Editable block chain method supporting dynamic trap door

Abstract

The invention discloses an editable block chain method supporting a dynamic trap door. The method comprises the steps of public parameter generation, main trap door key pair generation, user key generation, chameleon hash value generation, collision search, user key and hash verification, trap door abortion and update and trap door update verification. According to the method, the chameleon hash supporting the dynamic trap door is adopted, the dynamic update of the trap door can be realized when the inherent tamper-proof property of the block chain is broken through, only a user with a legal trap door key can change the chained data, and the risk that malicious nodes hold the trap door for a long time is reduced. Related security test results show that the method has advantages in the aspect of security, higher security assurance is realized with relatively low calculation cost, the dynamic timeliness of the trap door private key is improved, and organic fusion of editability and security credibility of the block chain is realized.

Description

Technical Field

[0001] The present invention belongs to the field of blockchain and information security technology, and in particular relates to an editable blockchain method supporting dynamic trapdoors. Background Art

[0002] In 2008, Nakamoto first proposed an electronic payment system based on peer-to-peer (P2P) network and consensus mechanism - Bitcoin. As the core technology of Bitcoin, blockchain has attracted widespread attention from academia, industry and government departments due to its decentralization, openness, transparency and immutability. Among them, immutability means that once data is recorded on the blockchain, it cannot be deleted or modified, which provides a guarantee for the reliability and credibility of blockchain data. However, this permanent storage feature also brings many security risks. Malicious users may upload sensitive or illegal data to the blockchain, seriously affecting the healthy development of the network. Therefore, studying the editable scheme of blockchain data has important theoretical significance and practical application value.

[0003] Chameleon hashing is an important technology in cryptography. It is a one-way hash function with a trapdoor. If the trapdoor is unknown, the chameleon hashing function can resist pre-image attacks and collision attacks. If the trapdoor is known, the collision of any input data can be efficiently constructed. In other words, the input can be modified arbitrarily without affecting the output hash value. Using the chameleon hashing function to construct an editable blockchain solution is a more reliable way with advantages such as low cost and high efficiency. It is also the mainstream way to construct an editable blockchain. However, the existing editable blockchain solutions based on chameleon hashing all have security risks such as trapdoor abuse and trapdoor leakage. Summary of the invention

[0004] To solve the above problems, the present invention proposes an editable blockchain method that supports dynamic trapdoors. While breaking through the inherent immutability of blockchain, the method can realize dynamic update of trapdoors. Even if the key is stolen, the key held by the thief will become invalid after a period of time, thereby reducing the risk of malicious nodes holding trapdoors for a long time. The present invention has advantages in security, achieves higher security guarantees at a lower computational cost, improves the dynamic timeliness of trapdoor private keys, and realizes the organic integration of the editability and security credibility of blockchain.

[0005] The technical solution of the present invention is specifically described as follows.

[0006] The present invention provides an editable blockchain method supporting dynamic trapdoors, comprising the following steps:

[0007] Step 1: The certification authority inputs the selected security parameters and outputs the public parameters;

[0008] Step 2: The authorized institution inputs public parameters, generates the system master trapdoor key and the system master public key, and outputs the Chameleon hash master trapdoor key pair;

[0009] Step 3: The data modifier sends his / her user ID to the authorization agency. The authorization agency inputs the Chameleon Hash master trapdoor key pair, the data modifier's user ID, the expiration date of the user key held by the data modifier, and returns the timestamp function, and outputs the data modifier's identity parameters and user key.

[0010] Step 4: The data modifier inputs the system master public key, data modifier identity parameters, original information string and random number, and outputs the chameleon hash value corresponding to the original message;

[0011] Step 5: The data modifier inputs the system master public key, chameleon hash value, original message string, random number, and new message string, and outputs a new chameleon hash value and a new random number;

[0012] Step 6: The data modifier inputs the system master public key, chameleon hash value, original message string, random number, new message string, new chameleon hash value and new random number, data modifier identity parameter, user key, and verifies the validity of the user key and the correctness of the hash value;

[0013] Step 7: The authorized agency cancels the existing Chameleon Hash master trapdoor key pair (ie, the old trapdoor) and generates a new Chameleon Hash master trapdoor key pair (ie, the new trapdoor). The updated trapdoor satisfies that the new trapdoor value does not depend on the old trapdoor value.

