user node in the editable blockchain at the rth time, the rth time is obtained by election among all user nodes, the rth time is earlier than the current time, the election at the rth time is the last election before the current time, and the trust value of the user node at the rth time is determined according to the transaction behavior, consensus behavior and modification behavior of the user node before the rth time.

[0041] For example, the original user is a user node that uploads an original message.

[0042] Optionally, each user node can perform an editable transaction or a normal transaction. When performing a normal transaction, the user node can generate an information signature and an information random number through a public key and a private key according to some conventional hash encryption method.

[0043] In the editable blockchain system provided by the present application, the trust value of each node is determined according to the historical transaction, consensus and modification behavior of each node, and the committee members are elected according to the trust value of each node, so that the committee members perform the modification behavior. Compared with screening the modifier only by user attributes, the present application represents the credibility of the user by credit value and screens the modifier, which can prevent users with malicious behavior from modifying information on the blockchain multiple times and improve the security performance of the blockchain.

[0044] Figure 2 An implementation flowchart of a dynamic trust-based blockchain rewriting method supporting update traceability provided by an embodiment of the present application is shown. As an example but not limitation, the method 200 can be applied to the editable blockchain system described above. The method 200 can include steps S201-S209, which are described below.

[0045] S201, the blockchain administrator performs system initialization.

[0046] In a possible implementation, the blockchain administrator can run a setup algorithm: DTCH.Setup(1 λ )→(pp), where λ is a security parameter. Select a prime number e, and generate the public parameters pp DS for constructing a digital signature = DS.Setup(1 λ ) = (G, g); where G is an elliptic curve group, g is a generator of the group G, DS represents an elliptic curve digital signature algorithm, DS.Setup(1 λ ) represents the setup part in the algorithm, and pp DS is the implicit input of (G, g). Then organize an initial committee C 0 , which includes n0 reliable user nodes (i.e., committee members) in the committee C 0 ; at the same time, set a lower limit T l for the trust value threshold, so that the trust value threshold set by each user must be greater than T l . Finally, output the parameter pp = (e, G, g, C 0 , T l ).

[0047] In an example, while the editable blockchain is running according to the method 200, it also performs an election between user nodes based on trust values every first preset time value according to the following committee member election method 300, and elects n0 user nodes with higher trust values as committee members to dynamically update the committee.

[0048] Optionally, the committee members can also regularly check whether the user nodes in the editable blockchain system and their various behaviors are normal, to prevent users with ulterior motives from intentionally enhancing their trust values through a large number of frequent behaviors.

[0049] S202, the blockchain administrator generates a trapdoor hash key pair based on the output parameter.

[0050] In a possible implementation, the trapdoor hash key pair can be generated based on the output parameter according to the chameleon hash algorithm.

[0051] For example, a key generation algorithm DTCH.KeyGen(pp)→(tk,hk) can be run to generate a trapdoor key tk and a hash key sk.

[0052] Specifically, a key generator RSAKGen(1 λ ) in an asymmetric encryption algorithm can be run to generate two different large prime numbers p and q. Then calculate n = pq, obtain a parameter d; wherein then select an anti-collision hash function is a group consisting of all invertible elements of the modulo n congruence class, for any n≥1, the set of integers modulo n forms a finite additive group containing n elements. Meanwhile, a second preset time value is set According to the parameter d, a trapdoor key tk←d is generated. According to the second preset time value and the hash function H n , Δt), a hash key hk←(n, H n , Δt) is generated.

[0053] In an example, the dynamic proactive secret sharing algorithm can be based on: Sharing the trapdoor key among the initial committee members.

[0054] Optionally, the recovery threshold t0 of the trapdoor key can satisfy: t0<n0 / 2.

[0055] S203, the user node generates the information signature of the original information according to the private key in the signature key pair, the preset time, the original information, the information random number, and the trust value threshold.

[0056] In an example, the user node can run a hash algorithm: DTCH.Hash(hk, Tt, m, t)→(h, r, σ), to generate the information random number, the information hash value, and the information signature of the original information according to the time trust value threshold Tt set by the user, the preset time t, the hash key hk, and the original message m.

