Attribute-based encryption method and system supporting multi-authority responsibility-traceable and outsourcing calculation

Abstract

The invention discloses an attribute-based encryption method and system based on support of multi-authority accountability and outsourcing calculation, and the method specifically comprises the steps: introducing a multi-attribute authority mechanism to be responsible for key distribution and management, reducing the dependence on a single mechanism, and improving the safety and reliability of the system; the cloud server locally updates the access strategy and the ciphertext according to the minimum change increment set uploaded by the data owner; a white-box tracking technology is adopted to bind a user identity with an attribute key, so that a system can locate a specific identity of a malicious user and a specific identity of a malicious attribute authority through a leaked key; intensive computing tasks in the encryption and decryption processes are outsourced to a cloud server, and meanwhile it is ensured that user privacy is not leaked in the outsourcing process; for the untrusted problem of the cloud server, the calculation result is verified by using the smart contract in the block chain, and it is ensured that the verification process is open and transparent and the result is trusted; and an attribute version mark is introduced, so that efficient revocation of old version attributes is realized, and the safety is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data security and privacy protection, and particularly relates to an attribute-based encryption method and system supporting multi-authority traceability and outsourcing computation. BACKGROUND

[0002] Under the background of the rapid development of emerging information technologies such as the Internet of Things and cloud computing, many individual and enterprise users choose to outsource a large amount of data generated by Internet of Things devices to public clouds for storage and sharing. Although this mode brings users a convenient cloud service experience, it also raises new security problems. First, data outsourcing storage leads to the separation of data ownership and management rights, which significantly increases the risk of data leakage and unauthorized access. Second, the trustworthiness of third-party cloud servers cannot be ignored, and cloud service providers may tamper with or delete user data due to interest-driven.

[0003] In order to solve these problems, users usually encrypt the data before outsourcing storage. Although symmetric encryption and traditional public key encryption technology can protect the confidentiality of data, they have obvious limitations in practical application. For example, these technologies can only support one-to-one data sharing and cannot meet the demand for fine-grained access control in multi-user scenarios. In addition, the complexity of key management and the risk of key leakage also limit their widespread application.

[0004] In contrast, the attribute-based encryption technology represented by Ciphertext Policy Attribute-Based Encryption (CP-ABE) can realize one-to-many fine-grained access control while ensuring data confidentiality, thereby significantly improving the security of data sharing. However, although traditional attribute-based encryption technology has certain advantages in data security, it still has problems of insufficient privacy protection and high computational overhead in practical applications. First, the traditional single-authority attribute-based encryption scheme has obvious limitations in distributed large-scale application scenarios. Single-point failure and performance bottleneck problems make the system difficult to run efficiently in a distributed environment. Second, when modifying the access rights of data blocks, the data owner needs to redesign the policy and re-encrypt the data, and then upload the updated ciphertext to the cloud server. This will increase the computational and communication costs, and frequent adjustment of access policies will further increase the burden and complexity of data management. Third, once the key is leaked, existing technologies are difficult to quickly and accurately locate the identity of the malicious user or the identity of the malicious attribute authority, which poses a risk to the security and accountability of the system. Fourth, the battery capacity and computing resources of Internet of Things terminal devices are limited, making it difficult to efficiently support the expensive computational needs during encryption and decryption processes, which limits the widespread application of traditional attribute-based encryption technology in Internet of Things scenarios. Fifth, when the system undergoes attribute changes, the old version of the attribute can be revoked in a timely manner, and the key and ciphertext are updated, so that the key and ciphertext related to the old version of the attribute are invalidated. Finally, in an untrusted cloud server, data may be tampered with due to interest-driven or technical vulnerabilities, or incorrect results may be returned during the calculation process, thereby affecting the reliability and data integrity of the system. SUMMARY

[0005] To solve the technical problems in the prior art, the present application combines blockchain technology and proposes a CP-ABE method and system that supports multi-authority accountability and outsourcing computation. A multi-attribute authority is introduced to be responsible for key distribution and management, dynamic authorization technology is used to enable the cloud server to update the access policy and ciphertext locally, white-box tracking technology is used to track malicious users, intensive computation during encryption and decryption is outsourced to the cloud server, and blockchain is used to verify the correctness of the outsourcing computation result. Version marking technology is used to revoke old version attributes in the system, further enhancing the security of the system.

