A blockchain-based archive management system

Abstract

The present invention relates to the field of information technology, and in particular to a file management system based on blockchain, comprising a receiving module, a storage module, a storage module and a time-limited sharing module, wherein the receiving module receives a scanned copy and description information of a file, the storage module extracts a hash value of the scanned copy, the storage module stores the scanned copy, the storage module establishes an index of the scanned copy, the time-limited sharing module receives a read request from other departments, and after the time-limited sharing module verifies that the department has the authority to handle the corresponding matter, reads the scanned copy whose query key value matches the retrieval key value and the file type matches the type, adds a watermark containing the matter information to the scanned copy, encrypts the scanned copy using a time-limited encryption algorithm, obtains a time-limited ciphertext, sends the time-limited ciphertext to the requesting department, and the requesting department decrypts the time-limited ciphertext within the time limit to obtain the file. The substantial effect of the present invention is to reduce the cost of file management and improve the efficiency of departments in handling related matters.

Description

Technical Field

[0001] The present invention relates to the field of information technology, and in particular to a file management system based on blockchain. Background Art

[0002] Archives are certificates for recording rights and interests, and they are original records. When there are disputes over rights and interests, archives will serve as an important basis for investigation. It is precisely because archives have original records and voucher effect that archives are still mainly kept in paper form. Preserving archives in paper form not only requires a special venue, but also has high storage costs, and is not easy to find and share. As a result, archives are usually not used again after being preserved, and the social benefits of archives are difficult to play. Blockchain is a decentralized distributed storage technology. The data stored on the blockchain has the characteristics of being tamper-proof, transparent and traceable, and can therefore provide credible proof. Providing new archive management technology with the help of blockchain is an important research topic at present.

[0003] For example, Chinese patent CN114005499A, published on February 1, 2022, discloses a blockchain-based archive sharing management platform, including the following steps: Step 1: Archive entry: enter the required archive information into the system; use the system to store archives; Step 2: Archive sorting: sort the input archives, trace and track the information in the archives in a targeted manner, and prevent tampering; Step 3: Archive classification: distinguish them according to the type of archives; the whole is divided into three major types: general archives; key archives and special archives; Step 4: Archive analysis: analyze the management encryption required according to the type of archives. Its technical solution can effectively ensure the security of data and improve the safety of use. However, its technical solution cannot solve the problem of low efficiency of archive management. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the current archive management cost is high and it is not convenient to share. A blockchain-based archive management system is proposed, which can reduce the archive management cost and can share archives safely and conveniently.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a blockchain-based archive management system, comprising a receiving module, a storage module, a storage module and a limited-time sharing module, wherein the receiving module receives a scanned copy and description information of the archive, wherein the description information includes the archive type and the query key value, the storage module extracts the hash value of the scanned copy, uploads the hash value to the blockchain storage, and obtains the corresponding block height, the storage module stores the scanned copy, and the storage module establishes an index of the scanned copy, wherein the index records the file storage address, the archive type, the query key value, the hash value and the storage block height, the limited-time sharing module receives a read request from other departments, wherein the read request includes department information, a search key value, a type and matter information, and after the limited-time sharing module verifies that the department has the authority to handle the corresponding matter, reads the scanned copy whose query key value matches the search key value and whose archive type matches the type, adds a watermark containing the matter information to the scanned copy, encrypts the scanned copy using a limited-time encryption algorithm, obtains a limited-time ciphertext, sends the limited-time ciphertext to the requesting department, and the requesting department decrypts the limited-time ciphertext within the limited time to obtain the archive.

[0006] Preferably, the limited-time sharing module stores a table of fields required for the matter, and the description information also records the field type and location information recorded on the scanned copy. The limited-time sharing module receives a read request from other departments, and after verifying that the department has the authority to handle the corresponding matter, reads the scanned copy, adds a watermark containing the matter information to the scanned copy, and then determines whether the field types recorded on the scanned copy all belong to the fields required for the corresponding matter. If there are field types that do not belong to the fields required for the corresponding matter, an occlusion watermark is generated based on the location information of the field, and the occlusion watermark obscures the content of the corresponding field.