[0057] Specifically, the information random number r can be selected as: and the information hash value h is calculated according to the information random number: h=H n (m) t r e mod n. Then, based on the key generation part in the elliptic curve digital signature algorithm: (sk, pk)←DS.KeyGen(pp DS ), the public key pk and the private key sk in the signature key pair are generated. Then, based on the signature part in the algorithm: σ=(y, s)←DS.Sign(sk, (Tt, m, r, t)), the information signature is generated according to the private key in the signature key pair, the preset time, the original information, the information random number, and the trust value threshold. Wherein, y=g w mod P, s=w -1 (H d (Tt, m, r, t)+y·sk), w is a random number selected from the set , and the set is a non-zero element, is a domain, H d is a hash function used for generating digital signature.

[0058] Optionally, the trust value threshold can be less than each committee member's trust value, and greater than the lower limit T l , that is, T l ≤ Tt≤ Tr(C k ) and k≤ n0, C k is the kth committee member; to avoid the case that a malicious user sets a higher trust value threshold and then uploads malicious information, but no modifier who meets the conditions can modify the malicious information, and improve the security performance of the blockchain.

[0059] S204, the user node broadcasts the message parameters of the current message upload to other user nodes.

[0060] For example, the message parameters can include the public key in the signature key pair, the preset time, the information random number, the original information, the trust value advance, the information hash value and the information signature.

[0061] Correspondingly, other user nodes receive the message parameters of the current message upload.

[0062] S205, the user node receiving the message parameters verifies whether the message parameters are valid.

[0063] In one possible implementation, the user node receiving the message parameters can run the verification algorithm: DTCH.Verify(hk,Tt,m,t,r,h,σ)→{0,1} to verify whether the message parameters are valid.

[0064] Specifically, the information random number can be verified first to see whether it satisfies: If it satisfies, it continues, and if it does not satisfy, it outputs 0 and stops. Then verify where h'=H n (m) t r e mod n; and based on the verification part in the elliptic curve digital signature algorithm: verify the remaining parameters. If both equations are true, return 1 to save the message parameters on the editable global ledger, and / or broadcast the message parameters to other user nodes that have not received the message parameters; if either is not true, return 0 to stop the current message upload.

[0065] S206, the modifier broadcasts the modification suggestion to other committee members in the rth round.

[0066] In an example, the modification suggestion ModTx may include: the modifier's information ModifierID, the located block number BlockNum, the transaction number TxNum, the original information m, the modified information m', the modifier's trust value Tc at the rth moment, the modification reason Reason, the modifier's signature Sign and the suggested state State.

[0067] For example, the suggestion status may include: active, accepted, and rejected. The initial status of the suggestion status in the modification suggestion sent by the editor may be active.

[0068] Accordingly, other committee members in round r receive the modification suggestions.

[0069] In step S207, other committee members in round r verify whether the signature of the modifier is correct, whether the reason for the modification is reasonable, and whether the trust value of the modifier at the current moment is greater than the trust value threshold set by the original user.

[0070] For example, other committee members in round r can verify the correctness, rationality, and feasibility of the modification by verifying whether the modified signature is correct, whether the reason for the modification is reasonable, and whether the trust value of the modifier at the current moment is greater than the trust value threshold set by the original user.

[0071] In one example, if all three conditions above are met, then in round r, other committee members can modify the proposed status to accepted and then collectively recover the trapdoor key of the modifier.

[0072] In another example, if any of the conditions is not met, the proposed status may be modified to rejected and the modification may be stopped.

[0073] In step S208, the modifier recovers the trapdoor key from the committee members based on the dynamic active secret sharing algorithm.

[0074] In one example, committee members can use the key recovery part of the dynamic active secret sharing algorithm: tk←DPSS.Recon({tk i} t+1 ), reconstruct the trapdoor key from the r-th round committee members; and send it to the modifier through a secure P2P channel.

[0075] Optionally, committee members can first The message parameters related to the original information are verified again. If the verification result is 0, the modification is stopped. Otherwise, the modification is performed when the trust value of the modifier at the rth moment is greater than the trust value threshold Tt set by the original user.