[0006] To achieve the above purpose, the first aspect of the present application provides an attribute-based encryption method supporting multi-authority accountability and outsourcing computation, comprising: The central authority initializes to generate system public parameters, master keys, user identities, and attribute authority identities, and the attribute authority initializes to generate a set of attribute public keys and a set of attribute private keys; The attribute authority generates a key corresponding to the attribute set submitted by the user based on system public parameters, the attribute set submitted by the user and an attribute private key set; The cloud server generates outsourcing encryption ciphertext based on system public parameters, the data owner calls the smart contract to verify the outsourcing encryption ciphertext based on system public parameters, and then locally encrypts the encryption plaintext based on system public parameters, outsourcing encryption ciphertext, an access policy, an attribute domain and an attribute public key set to obtain data ciphertext encrypted by the access policy; The cloud server updates the access policy and the ciphertext locally according to the minimum change increment set uploaded by the data owner; The data accessor decrypts the locally updated ciphertext and the data ciphertext based on system public parameters and the user attribute key to obtain plaintext.

[0007] In an embodiment, the attribute authority and the central authority generate an attribute key corresponding to the attribute set submitted by the user based on system public parameters, the attribute set submitted by the user and an attribute private key set, comprising: The user submits an attribute set to the attribute authority that manages the attribute of the user ; Verify the legality of the attribute, if failed, terminate, otherwise calculate , is an intermediate value, H is a hash function, is the identity of the user, is a timestamp; For each attribute , extract the attribute value and the version number , calculate , generate an intermediate key , , , is an intermediate value, and is a public parameter, is the attribute set; The central authority synthesizes the final key, comprising: randomly selecting , calculating , , , , outputting the user key , , , , , is an element in the user key, from the master key, is a set of attributes.

[0008] In an embodiment, the cloud server generates the outsourced encryption ciphertext based on the system public parameters, comprising: The cloud server randomly selects , calculates the base component: , wherein, is a group, is a bilinear mapping, is a generator, from the master key, , is the base component; to to , randomly select , , , calculate , , , , wherein, , , , , is a component of the outsourced ciphertext, is the size of the outsourcing pool; output the outsourced encryption ciphertext ; .

[0009] In an embodiment, the data owner calls the smart contract to verify the outsourced encryption ciphertext based on the system public parameters, comprising: Randomly select a random number , the following calculations are performed:

[0010]

[0011]

[0012] wherein, and are batch coefficients of the outsourced encryption verification process, is the product aggregation item of the verification process; verify whether the equation: is established, if the equation is established, it indicates that the verification is passed, otherwise the verification fails.

[0013] In an embodiment, the data owner encrypts the plaintext to be encrypted locally based on the system public parameters, the outsourced encryption ciphertext, the access policy, the attribute domain and the attribute public key set, to obtain a data ciphertext encrypted by the access policy, including: The data owner defines the access policy , wherein is a matrix, is a mapping function for mapping the rows of the matrix to attribute names, is an attribute value; The real attribute value in is replaced by a random value ; The secret sharing is calculated, including: randomly selecting , a vector , calculating , is an intermediate value; The ciphertext is constructed, and is calculated to , , , wherein , , , is a component of the data ciphertext, is the plaintext, and are is an attribute key parameter maintained by the data owner, is a random mask introduced by the data owner in the local encryption of the row; The verification tag is generated; The data ciphertext is output.

[0014] In an embodiment, the data accessor decrypts the locally updated ciphertext and the data ciphertext based on the system public parameters and the user attribute key to obtain the plaintext, including: The data accessor generates an outsourced decryption key and a user decryption key based on the system public parameters and the user attribute key; The data accessor obtains a form-modified ciphertext based on the locally updated ciphertext and the user decryption key; The data accessor generates a partially decrypted ciphertext pre-decrypted by the cloud server according to the system public parameters, the form-modified ciphertext and the outsourced decryption key; The data accessor calls the smart contract to verify the partially decrypted ciphertext to obtain a verification result; The data visitor decrypts the data ciphertext based on the partially decrypted ciphertext and the user decryption key to obtain decrypted plaintext.

[0015] In an implementation, the method further comprises revoking the attribute of the old version by using a version marking technique.

[0016] In an implementation, the method further comprises binding the user identity to the attribute key by using a white-box tracking technique to track malicious users and malicious attribute authorities.