[0014] Step 8: The authority verifies whether the old trapdoor is successfully revoked. If so, it returns a verification success; otherwise, it returns a verification failure.

[0015] Preferably, in step 1, the certification authority inputs the selected security parameter λ; selects a multiplicative cyclic group G and G with an order of q and a generator of g. T , where q represents a large prime number, g represents the generator number of G, and G and G T Represent two multiplicative cyclic groups; define two hash functions H:{0,1} * →G,H1:{0,1} * →Z q , where Z q represents a finite field of order q; e represents a bilinear map e: G×G→G T ; Output common parameter pp is {G,G T ,e,g,H,H1}.

[0016] Preferably, in step 2, the authorized institution inputs the public parameter pp, generates the system master trapdoor key mtk and the system master public key hk, and outputs the chameleon hash master trapdoor key pair (mtk, hk). The system master trapdoor key mtk is kept by the authorized institution, and the system master public key hk is made public. The process of generating the chameleon hash master trapdoor key pair is as follows:

[0017] Select random number Calculate y = g x , run the algorithm to generate the master trapdoor key pair (mtk, hk), let the system master public key hk = y, the master trapdoor key mtk = x. Among them, Represents the set of integers consisting of 1, 2, …, q-1.

[0018] Preferably, step 3 includes the following sub-steps:

[0019] 3.1: The data modifier sends his / her user identity CID to the authorized agency.

[0020] 3.2: The authorized institution inputs the master trapdoor key pair (mtk, hk), the user identity identifier CID, and the user key usage period h of the data modifier. valid , timestamp function ctime(), generates a specific identity h for the data modifier, and outputs the data modifier identity parameter ID PP {CID,h valid ,h} and user key tk, and sent to the data modifier. The calculation process of the specific identity h and user key tk is as follows:

[0021]

[0022] tk=h x ;

[0023] Wherein, CID represents the user identity; valid Indicates the expiration date in seconds; ctime() indicates the timestamp function.

[0024] Preferably, in step 4, the data modifier enters the system master public key hk, the data modifier identity parameter ID PP , the original information string m and the random number r, and output the chameleon hash value CH. Calculate the chameleon hash value CH corresponding to the information m:

[0025]

[0026] Where m∈{0,1} * ; r represents a random number, r = g αx ,

[0027] Preferably, in step 5, the data modifier inputs the system master public key hk, the chameleon hash value CH, the original message string m, the random number r, and the new message string m′, and calculates the chameleon hash value CH′ corresponding to m′:

[0028]

[0029] Where m′∈{0,1} * ; r' represents a new random number, r' = g α′x′ ,

[0030] Preferably, in step 6, the data modifier inputs the system master public key hk, the chameleon hash value CH, the original message string m, the random number r, the new chameleon hash value CH′, the new message string m′ and the new random number r′, and the data modifier identity parameter ID PP , user key tk, verify the validity of the user key and the correctness of the hash value, the specific implementation is as follows:

[0031] Get the data modifier's identity parameter ID PP The user identity identifier CID in and the specific identity identifier h in the user key tk are used to determine whether the user key is within the validity period. If not, Status = Expired is output.

[0032] Get CH and CH′, and determine whether CH=CH′ is true. If so, output Status=Valid; otherwise, output Status=Invalid.

[0033] Preferably, in step 7, the authorization agency abolishes the existing Chameleon Hash master trapdoor key pair (ie, the old trapdoor) and generates a new Chameleon Hash master trapdoor key pair (ie, the new trapdoor), and the updated trapdoor satisfies that the new trapdoor value does not depend on the old trapdoor value. The specific implementation is as follows:

[0034] The authorized institution enters the public parameter pp and selects a random number Calculate y′=g x′ , output a new Chameleon hash master trapdoor key pair (mtk′, hk′), let the system master public key hk′=y′, the master trapdoor key mtk′=x′, and use the master trapdoor key mtk′ to calculate the new user key tk′ corresponding to the user identity CID.

[0035] Preferably, in step 8, the authorization agency verifies the validity of the user key tk, and outputs Status=Success if it is not within the validity period, that is, the old trapdoor cannot generate a valid hash value, verifying that the old trapdoor is successfully revoked, otherwise it outputs Status=Fail.