[0007] Preferably, the time-limited sharing module publishes a smart contract on the blockchain, and the smart contract includes several encrypted columns, and the encrypted columns include column identifiers, clocks, and public notice columns. The public notice column displays m sample points (xi, yi), i∈[1, m]. When the clock counts down to 0, the encrypted column clears the public notice column and resets the clock to an initial value. The time-limited sharing module encrypts the scanned copy using a symmetric encryption algorithm to obtain a primary ciphertext, and the secret key is recorded as Key. The time-limited sharing module generates an integer n, selects an encrypted column whose clock matches the time-limited duration, and if there is no matching clock, selects the clock with the initial value and sets it to the time-limited duration to obtain the corresponding public notice. m sample points in the public notice column, generate a univariate polynomial passing through n of the m sample points, calculate the distances between the remaining mn sample points and the univariate polynomial, and record the sum of the distances as the sample distance. The univariate polynomial with the smallest sample distance is used as the encryption polynomial, and the encryption polynomial is used to encrypt the Key. The primary ciphertext, the ciphertext Key, and the integer n are sent to the requesting department. The requesting department reads the sample points in the public notice column within a time limit, and exhaustively lists the univariate polynomials passing through n of the m sample points. The univariate polynomial with the smallest sample distance is the restoration polynomial, and the restoration polynomial is used to decrypt the ciphertext Key. The primary ciphertext is decrypted using the secret key Key to obtain a shared scan.

[0008] Preferably, when the limited-time sharing module uses an encryption polynomial to encrypt the Key, the following steps are performed: convert the secret key Key into a binary stream, fill in the bits according to preset rules, truncate it into several binary segments of preset lengths, and convert the binary segments into integers D; generate a data combination (b1, x1, b2, x2, …, bN, xN, △), where bi is a positive integer, such that D = ∑(-1)^bi*floor(bi / 2)*f(xi)+△, where i∈[1,N], △ is a correction value, and floor() is a downward forensic function; and combine the data combinations in sequence as the ciphertext Key.

[0009] Preferably, a matter list and a matter association list are manually prepared and stored in the time-limited sharing module, wherein the matter list records the types of files required for the matters, and the matter association list records the intervals and probabilities of handling several other matters after handling the matters. After the time-limited sharing module encrypts the files and uploads them to the blockchain, it reads the matter association list. If, after the current matter is handled, there are other matters whose probability of handling is greater than a preset threshold, the matter list is read to obtain the types of files required for the other matters, and the scanned copies whose query key values ​​match the retrieval key values ​​under the corresponding file types are read. The scanned copies are encrypted using a time-limited encryption algorithm and uploaded to the blockchain, and the requesting department decrypts them within the time limit to obtain the files required for handling the next matter.

[0010] Preferably, the encryption bar also includes a second clock and a prompt bar, the prompt bar is initially hidden, when the second clock counts down to 0, the prompt bar is displayed and the clock is started, when the clock counts down to 0, the clock and the second clock are reset, if after the current item is handled, there are other items whose handling probability is greater than a preset threshold, then a corresponding scan is obtained, recorded as an associated scan, the associated scan is encrypted using the secret key Key2, an associated secondary ciphertext is obtained, the associated secondary ciphertext is associated with a random identifier and uploaded to the blockchain for storage, the clock of the initial value is selected and set to a time limit, the corresponding second clock is set to an interval time, the clock is set to a time limit, and the corresponding The m sample points in the public notice column generate an integer n, obtain the corresponding encryption polynomial, use the encryption polynomial to encrypt the secret key Key2, obtain the Key2 ciphertext, encrypt the Key2 ciphertext, the integer n and the random identifier using the public key of the requesting department and write them into the prompt column. When the second clock counts down to 0, the requesting department polls the blockchain and tries to decrypt with the private key to obtain the Key2 ciphertext, the integer n and the random identifier. The m sample points are read, and the recovery polynomial is obtained according to the integer n. The recovery polynomial is used to decrypt to obtain the secret key Key2. The blockchain is queried to obtain the associated secondary ciphertext corresponding to the random identifier, and the associated scan is obtained by decrypting with the secret key Key2.

[0011] The substantial effects of the present invention are as follows: by storing archive scans through blockchain, authenticity proof is provided for the scans, so that paper copies no longer need to be saved, and electronic scans are easier to store and access, thus reducing archive management costs; by providing corresponding archives to authorized departments through a limited-time sharing module, the efficiency of departments in handling related matters can be improved; and by improving the limited-time encryption algorithm, the security of limited-time encryption is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the archive management system of Example 1.