[0076] S209, the modifier generates a modified random number according to the trapdoor key and generates a modified signature according to the private key of the new signature key pair.

[0077] In one example, the modifier can calculate the modified random number r' = (h / H n (m') t ) d modn after receiving the trapdoor key based on the chameleon hash algorithm. Then generate a new signature key pair based on the key generation part in the elliptic curve digital signature algorithm: (sk', pk') ← DS.KeyGen(PP DS ) to obtain a new private key sk' and a new public key pk'. And generate a modified signature according to the private key of the new signature key pair based on the signature part in the elliptic curve digital signature algorithm: σ' = (y', s') ← DS.Sign(sk', (Tt, m', r', t)),.

[0078] Similarly, the modifier can run the verification algorithm: DTCH.Verify(hk, Tt, m', t, r', h, σ') to check whether the modified random number and the modified signature are valid.

[0079] Optionally, the method 200 can further include step S208; every second preset time value, the modifier in the editable blockchain system can execute step S208 once.

[0080] S210, the modifier updates the information random number, the information signature, and / or the modified random number, the modified signature.

[0081] In one possible implementation, similar to the adaptation algorithm: DTCH.Adapt(C r , tk, m, t, r, h, m', Tc, Tt) → (r', σ') including step S208, step S209; the update algorithm first verifies whether the information random number, the information signature, and / or the modified random number, the modified signature at the current time are valid through the verification algorithm If valid, continue updating so that the verification only passes within a fixed second preset time value; if invalid, stop updating. Then reconstruct the trapdoor key from the committee C j in the jth round based on the algorithm: tk ← DPSS.Recon({tk j} t+1 ) in the elliptic curve digital signature algorithm. Calculate the updated random number r'' = r / (H n (m) Δt ) d modn after the modifier receives the trapdoor key; generate a new signature key pair based on the algorithm: (sk'', pk'') ← DS.KeyGen(PP DS), a new signature key pair is constructed; and an updated random number and signature are generated according to an algorithm: σ" = (y", s") <- DS.Sign(sk", (Tt, m, r", t + Δt)). Finally, a verification algorithm: DTCH.Verify(hk, Tt, m, t + Δt, r", h, σ") is run to check whether the updated random number and signature are valid.

[0082] According to the blockchain rewriting method provided by the application, the trust value of each node is determined according to the historical transaction, consensus and modification behavior of each node, and the committee members are elected according to the trust value of each node, so that the committee members perform the modification behavior. Compared with screening the modifier only by user attributes, the application can prevent users with malicious behavior from modifying the information on the blockchain multiple times by representing the credibility of users by credit values and screening the modifier, thereby improving the security performance of the blockchain. Further, when the editable transaction is performed, the original user sets the trust value threshold to ensure that only the modifier meeting the trust value threshold can modify; the corresponding digital signature is generated in each transaction and modification to enable the system to trace the identity of the user or the modifier of the transaction through the digital signature; and the security performance of the system can be further improved.

[0083] Figure 3 An implementation flowchart of a committee member election method provided by an embodiment of the application is shown. As an example but not limitation, the method 300 can be applied to the editable blockchain system described above, and the method 300 can include steps S301-S306, which are described below.

[0084] S301, determining the transaction trust value of the user node at the rth moment according to the transaction behavior of the user node before the rth moment.

[0085] In one example, the transaction trust value of the user node at the rth moment can satisfy the following formula:

[0086]

[0087] wherein GT(u) is the transaction trust value of the uth user node at the rth moment, T u is the number of transactions of the uth user node between the r-1th moment and the rth moment, ρ(T u is the activity value of the transaction, Δt i is the time interval between the ith transaction and the i-1th transaction of the uth user node, is a trust decay degree of the ith transaction relative to the rth moment, indicating that the recent performance of the user node is more valued; f(i) is a transaction influence factor of the ith transaction, used to identify the importance of the transaction, and the specific value can be set according to the requirements and standards of different actual scenes; Tr(j) is a trust value of the uth user node fed back from the jth user node, S i is an evaluation feedback of the ith transaction, and DT0 is a default trust value when no transaction is performed.

[0088] wherein:

[0089] For example, the r-1th moment is the moment when the user node performs the r-1th election.