[0036] As mentioned above, the present invention proposes an editable blockchain method supporting dynamic trapdoors, and the beneficial effects of the method are as follows:

[0037] (1) In the present invention, a chameleon hash function is used, and a trapdoor abolition and update algorithm is added to the function. When the inherent immutability of the blockchain is broken, the dynamic update of the trapdoor can be realized. Even if the key is stolen, the key held by the thief will become invalid after a period of time, thereby reducing the risk of malicious nodes holding the trapdoor for a long time, solving the security risks of trapdoor abuse and trapdoor leakage, and having higher security;

[0038] (2) In the present invention, an identity-based user key generation algorithm is adopted. After identifying the user identity, the corresponding user key is generated and the validity period is set. The authorization is effectively revoked with controllable randomness, so that only users with legitimate trapdoor keys can change the data on the chain, which has the effect of dynamic permission management;

[0039] (3) The relevant security test results show that the method in the present invention has advantages in terms of security, and has good operating efficiency in each stage, achieving higher security guarantees at a lower computational cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a system model diagram of the present invention.

[0042] Figure 2 is a flow chart of the method of the present invention.

[0043] Figure 3 It is a computational cost diagram comparing the multiple executions of key algorithms by the method of the present invention with other different methods. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The present invention provides an editable blockchain method supporting dynamic trapdoors. The method uses controllable randomness, that is, the trapdoor key will be automatically updated after a certain period of time or after being used once. In this case, the authorized node cannot successfully find a hash collision using the old key, thereby effectively revoking its authorization, so that only users with legal trapdoor keys can change the on-chain data, so as to solve the security risks of trapdoor abuse and trapdoor leakage in the existing editable blockchain solution, have dynamic permission management and lightweight effects, and realize the organic integration of blockchain editability and security credibility.

[0046] like Figure 1 As shown, the present invention mainly involves four entities: a certification body, an authorization body, a data user and a data modifier.

[0047] Certification Authority: The certification authority is responsible for initializing the entire system.

[0048] Authorization agency: After verifying the identity of the data modifier, the authorization agency is responsible for distributing user keys (from the trapdoor) to the data modifier, ensuring that blockchain data can only be edited if the editing policy is met.

[0049] Data user: The data user is responsible for packaging the original data into a transaction order and broadcasting it to the blockchain network, and broadcasting data modification requests when there is a need to modify the relevant data.

[0050] Data modifier: When the attribute set owned by the data modifier meets the corresponding editing strategy, the data on the blockchain can be edited.

[0051] The workflow of the present invention is as follows: the certification body first initializes the entire system and broadcasts the generated public parameters to other entities in the system, while the data modifier completes the generation of its own user key; then, the data user broadcasts the transaction to the blockchain network and appends the transaction to the blockchain; if illegal data is found in a transaction on the blockchain, the data user can initiate an editing request to the data modifier; after verifying the legitimacy of the editing request, the data modifier updates the corresponding transaction content on the blockchain.

[0052] like Figure 2 As shown, the present embodiment provides an editable blockchain method supporting dynamic trapdoors, comprising the following steps:

[0053] Step 1: The certification authority inputs the selected security parameters and outputs the public parameters.

[0054] In one embodiment, the implementation of step 1 includes the following:

[0055] The certification authority inputs the selected security parameter λ; selects the multiplicative cyclic group G and G with order q and generator g. T, where q represents a large prime number, g represents the generator number of G, and G and G T Represent two multiplicative cyclic groups; define two hash functions H:{0,1} * →G,H1:{0,1} * →Z q , where Z q represents a finite field of order q; e represents a bilinear map e: G×G→G T ; Output common parameter pp is {G,G T ,e,g,H,H1}.

[0056] Step 2: The authorized institution inputs public parameters, generates the system master trapdoor key and the system master public key, and outputs the Chameleon hash master trapdoor key pair.