[0013] Figure 2 This is a schematic diagram of a time-limited encryption algorithm according to Embodiment 1.

[0014] Figure 3 This is a schematic diagram of encryption polynomial encryption in Example 1.

[0015] Figure 4 This is a schematic diagram of a method for limited-time sharing of associated scans according to Example 1.

[0016] Among them: 10. Receiving module, 11. Scanned copy, 12. Description information, 20. Evidence storage module, 30. Storage module, 40. Limited time sharing module, 50. Blockchain. DETAILED DESCRIPTION

[0017] The specific implementation of the present invention will be further described below through specific examples in conjunction with the accompanying drawings.

[0018] Embodiment 1:

[0019] A blockchain-based archive management system, please see the attached Figure 1 , including a receiving module 10, a proof module 20, a storage module 30 and a limited-time sharing module 40, the receiving module 10 receives a scanned copy 11 of the file and description information 12, the description information 12 includes the file type and the query key value, the proof module 20 extracts the hash value of the scanned copy 11, uploads the hash value to the blockchain 50 for storage, obtains the corresponding block height, the storage module 30 stores the scanned copy 11, and the storage module 30 establishes an index of the scanned copy 11, and the index records the file storage address, the file type, the query key value, the hash value and the proof block height The time-limited sharing module 40 receives a read request from other departments, the read request includes department information, search key value, type and matter information. After verifying that the department has the authority to handle the corresponding matter, the time-limited sharing module 40 reads the scanned copy 11 whose query key value matches the search key value and whose file type matches the type, adds a watermark containing the matter information to the scanned copy 11, encrypts the scanned copy 11 using a time-limited encryption algorithm, obtains a time-limited ciphertext, sends the time-limited ciphertext to the requesting department, and the requesting department decrypts the time-limited ciphertext within the time limit to obtain the file.

[0020] After the archive scan 11 is stored in the blockchain 50, the archive scan 11 cannot be tampered with, thereby providing authenticity proof for the archive scan 11, making the archive scan 11 valid as a voucher. It is very convenient to complete the search and sharing of archives in an electronic form. Archives and archive scans 11 are generated by trusted departments, and can be searched and shared by the limited-time sharing module 40 when handling related matters later.

[0021] Table 1 Archive Index

[0022] File Name 800255820014 800255820015 File storage address .. / data / 8014.jpg .. / data / 8015.jpg File Type Small and Micro Enterprise Subsidy Registration Form Small and Micro Enterprise Subsidy Registration Form Query key value {Company name: A} {Company name: B} Hash value E7F312…8E7201 C606E3…18D775 Evidence block height 104451023 104451023

[0023] As shown in Table 1, a local industrial and commercial department handles special subsidy registration for small and micro enterprises. After scanning the relevant registration files, the scanned copy 11 is recorded and stored to create an index. The relevant enterprises can be queried by checking the company name. When the tax department handles taxes for small and micro enterprises that are eligible for subsidies, there are also relevant tax exemptions. The corresponding small and micro enterprises can directly apply for tax exemptions with the "Small and Micro Enterprise Subsidy Registration Form" as a voucher. After adopting this system, the tax department can directly request relevant files from the background to the limited-time sharing module 40 and submit a read request. After obtaining the corresponding scanned copy 11 of the "Small and Micro Enterprise Subsidy Registration Form", tax exemptions can be directly handled for the corresponding small and micro enterprises.

[0024] The limited-time sharing module 40 stores a table of fields required for the matter, and the description information 12 also records the field type and location information recorded on the scanned copy 11. The limited-time sharing module 40 receives a read request from other departments, and after verifying that the department has the authority to handle the corresponding matter, reads the scanned copy 11, adds a watermark containing the matter information to the scanned copy 11, and then determines whether the field types recorded on the scanned copy 11 all belong to the fields required for the corresponding matter. If there is a field type that does not belong to the field required for the corresponding matter, an obstruction watermark is generated according to the location information of the field, and the obstruction watermark obscures the content of the corresponding field.