[0090] Optionally, the user can elect a committee member based on the trust value of each user every first preset time value.

[0091] S302, determining a consensus trust value of the user node at the rth moment according to the consensus behavior of the user node before the rth moment.

[0092] In one example, the formula trust value of the user node at the rth moment can satisfy the following formula:

[0093]

[0094] wherein CM(u) is a consensus trust value of the uth user node at the rth moment, C u is the number of times of consensus of the uth user node between the r-1th moment and the rth moment, p(C u ) is an activity value of consensus, and the calculation method is the same as that of the activity value of transaction; B i′ is a behavior value of the uth user node when performing the ith consensus, and At i′ is a time interval between the ith consensus and the ith-1 consensus, is a trust decay degree of the ith consensus relative to the rth moment.

[0095] wherein:

[0096]

[0097] wherein the parameters ψ and φ can be defined as 0≤ψ<0.03 and 0≤φ<1 respectively.

[0098] For example, malicious behavior can include malicious feedback, transaction fraud, malicious consensus, malicious modification of on-chain data, etc.

[0099] S303, determining a modification trust value of the user node at the rth moment according to the modification behavior of the user node before the rth moment.

[0100] In one example, if the user node completes M u times of modification within the first preset time value, after the i" modification, the user node can accept the evaluation feedback from other users about the i" modification. If the number of feedback from other users exceeds a certain percentage of the total number of user nodes, the user node can calculate the evaluation feedback comprehensive value algorithm where View i,1 represents the evaluation feedback received from user l, and N is the number of received feedback. Therefore, the modification trust value of the user node at time r can satisfy the following formula:

[0101]

[0102] where MT(u) is the modification trust value of the u-th user node at time r, M u is the number of modifications performed by the u-th user node between time r-1 and time r, p(M u ) is the modification activity value, V(i") is the evaluation feedback comprehensive value received by the u-th user node after the i" modification from other user nodes about the i" modification, N is the total number of evaluation feedback received by the u-th user node about the i" modification, At i″ is the time interval between the i" modification and the i"-1 modification, is the trust decay degree corresponding to the i" modification at time r, and f(i") is the influence factor of the i" modification.

[0103] For example, after the user performs each transaction, modification, or formula behavior, the user node can update its trust value for the corresponding behavior by using the above formula. Once the user node performs malicious behavior, the user node can be punished, otherwise a certain degree of reward can be implemented.

[0104] S304, according to the transaction trust value of the user node at time r, the consensus trust value of the user node at time r, and the modification trust value of the user node at time r, determine the comprehensive trust value of the user node at time r.

[0105] In one example, the comprehensive trust value of the user node at time r can be the sum of the product of the transaction trust value of the user node at time r and the transaction weight, the product of the consensus trust value of the user node at time r and the consensus weight, and the product of the modification trust value of the user node at time r and the modification weight. That is, the comprehensive trust value of the user node at time r can satisfy the following formula:

[0106] S c = a · GT(u) + β · CM(u) + γ · MT(u)

[0107] wherein, S c is the comprehensive trust value of the user node at the rth moment, and α, β, and γ are respectively the transaction weight, the consensus weight, and the modification weight.

[0108] S305, determining the trust value of the user node at the rth moment according to the comprehensive trust value of the user node at the rth moment and the trust value of the user node at the (r-1)th moment.

[0109] In one example, the trust value of the user at the rth moment can satisfy the following formula:

[0110] Tr(u) r ← x·min(T r-1 ,S c ) + y·max(T r-1 ,S c ) + δ

[0111] wherein, Tr(u) r is the trust value of the user node at the rth moment, S c is the comprehensive trust value of the user node at the rth moment, x and y are two weight values, x+y=1, and x>y.

[0112] wherein:

[0113]

[0114] wherein, η>1, η is an adjustment parameter, representing the reward for the normal behavior of the user node or the punishment for the malicious behavior of the user node. Obviously, the reward is significantly lower than the punishment for all users, so as to encourage the user to make normal behavior. In addition, compared with the user with a low trust value, the user with a high trust value obtains less reward for normal behavior and more punishment for malicious behavior.