[0057] In one embodiment, the implementation of step 2 includes the following:

[0058] The authorized institution inputs the public parameter pp, generates the system master trapdoor key mtk and the system master public key hk, and outputs the Chameleon Hash master trapdoor key pair (mtk, hk). The system master trapdoor key mtk is kept by the authorized institution, and the system master public key hk is made public. The process of generating the Chameleon Hash master trapdoor key pair is as follows:

[0059] Select random number Calculate y = g x , run the algorithm to generate the master trapdoor key pair (mtk, hk), let the system master public key hk = y, the master trapdoor key mtk = x. Among them, Represents the set of integers consisting of 1, 2, …, q-1.

[0060] Step 3: The data modifier sends his or her identity to the authorization agency. The authorization agency inputs the Chameleon Hash master trapdoor key pair, the data modifier's user identity, the data modifier's user key usage period, returns a timestamp function, and outputs the data modifier's identity parameters and user key.

[0061] In one embodiment, the implementation of step 3 includes the following:

[0062] The data modifier sends his / her user identity identifier CID to the authorization agency and requests the generation of the modifier identity parameter ID PP The authorization agency inputs the master trapdoor key pair (mtk, hk), the user identity CID, and the user key usage period h of the data modifier. valid , timestamp function ctime(), generates a specific identity h for the data modifier, and outputs the data modifier identity parameter ID PP {CID,h valid,h} and user key tk. The calculation process is as follows:

[0063]

[0064] tk=h x ;

[0065] Wherein, CID represents the user identity; valid Indicates the validity period in seconds; ctime() indicates the timestamp function. Here, after identifying the user's identity, the corresponding user key is generated and the validity period is set. The controllable randomness is used to effectively revoke the authorization, so that only users with legal trapdoor keys can change the on-chain data, which has the effect of dynamic permission management.

[0066] Step 4: The data modifier inputs the system master public key, data modifier identity parameters, original information string and random number, and outputs the chameleon hash value corresponding to the original message.

[0067] In one embodiment, the implementation of step 4 includes the following:

[0068] The data modifier enters the system master public key hk and the data modifier identity parameter ID PP , the original information string m and the random number r, and output the hash value CH. Calculate the chameleon hash value CH corresponding to the information m:

[0069]

[0070] Where m∈{0,1} * ; r represents a random number, r = g αx ,

[0071] Step 5: The data modifier inputs the system master public key, chameleon hash value, original message string, random number, and new message string, and outputs a new chameleon hash value and a new random number.

[0072] In one embodiment, the implementation of step 5 includes the following:

[0073] The data modifier inputs the system master public key hk, chameleon hash value CH, original message string m, random number r, new message string m′, and calculates the chameleon hash value CH′ corresponding to m′:

[0074]

[0075] Where m′∈{0,1} * ; r' represents a new random number, r' = g α′x′ ,

[0076] Step 6: The data modifier inputs the system master public key, Chameleon hash value, original message string, random number, new message string, new hash value and new random number, data modifier identity parameters, and user key to verify the validity of the user key and the correctness of the hash value.

[0077] In one embodiment, the implementation of step 6 includes the following:

[0078] The data modifier inputs the system master public key hk, chameleon hash value CH, original message string m, random number r, new hash value CH′, new message string m′ and new random number r′, and data modifier identity parameter ID PP , user key tk, verify the validity of the user key and the correctness of the hash value, the specific implementation is as follows:

[0079] Get the data modifier's identity parameter ID PP The user identity identifier CID in and the specific identity identifier h in the user key tk are used to determine whether the user key is within the validity period. If not, Status = Expired is output.

[0080] Get CH and CH′, and determine whether CH=CH′ is true. If so, output Status=Valid; otherwise, output Status=Invalid.

[0081] Step 7: The authorized agency cancels the existing Chameleon Hash master trapdoor key pair (ie, the old trapdoor) and generates a new Chameleon Hash master trapdoor key pair (ie, the new trapdoor). The updated trapdoor satisfies that the new trapdoor value does not depend on the old trapdoor value.