[0025] The limited-time sharing module 40 publishes a smart contract on the blockchain 50. The smart contract includes several encrypted columns, which include column identifiers, clocks, and public notice columns. The public notice column displays m sample points (xi, yi), i∈[1, m]. When the clock counts down to 0, the encrypted column clears the public notice column and resets the clock to the initial value. Figure 2 The time-limited encryption algorithm includes: step A01) the time-limited sharing module 40 uses a symmetric encryption algorithm to encrypt the scanned document 11 to obtain a primary ciphertext, and the secret key is recorded as Key; step A02) the time-limited sharing module 40 generates an integer n, and selects an encryption column whose clock matches the time-limited duration; step A03) if there is no matching clock, the clock of the initial value is selected as the time-limited duration; step A04) m sample points of the corresponding public notice column are obtained, and a univariate polynomial is generated passing through n of the m sample points; step A05) the distance between the remaining mn sample points and the univariate polynomial is calculated, and the sum of the distances is recorded as sample points. This distance; Step A06) The univariate polynomial with the smallest sample distance is used as the encryption polynomial; Step A07) The encryption polynomial is used to encrypt the Key, and the primary ciphertext, the ciphertext Key and the integer n are sent to the requesting department; Step A08) The requesting department reads the sample points in the public notice column within the time limit, and exhaustively lists the univariate polynomials of n sample points among the m sample points; Step A09) The univariate polynomial with the smallest sample distance is the restoration polynomial; Step A10) The restoration polynomial is used to decrypt the ciphertext Key, and the primary ciphertext is decrypted using the secret key Key to obtain the shared scanned copy 11. The contents recorded in the smart contract are shown in Table 2, which records a total of 60 encryption columns, and can provide 60 sets of time-limited encryption with different time limits.

[0026] Table 2 Smart Contract

[0027] Encryption column 1 {bar logo 1, clock 1, notice bar 1} Encryption column 2 {bar logo 2, clock 2, notice bar 2} Encryption column 3 {bar logo 3, clock 3, notice bar 3} … … Encryption column 60 {bar logo 60, clock 60, notice bar 60}

[0028] There are 4 sample points recorded in Public Column 2, namely (2,16), (4,24), (8,36) and (12,64). When n is 2, the univariate polynomials that pass through 2 of the 4 sample points are shown in Table 3. The univariate polynomial y=5x+4 with the smallest sample distance is selected as the encryption polynomial.

[0029] Table 3 Univariate polynomial and sample distance table when n=2

[0030] Serial number Univariate Polynomial Sample distance 1 y=4x+8 12 2 3y=10x+28 16 3 y=4.8x+6.4 10.4 4 y=3x+12 18 5 y=5x+4 10 6 y=7x+-20 38

[0031] Please refer to the attached Figure 3 When the limited-time sharing module 40 uses the encryption polynomial to encrypt Key, the following steps are performed: Step B01) Convert the secret key Key into a binary stream, fill in the bits according to the preset rules, truncate it into a number of binary segments of preset lengths, and convert the binary segments into integers D; Step B02) Generate a data combination (b1, x1, b2, x2, …, bN, xN, △), where bi is a positive integer, such that D = ∑ (-1) ^ bi * floor (bi / 2) * f (xi) + △, where i ∈ [1, N], △ is the correction value, and floor () is the downward forensic function; Step B03) Combine the data combinations in order as the ciphertext Key. For example, if the key is "EuWk", in ASCII encoding, the string EuWk is converted to binary as follows: 01000101 01110101 01010111 01101011, and truncated to two integers according to the length of 2 bytes, namely D1=17781 and D2=22379. The univariate polynomial f(x) is: f(x)=15*x^2-32*x+64. Then D1 can be expressed as D1=6*f(7)+ f(31)+844, and the corresponding data combination is (12,7,2,31,844). The data combination of integer D2 can be obtained in the same way.

[0032] The item list and item association list are manually prepared and stored in the time-limited sharing module 40. The item list records the types of files required for the items, and the item association list records the interval time and the probability of handling several other items after handling the item. After the time-limited sharing module 40 encrypts the file and uploads it to the blockchain 50, it reads the item association list. If there are other items with a handling probability greater than a preset threshold after the current item is handled, the item list is read to obtain the types of files required for the other items, and the scanned copy 11 with the query key value matching the search key value under the corresponding file type is read. The scanned copy 11 is encrypted using a time-limited encryption algorithm and uploaded to the blockchain 50. The requesting department decrypts it within the time limit to obtain the files required for handling the next item.