[0017] Based on the same inventive concept, the second aspect of the application provides an attribute-based encryption system supporting multi-authority accountability and outsourced computation, comprising: a system initialization module configured to initialize a central authority to generate system public parameters, user identities and attribute authority identities, and initialize an attribute authority to generate an attribute public key set and an attribute private key set; a key generation module configured to generate a key corresponding to a set of attributes submitted by a user based on the system public parameters, a master key, the set of attributes submitted by the user and the attribute private key set by the attribute authority; a data encryption module configured to generate an outsourced encryption ciphertext based on the system public parameters by a cloud server, verify the outsourced encryption ciphertext based on the system public parameters by a data owner calling a smart contract, and then locally encrypt a plaintext to be encrypted based on the system public parameters, the outsourced encryption ciphertext, an access policy, an attribute domain and the attribute public key set to obtain a data ciphertext encrypted by the access policy; a policy update module configured to update the access policy and the ciphertext locally according to a minimum change increment set uploaded by the data owner by a cloud server; a data decryption module configured to decrypt the locally updated ciphertext and the data ciphertext based on the system public parameters and the attribute key of the user by a data visitor to obtain the plaintext.

[0018] In an implementation, the system further comprises a malicious user tracking module configured to track malicious users by binding the user identity to the attribute key by using a white-box tracking technique.

[0019] Compared with the prior art, the application has the following advantages and beneficial technical effects: (1) The present application reduces the dependence on a single authority by setting up a multi-attribute authorization mechanism to share key management tasks, thereby improving system security; a dynamic authorization mechanism is used to enable the cloud server to perform partial updates on the access strategy according to the minimum change increment set uploaded by the data owner; a white-box tracking mechanism is used to bind user identity and attribute keys, thereby achieving precise tracking of malicious users who leak keys; at the same time, the calculation efficiency is optimized, part of the encryption and decryption process is outsourced to the cloud server, thereby reducing the burden on the user and protecting privacy. By marking the attribute version, the binding of the attribute and the key and the ciphertext is realized, and when the attribute is updated, the system will update the ciphertext and the key in time, so that the key and the ciphertext related to the old version of the attribute are invalid, thereby further enhancing the security of the system.

[0020] (2) Compared with the prior art without using a blockchain, the present application realizes the correctness of the encryption and decryption outsourcing calculation results based on a blockchain, and the result verification stage is executed by the smart contract in the blockchain, thereby ensuring the fairness and credibility of the verification result. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 The flowchart of the attribute-based encryption method supporting multi-authoritative traceability and outsourcing calculation in the embodiments of the present application; Figure 2 The module diagram of the attribute-based encryption system supporting multi-authoritative traceability and outsourcing calculation in the embodiments of the present application; Figure 3 The model architecture diagram of the attribute-based encryption system supporting multi-authoritative traceability and outsourcing calculation in the embodiments of the present application. DETAILED DESCRIPTION

[0023] The application discloses a CP-ABE method supporting multi-authority accountability and outsourcing computing, and specifically comprises the following steps: a multi-attribute authority institution is responsible for key distribution and management by introducing multiple attribute authority institutions (attribute authorization institutions), thereby reducing the dependence on a single institution and improving the security and reliability of the system; dynamic authorization, in which a cloud server locally updates an access strategy and ciphertext according to a minimum change increment set uploaded by a data owner, instead of the data owner uploading the access strategy and ciphertext after a full update; malicious user tracking, in which a white-box tracking technology is adopted to bind a user identity and an attribute key, so that the system can locate the specific identity of a malicious user and the specific identity of a malicious attribute authority through a leaked key; efficient computing, in which the scheme outsources intensive computing tasks in the encryption and decryption processes to a cloud server to reduce the computing burden of a user end, while ensuring that the outsourcing process does not leak user privacy, thereby further improving the efficiency; outsourcing computing result verification, in which the scheme verifies a computing result by using a smart contract in a block chain to ensure that the verification process is open and transparent and the result is reliable; attribute revocation, in which an attribute version mark is introduced to realize efficient revocation of old attributes, thereby further improving the security of the scheme.

[0024] Embodiment one The embodiment provides an attribute-based encryption method supporting multi-authority accountability and outsourcing computing, please refer to Figure 1 , which comprises the following steps: S1: a central authorization institution is initialized to generate system public parameters, a master key, a user identity and an attribute authority institution identity, and an attribute authority institution is initialized to generate an attribute public key set and an attribute private key set; S2: the attribute authority institution generates a key corresponding to an attribute set submitted by a user based on the system public parameters, the attribute set submitted by the user and the attribute private key set; S3: a cloud server generates outsourcing encryption ciphertext based on the system public parameters, a data owner verifies the outsourcing encryption ciphertext by calling a smart contract based on the system public parameters, and then locally encrypts to-be-encrypted plaintext based on the system public parameters, the outsourcing encryption ciphertext, an access strategy, an attribute domain and the attribute public key set to obtain data ciphertext encrypted by the access strategy; S4: the cloud server locally updates the access strategy and the ciphertext according to a minimum change increment set uploaded by the data owner; S5: a data accessor decrypts the locally updated ciphertext and the data ciphertext based on the system public parameters and the user attribute key to obtain plaintext.