[0082] In one embodiment, the implementation of step 7 includes the following:

[0083] The authorized institution abolishes the existing Chameleon Hash master trapdoor key pair (i.e., the old trapdoor) and generates a new Chameleon Hash master trapdoor key pair (i.e., the new trapdoor). The updated trapdoor satisfies that the new trapdoor value does not depend on the old trapdoor value. The specific implementation is as follows:

[0084] The authorized institution enters the public parameter pp and selects a random number Calculate y′=g x′(mod q), output a new chameleon hash master trapdoor key pair (mtk′, hk′), let the system master public key hk′=y′, the master trapdoor key mtk′=x′, and use the master trapdoor key mtk′ to calculate the new user key tk′ corresponding to the user identity CID. Here, a chameleon hash that supports dynamic trapdoors is used. When breaking through the inherent immutability of the blockchain, the dynamic update of the trapdoor can be achieved. Even if the key is stolen, the key held by the thief will become invalid after a period of time, thereby reducing the risk of malicious nodes holding the trapdoor for a long time and solving the security risks of trapdoor abuse and trapdoor leakage.

[0085] Step 8: The authority verifies whether the old trapdoor is successfully revoked. If so, it returns a verification success; otherwise, it returns a verification failure.

[0086] In one embodiment, the implementation of step 8 includes the following:

[0087] The authorization agency verifies the validity of the user key tk. If it is not within the validity period, it outputs Status = Success, that is, the old trapdoor cannot generate a valid hash value and the verification is successful. Otherwise, it outputs Status = Fail.

[0088] The present invention conducts experimental tests on the main process, and the experiments are carried out on a laptop equipped with PBC library (version 0.5.14) and openssl library (version 1.1.1). The device is configured with a 1.6-GHz 4-core CPU and 4GB RAM, and uses the Ubuntu18.04LTS (64-bit) operating system. In the experiment, the method of the present invention: Chameleon Hash with Dynamic Trapdoor (DTCH) is tested and compared with other methods: Threshold Chameleon Hash (TCH), Revocable Chameleon Hash (RCH), Chameleon Hash with Limited number of Redaction (RCHLR). In practical applications, the hash collision search algorithm and the hash verification algorithm are executed frequently, which can better reflect the efficiency of the chameleon hash scheme. Therefore, this experiment will execute multiple collision search algorithms and hash verification algorithms, and combine their computational costs to compare the computational costs between different methods (such as Figure 3As shown in Figure 1.1 ). Experimental data show that the algorithm of the present invention takes milliseconds to complete. Compared with other methods, it has the lowest computational cost. In addition, the present invention does not allow the same trapdoor to be reused, and can flexibly update the trapdoor. This fundamentally solves the security risks of trapdoor abuse and trapdoor leakage, achieves higher security guarantees at a lower computational cost, and realizes the organic integration of the editability and security credibility of the blockchain.

[0089] As mentioned above, the present invention proposes an editable blockchain scheme with dynamic trapdoors, and provides a specific structure with provable security based on bilinear mapping. The scheme uses controllable randomness so that only users with legitimate trapdoor keys can change the on-chain data, and the user key has time validity. When the user key expires or is used, the system will regenerate a new trapdoor and abolish the old trapdoor, reducing the risk of abuse of editing permissions and effectively solving the security problem after the trapdoor is leaked. Security analysis and related experimental results show that the present invention has good security, good operating efficiency at each stage, and achieves higher security guarantees at a lower computational cost.

Claims

1. An editable blockchain method supporting dynamic trapdoors, characterized in that: It involves four entities: certification body, authorization body, data user and data modifier. The specific steps are as follows: Step 1: The certification authority inputs the selected security parameters and outputs the public parameters; Step 2: The authorized institution inputs public parameters, generates the system master trapdoor key and the system master public key, and outputs the Chameleon hash master trapdoor key pair; Step 3: The data modifier sends his / her user ID to the authorization agency. The authorization agency inputs the Chameleon Hash master trapdoor key pair, the data modifier's user ID, the expiration date of the user key held by the data modifier, and returns the timestamp function, and outputs the data modifier's identity parameters and user key. Step 4: The data modifier inputs the system master public key, data modifier identity parameters, original information string and random number, and outputs the chameleon hash value corresponding to the original message; Step 5: The data modifier inputs the system master public key, chameleon hash value, original message string, random number, and new message string, and outputs a new chameleon hash value and a new random number; Step 6: The data modifier inputs the system master public key, chameleon hash value, original message string, random number, new message string, new chameleon hash value and new random number, data modifier identity parameter, user key, and verifies the validity of the user key and the correctness of the hash value; Step 7: The authorized institution cancels the existing Chameleon Hash master trapdoor key pair, i.e., the old trapdoor, and generates a new Chameleon Hash master trapdoor key pair, i.e., the new trapdoor. The updated trapdoor satisfies that the new trapdoor value does not depend on the old trapdoor value. Step 8: The authority verifies whether the old trapdoor is successfully revoked. If so, it returns a verification success; otherwise, it returns a verification failure.