[0115] S306, performing the rth round of election among all user nodes based on the credit value of the user node at the rth moment, and selecting the rth round of committee members.

[0116] For example, the first n0 user nodes with higher credit values at the rth moment can be determined as the rth round of committee members.

[0117] According to the committee member election method provided by the application, the trust value of the user can be updated according to the historical behavior of the user, and the dynamically changing trust value can more reliably filter and limit malicious users.

[0118] In the description of the application, the terms "first", "second", "third", etc. are used only to describe different embodiments and do not imply or suggest relative importance or a specific number of the technical features indicated. Thus, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0119] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the present application.

[0120] Although the present application is described herein in conjunction with various embodiments, those skilled in the art, with the benefit of the drawings, the disclosure, and the appended claims, can understand and appreciate other variations of the disclosed embodiments in implementing the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can implement several of the functions recited in the claims. Measures recited in mutually different dependent claims do not necessarily have to be mutually exclusive.

[0121] The above is a further detailed description of the present application in conjunction with specific preferred embodiments, and the specific implementation of the present application should not be limited to these descriptions. Modifications made by those skilled in the art without departing from the concept of the present application should be considered within the scope of protection of the present application.

Claims

1. A blockchain rewriting method based on dynamic trust that supports update traceability, characterized in that: The method is applied to an editable blockchain system, the editable blockchain system including multiple user nodes and an editable global ledger, the user nodes including committee members, and the method comprising: The editor to r Other committee members in the round broadcast modification suggestions, where the modification suggestions include the original information to be modified, the modified information, the signature of the modifier, the reason for the modification, and the trust value of the modifier at the current moment; Among them, the modifier is r One of the members of the Round Committee, r The round committee members are based on the first r Trust value at the moment, r The first r The time is earlier than the current time, in the r The election conducted at this moment is the last election conducted before the current moment. r The trust value at the moment is based on the user node at r Determined by the transaction behavior, consensus behavior and modification behavior before the moment; The other committee members verify whether the signature of the modifier is correct, whether the reason for the modification is reasonable, and whether the modifier's current trust value is greater than or equal to the trust value threshold set by the original user, where the original user is the user node that uploaded the original message; If the signature of the modifier is correct, the reason for the modification is reasonable and the modifier r If the trust value of the modifier is greater than or equal to the trust value threshold of the original user, the other committee members accept the modification of the original information by the modifier and replace the original information with the modified information on the editable global ledger, and save the modified signature and modified random number generated by this modification; Wherein, the modifier r Before broadcasting the proposed changes to other committee members, the method further includes: According to the user node r The transaction trust value at the moment, the user node r The consensus trust value at the moment and the user node r The modified trust value of the user node at the moment r The comprehensive trust value at the moment; According to the user node r The comprehensive trust value at the moment, the user node r -1 moment trust value, determine the user node r The trust value at the moment, where r -1 moment earlier than r moment, the r -1 time is when the user node performs the r -1 round of elections, the r The moment and the r The time difference at time -1 is equal to a first preset time value, and every first preset time value, all user nodes elect committee members once; The first r The front with the largest trust value at any time The user node is determined as the r Members of the Rotating Committee, is the total number of committee members; Wherein, the user node r The trust value at the moment satisfies the following formula: For the user node r The trust value of the moment, For the user node r -1 trust value at the moment, For the user node r The comprehensive trust value at the moment, 、 are two weight values, ; in: , It is an adjustment parameter, which represents the reward for normal behavior of user nodes or the punishment for malicious behavior of user nodes.

2. The method according to claim 1, characterized in that The user node r The comprehensive trust value of the user node at the moment r The product of the transaction trust value and transaction weight at the moment, the user node r The product of the consensus trust value and the consensus weight at the moment, the user node r The sum of the product of the modified trust value and the modified weight at the moment.

3. The method according to claim 1 or 2, characterized in that The user node r The transaction trust value at the moment satisfies the following formula: in, For the u User node r The transaction trust value at each moment, For the said u The user node in the r -1 moment and the r The number of transactions during a given time period, is the activity value of the transaction, For the said u User nodes are performing i The transaction and i -1 time interval between transactions, For the said i The transaction is relative to the r Trust decay at any moment, For the said i The transaction impact factor of the transaction, For the j The feedback from the user node u The trust value of the user node, For the said i Transaction feedback, The default trust value.