[0025] Specifically, S1 can be implemented by the central authorization institution running a system initialization algorithm, and the attribute authority institution running an attribute authority initialization algorithm. (1) System initialization algorithm Input security parameters Output global parameters (public parameters) Master key User identity pool And authority identity pool The specific steps are as follows: Generate bilinear group parameters: select cyclic group And , order prime , generator , bilinear mapping ; Randomly select Generate master key: randomly select , calculate , , Define system attribute domain (e.g. ), and generate initial version number for each attribute value . Select two hash functions: (used for user identity mapping) and (for ciphertext verification). Finally output: , , and initialize user identity pool And authority identity pool .

[0026] (2) Attribute authority initialization algorithm: Input global parameters And the attribute set managed by the authority , output public key And private key . The specific steps are as follows: randomly select as the authority private key component; for each attribute , randomly select , calculate the public key component: . Then set , . Finally, write to the blockchain smart contract for public storage.

[0027] S2 is key generation, which can be realized by Key generation algorithm: Input global parameters , user identity , attribute set A set of authoritative private keys with relevant attributes and timestamp Output user key The specific steps are as follows: The user submits an application to the authority that manages their attributes. Submit attribute set . Validate attribute validity; terminate if failure occurs. Calculate. For each attribute Extract attribute values and version number ,calculate Generate intermediate key (in From ).Then Synthesize the final key: randomly selected ,calculate , , , (Used to retract updates). Output user key. Accountability Design: Will Stored on the blockchain.

[0028] S3 is a data encryption solution that includes outsourced encryption, encryption structure verification, and local encryption by the data owner.

[0029] Outsourced encryption can be achieved through cloud servers. Running outsourced encryption algorithms To achieve: Input global parameters Output intermediate ciphertext The specific steps are as follows: Randomly select Basic computing components: , .right arrive (Outsourcing pool size), randomly selected , , ,calculate , , , , Output intermediate ciphertext (outer encrypted ciphertext). .

[0030] The encryption result can be verified by the data owner. Invoke the smart contract to execute the outsourced cryptographic verification algorithm accomplish: Input intermediate ciphertext and ciphertext , output verification result . The specific steps are as follows: randomly select . Calculate . Verify the equation: whether it is true, if the equation is true, output 1 (verification passed), otherwise output 0 (failed).

[0031] The data owner locally encrypts the data owner's local encryption algorithm to achieve: Input global parameters , plaintext , access policy , intermediate ciphertext and related attribute public key , output ciphertext and verification tag . The specific steps are as follows: define the access policy , where is a matrix, map the matrix row to the attribute name, is the attribute value. Hide the attribute value: replace the real attribute value in with a random value . Calculate the secret sharing: randomly select , let the vector , calculate . Construct the ciphertext , for to , calculate , . Generate the verification tag for verifying the correct generation of . Output the data ciphertext .

[0032] S4 is the policy update, which can be executed by the data owner to change the policy attribute algorithm: to achieve: Input the original attribute mapping function , ciphertext and related public key , output new mapping function and updated ciphertext . The specific steps are as follows: the data owner sends the new mapping function to . For each affected attribute , calculate , generate new ciphertext , where For the old ciphertext component in the policy update S4 by CSP or DO Recalculating the new ciphertext, For For the attribute One of the maintained private key components. This process only needs Complexity ( For the number of changed attributes.

[0033] The data owner DO performs Where The original attribute mapping function, The ciphertext generated after encrypting the access policy plaintext composed of the original attributes, The key related to the original attribute. The data owner will change the attribute mapping function To , define the original public key as , and the DO calculates the local update ciphertext The cloud server local update ciphertext Is .

[0034] S5 is data decryption, including: The data requester generates an outsourcing decryption key and a user decryption key based on the system public parameter and the user attribute key; The data requester obtains a form-modified ciphertext based on the locally updated ciphertext and the user decryption key; The data requester generates a partial decryption ciphertext decrypted by the cloud server in advance according to the system public parameter, the form-modified ciphertext, and the outsourcing decryption key; The data requester calls the smart contract to verify the partial decryption ciphertext and obtains a verification result; The data requester decrypts the data ciphertext based on the partial decryption ciphertext and the user decryption key to obtain the decrypted plaintext.