2. The editable blockchain method supporting dynamic trapdoors according to claim 1, characterized in that: In step 1, the certification authority inputs the selected security parameter λ; selects the multiplicative cyclic group G and G with order q and generator g. T , where q represents a large prime number, g represents the generator number of G, and G and G T Represent two multiplicative cyclic groups; define two hash functions H:{0,1} * →G,H1:{0,1} * →Z q , where Z q represents a finite field of order q; e represents a bilinear map e: G×G→G T ; Output common parameter pp is {G,G T ,e,g,H,H1}.

3. The editable blockchain method supporting dynamic trapdoors according to claim 2, characterized in that: In step 2, the authorized institution inputs the public parameter pp, generates the system master trapdoor key mtk and the system master public key hk, and outputs the chameleon hash master trapdoor key pair (mtk, hk). The system master trapdoor key mtk is kept by the authorized institution, and the system master public key hk is made public. The process of generating the chameleon hash master trapdoor key pair is as follows: Select random number Calculate y = g x , run the algorithm to generate the master trapdoor key pair (mtk, hk), let the system master public key hk = y, the master trapdoor key mtk = x, where, Represents the set of integers consisting of 1, 2, …, q-1.

4. The editable blockchain method supporting dynamic trapdoors according to claim 3 is characterized in that: Step 3 includes the following sub-steps: 3.1: The data modifier sends his / her user identity CID to the authorized agency. 3.2: The authorized institution inputs the master trapdoor key pair (mtk, hk), the user identity identifier CID, and the user key usage period h of the data modifier. valid , timestamp function ctime(), generates a specific identity h for the data modifier, and outputs the data modifier identity parameter ID PP {CID,h valid ,h} and user key tk, and sent to the data modifier; the calculation formula of the specific identity h and user key tk is as follows: tk=h x 。 5. The editable blockchain method supporting dynamic trapdoor according to claim 4, characterized in that: In step 4, the data modifier enters the system master public key hk and the data modifier identity parameter ID PP , original information string m and random number r, output chameleon hash value CH: Where m∈{0,1} * ; r = g αx , 6. The editable blockchain method supporting dynamic trapdoors according to claim 5, characterized in that: In step 5, the data modifier inputs the system master public key hk, the chameleon hash value CH, the original message string m, the random number r, and the new message string m′, and outputs the new chameleon hash value CH′: Where m′∈{0,1} * ; r′ represents a new random number, 7. The editable blockchain method supporting dynamic trapdoor according to claim 6, characterized in that: In step 6, the data modifier enters the system master public key hk, the chameleon hash value CH, the original message string m, the random number r, the new chameleon hash value CH′, the new message string m′ and the new random number r′, and the data modifier identity parameter ID PP , user key tk, verify the validity of the user key and the correctness of the hash value, the specific implementation is as follows: Get the data modifier's identity parameter ID PP The user identity identifier CID in the user key tk and the specific identity identifier h in the user key tk are used to determine whether the user key is within the validity period. If not, Status = Expired is output; Get CH and CH′, and determine whether CH=CH′ is true. If so, output Status=Valid; otherwise, output Status=Invalid.

8. The editable blockchain method supporting dynamic trapdoors according to claim 7, characterized in that: In step 7, the specific execution is as follows: The authorized institution enters the public parameter pp and selects a random number Calculate y′=g x′ , output a new Chameleon hash master trapdoor key pair (mtk′, hk′), let the system master public key hk′=y′, the master trapdoor key mtk′=x′, and use the master trapdoor key mtk′ to calculate the new user key tk′ corresponding to the user identity CID.

9. The editable blockchain method supporting dynamic trapdoors according to claim 8, characterized in that: In step 8, the authorization agency verifies the validity of the user key tk. If it is not within the validity period, it outputs Status=Success, that is, the old trapdoor cannot generate a valid hash value, verifying that the old trapdoor is successfully revoked, otherwise it outputs Status=Fail.

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