[0033] The beneficial technical effects of this embodiment are: the archive scan 11 is stored through the blockchain 50 to provide authenticity proof for the scan 11, so that there is no need to save the paper copy, and the electronic scan 11 is more convenient for storage and reference, reducing the cost of archive management; the limited-time sharing module 40 is used to provide the corresponding archives to the authorized department, which can improve the efficiency of the department in handling related matters; the security of the limited-time encryption is improved through the improved limited-time encryption algorithm.

[0034] Embodiment 2:

[0035] A file management system based on blockchain, this embodiment makes specific improvements to the smart contract for time-limited encryption. As shown in Table 4, the encryption column of the smart contract in this embodiment also includes a second clock and a prompt column.

[0036] Table 4 Smart Contract

[0037] Encryption column 1 {bar logo 1, clock 1, second clock 1, prompt bar 1, public notice bar 1} Encryption column 2 {bar logo 2, clock 2, second clock 2, prompt bar 2, public notice bar 2} Encryption column 3 {bar logo 3, clock 3, second clock 3, prompt bar 3, public notice bar 3} … … Encryption column 60 {bar logo 60, clock 60, second clock 60, prompt bar 60, public notice bar 60}

[0038] The prompt bar is initially hidden. When the second clock counts down to 0, the prompt bar is displayed and the clock is started. When the clock counts down to 0, the clock and the second clock are reset.

[0039] Please refer to the attached Figure 4 , if there is another matter whose handling probability is greater than the preset threshold after the current matter, then execute: Step C01) obtain the corresponding scan 11, recorded as the associated scan 11; Step C02) encrypt the associated scan 11 using the secret key Key2 to obtain the associated secondary ciphertext; Step C03) associate the associated secondary ciphertext with the random identifier and upload it to the blockchain 50 for storage; Step C04) select the clock of the initial value and set it to the time limit duration, set the corresponding second clock to the interval duration, and set the clock to the time limit duration; Step C05) read the m sample points of the corresponding public notice column, generate an integer n, and obtain the corresponding encryption polynomial; Step C06) use The encryption polynomial encrypts the secret key Key2 to obtain the Key2 ciphertext; Step C07) Encrypt the Key2 ciphertext, integer n and random identifier using the public key of the requesting department and write them into the prompt column; Step C08) When the second clock counts down to 0, the requesting department polls the blockchain 50 and attempts to decrypt using the private key to obtain the Key2 ciphertext, integer n and random identifier; Step C09) Read m sample points and obtain the recovery polynomial according to the integer n; Step C10) Decrypt using the recovery polynomial to obtain the secret key Key2, query the blockchain 50 to obtain the associated secondary ciphertext corresponding to the random identifier, and decrypt using the secret key Key2 to obtain the associated scanned copy 11. Compared with the first embodiment, this embodiment can provide other departments with more convenient sharing of archive scanned copies 11, thereby improving the efficiency of departmental work.

[0040] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A blockchain-based archive management system, characterized in that: It includes a receiving module, a proof module, a storage module and a limited-time sharing module. The receiving module receives a scanned copy and description information of an archive, wherein the description information includes the archive type and a query key value. The proof module extracts a hash value of the scanned copy, uploads the hash value to the blockchain storage, and obtains a corresponding block height. The storage module stores the scanned copy, and the storage module establishes an index of the scanned copy. The index records the file storage address, the archive type, the query key value, the hash value, and the proof block height. The limited-time sharing module receives a read request from other departments, wherein the read request includes department information, a search key value, a type, and event information. After the limited-time sharing module verifies that the department has the authority to handle the corresponding event, it reads a scanned copy whose query key value matches the search key value and whose archive type matches the type, adds a watermark containing the event information to the scanned copy, encrypts the scanned copy using a limited-time encryption algorithm, obtains a limited-time ciphertext, and sends the limited-time ciphertext to the requesting department. The requesting department decrypts the limited-time ciphertext within the time limit to obtain the archive. The time-limited sharing module publishes a smart contract on the blockchain. The smart contract includes several encrypted columns, which include column identifiers, clocks, and public notice columns. The public notice column displays m sample points (xi, yi), i∈[1, m]. When the clock counts down to 0, the encrypted column clears the public notice column and resets the clock to the initial value. The time-limited sharing module uses a symmetric encryption algorithm to encrypt the scanned copy to obtain a primary ciphertext, and the secret key is recorded as Key. The time-limited sharing module generates an integer n, selects an encrypted column whose clock matches the time-limited duration, and if there is no matching clock, selects the clock with the initial value and sets it to the time-limited duration to obtain the corresponding public notice column. m sample points, generate a univariate polynomial passing through n of the m sample points, calculate the distances between the remaining mn sample points and the univariate polynomial, and record the sum of the distances as the sample distance. The univariate polynomial with the smallest sample distance is used as the encryption polynomial, and the encryption polynomial is used to encrypt the Key. The primary ciphertext, the ciphertext Key, and the integer n are sent to the requesting department. The requesting department reads the sample points in the public notice column within a time limit, and exhaustively lists the univariate polynomials passing through n of the m sample points. The univariate polynomial with the smallest sample distance is the restoration polynomial, and the restoration polynomial is used to decrypt the ciphertext Key. The primary ciphertext is decrypted using the secret key Key to obtain a shared scan.