4. The method according to claim 1 or 2, characterized in that The user node r The consensus trust value at the moment satisfies the following formula: in, For the u User node r The consensus trust value at all times, For the said u The user node in the r -1 moment and the r The number of consensuses during a time period, is the consensus activity value, For the said u User nodes are performing The behavior value at the time of the second consensus, For the said The second consensus and the -The time interval between 1 consensus, For the said The second consensus is relative to the r Trust decay at any moment, The default trust value.

5. The method according to claim 1 or 2, characterized in that: The user node r The modified trust value at the moment satisfies the following formula: in, For the u User node r Modify the trust value at any time. The said u The user node in the r -1 moment and the r The number of modifications made during a time period, is the modified activity value, For the said u User nodes perform the After the modification, other user nodes receive information about the The comprehensive value of the evaluation feedback of the modification, For the said u The user node receives the The total number of modified review feedback, For the said The first revision and -1 time interval between modifications, For the said The second revision is equivalent to r Trust decay at any moment, For the said The impact factor of the revision, The default trust value.

6. The method according to claim 1, characterized in that The trapdoor key in the modified trapdoor hash key pair is based on the dynamic active secret sharing algorithm described in the first r Shared among the members of the wheel committee.

7. The method according to claim 6, characterized in that In the case of the modifier r Before broadcasting the proposed changes to other committee members, the method further includes: The user node generates a signature for the original information based on the private key in the signature key pair, the preset time, the original information, the information random number, and the trust value threshold; The user node broadcasts the message parameters of this message upload to other user nodes, wherein the message parameters include: the public key of the signature key pair, the preset time, the information random number, the original information, the trust value threshold, the information hash value and the information signature; The user node receiving the message parameters verifies whether the message parameters are valid; If the message parameters are all valid, the user node that receives the message parameters saves the message parameters on the editable global ledger, and / or broadcasts the message parameters to user nodes that have not received the message parameters; The modifier uses the dynamic active secret sharing algorithm to r recovering the trapdoor key from the committee members at that moment; Among them, if the signature of the modifier is correct, the reason for the modification is reasonable and the modifier is r If the trust value of the original user is greater than or equal to the trust value threshold of the original user, then before the other committee members accept the modification of the original information by the modifier and replace the original information with the modified information on the editable global ledger, and save the modified signature and modified random number generated by the modification, the method further includes: The modifier generates the modified random number according to the trapdoor key; The modifier generates the modified signature according to the private key in the new signature key pair.

8. The method according to claim 7, characterized in that The modifier updates the information random number, the information signature, and / or the modified random number, the modified signature every second preset time value.

9. An editable blockchain system, characterized in that: The editable blockchain system is used to perform blockchain rewriting according to the method according to any one of claims 1 to 8, wherein the editable blockchain system includes multiple user nodes and an editable global ledger, wherein the user nodes include committee members, and the committee members include modifiers and other committee members; The modifier is used to r Other committee members in the round broadcast modification suggestions, where the modification suggestions include the original information to be modified, the modified information, the signature of the modifier, the reason for the modification, and the trust value of the modifier at the current moment; Among them, the modifier is r One of the members of the Round Committee, r The round committee members are based on the first r Trust value at the moment, r The first r The time is earlier than the current time, in the r The election conducted at this moment is the last election conducted before the current moment. r The trust value at the moment is based on the user node at r Determined by the transaction behavior, consensus behavior and modification behavior before the moment; The other committee members are used to verify whether the signature of the modifier is correct and whether the reason for the modification is reasonable. r Whether the trust value at the moment is greater than or equal to the trust value threshold set by the original user, wherein the original user is the user node that uploaded the original message; If the modifier's signature is correct, the reason for the modification is reasonable, and the modifier's current trust value is greater than or equal to the trust value of the original user node, the other committee members are further configured to accept the modifier's modification of the original information and replace the original information with the modified information on the editable global ledger, and save the modified signature and modified random number generated by this modification.

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