2. According to claim 1, a blockchain-based archive management system is characterized in that: The limited-time sharing module stores a table of fields required for the matter, and the description information also records the field type and location information recorded on the scanned copy. The limited-time sharing module receives a read request from other departments, and after verifying that the department has the authority to handle the corresponding matter, reads the scanned copy, adds a watermark containing the matter information to the scanned copy, and then determines whether the field types recorded on the scanned copy all belong to the fields required for the corresponding matter. If there are field types that do not belong to the fields required for the corresponding matter, an occlusion watermark is generated based on the location information of the field, and the occlusion watermark obscures the content of the corresponding field.

3. According to the blockchain-based archive management system of claim 1, it is characterized in that: When the time-limited sharing module uses the encryption polynomial to encrypt the Key, the following steps are performed: The secret key Key is converted into a binary stream, and after padding according to a preset rule, it is truncated into a number of binary segments of a preset length, and the binary segment is converted into an integer D; Generate a data combination (b1,x1,b2,x2,…,bN,xN,△), bj is a positive integer, so that D=∑(-1)^bj*floor(bj / 2)*f(xj)+△, where j∈[1,N], △ is the correction value, floor() is the downward forensic function, and f(xj) is a univariate polynomial; Combine the data in order as the ciphertext Key.

4. According to the blockchain-based archive management system of claim 1, it is characterized in that: The item list and item association list are manually prepared and stored in the time-limited sharing module. The item list records the types of files required for the items, and the item association list records the interval time and handling probability of several other items after the item is handled. After the time-limited sharing module encrypts the file and uploads it to the blockchain, it reads the item association list. If there are other items with a handling probability greater than a preset threshold after the current item is handled, the item list is read to obtain the types of files required for the other items, read the scanned copy with the query key value matching the retrieval key value under the corresponding file type, encrypt the scanned copy using a time-limited encryption algorithm and upload it to the blockchain, and the requesting department decrypts it within the time limit to obtain the file required for handling the next item.

5. According to claim 4, a blockchain-based archive management system is characterized in that: The encryption bar also includes a second clock and a prompt bar. The prompt bar is initially hidden. When the second clock counts down to 0, the prompt bar is displayed and the clock is started. When the clock counts down to 0, the clock and the second clock are reset. If there are other matters with a probability of handling greater than a preset threshold after the current matter, the corresponding scanned copy is obtained and recorded as an associated scanned copy. The associated scanned copy is encrypted using the secret key Key2 to obtain an associated secondary ciphertext. The associated secondary ciphertext is associated with a random identifier and uploaded to the blockchain for storage. The clock with the initial value is set to the time limit duration, the corresponding second clock is set to the interval duration, the clock is set to the time limit duration, and the corresponding public notice bar is read. m sample points, generate an integer n, obtain the corresponding encryption polynomial, use the encryption polynomial to encrypt the secret key Key2, obtain the Key2 ciphertext, encrypt the Key2 ciphertext, the integer n and the random identifier using the public key of the requesting department and write them into the prompt bar. When the second clock counts down to 0, the requesting department polls the blockchain and tries to decrypt with the private key to obtain the Key2 ciphertext, the integer n and the random identifier. m sample points are read, and the recovery polynomial is obtained according to the integer n. The recovery polynomial is used to decrypt to obtain the secret key Key2. The blockchain is queried to obtain the associated secondary ciphertext corresponding to the random identifier, and the associated scan is obtained by decrypting with the secret key Key2.

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