[0035] Specifically, data decryption includes conversion key generation, ciphertext modification, outsourcing decryption ciphertext generation, partial decryption ciphertext verification, and user local decryption.

[0036] In the specific implementation process, the conversion key generation is performed by the data requester By generating a conversion key algorithm: To achieve: Input the user key , output the conversion key And the recovery key . The specific steps are as follows: randomly select . Calculate the conversion key component: for each attribute , , ; ; . Output , , , , , is a component of the conversion key.

[0037] Outsourcing decryption algorithm (executed by CSP) . Input ciphertext and conversion key , output partial decryption ciphertext . The specific steps are as follows: parse the access policy . Find the minimum authorized set and constant satisfy . Calculate the partial decryption result , .

[0038] Partial decryption ciphertext verification can be implemented by the data requester executing the partial decryption ciphertext verification algorithm: : Input partial decryption ciphertext , verification tag and recovery key , output verification result . The specific steps are as follows: calculate and compare with . If , output 1 (verification passed), otherwise output 0 (failed).

[0039] User local decryption can be implemented by the data requester executing the user local decryption algorithm: : Input ciphertext , partial decryption ciphertext and recovery key , output plaintext . The specific steps are as follows: calculate .

[0040] The method further comprises revoking the attribute of the old version by using the version marking technology.

[0041] It can be implemented by an attribute revocation algorithm.

[0042] . Input the attribute to be revoked and the new version number , execute attribute revocation. The specific steps are as follows: Generate a new version number . Compute the conversion vector . Update ciphertext: for each ciphertext component containing the attribute, compute . AA generates user update key: . Unrevoked user update key: where is the ciphertext component obtained by the CSP in the revocation phase by multiplying the existing or with the version fix factor is the first component of the user attribute private key, is the revoked user's component of after update, is the exponent of multiplying .

[0043] The method further comprises S6: using a white-box tracking technique to bind the user identity and attribute key to track malicious users and malicious attribute authorities.

[0044] In the implementation process, S6 implements a malicious user tracking algorithm by the authorized institution: to achieve: Input suspicious user key , output user identity or . The specific steps are as follows: verify the key structure: for each attribute , check whether the following equation is true:

[0045]

[0046] If all the equations are true, it means that the verification is passed, and is output, otherwise is output.

[0047] When the system has key abuse, any authorized institution can track the specific identity of the malicious user. The authorized institution first checks whether the user attribute key meets the above construction form. If it does not meet, the algorithm outputs ⊥, giving up tracking the invalid attribute key; otherwise, continue the following key integrity checking process, if the integrity check fails, also output ⊥, giving up tracking the invalid attribute key; otherwise, output the unique identity of the user in the system .

[0048] Authority accountability algorithm Input suspicious user key , output authority identity or The specific steps are as follows: extracting the suspicious user key Querying in the blockchain The corresponding If it exists, output and revoke the authority, otherwise output , The attribute authority identifier recovered from the suspicious user key.

[0049] Embodiment two Based on the same inventive concept, the present embodiment provides an attribute-based encryption system supporting multi-authority accountability and outsourcing computation, please refer to Figure 2 , comprising: The system initialization module 101 is used for central authority initialization, generating system public parameters, user identity and attribute authority identity, attribute authority initialization, generating attribute public key set and attribute private key set; The key generation module 102 is used for attribute authority to generate a key corresponding to the attribute set submitted by the user based on the system public parameters, the attribute set submitted by the user and the attribute private key set; The data encryption module 103 is used for the cloud server to generate an outsourcing encryption ciphertext based on the system public parameters, and the data owner to verify the outsourcing encryption ciphertext based on the system public parameters, and then to locally encrypt the to-be-encrypted plaintext based on the system public parameters, the outsourcing encryption ciphertext, the access policy, the attribute domain and the attribute public key set, to obtain the data ciphertext encrypted by the access policy; The strategy updating module 104 is used for the cloud server to update the access policy and the ciphertext locally according to the minimum change increment set uploaded by the data owner; The data decryption module 105 is used for the data requester to decrypt the locally updated ciphertext and the data ciphertext based on the system public parameters and the user attribute key, to obtain the plaintext.

[0050] In one embodiment, the system further comprises a malicious user tracking module 106 for binding the user identity and the attribute key to track the malicious user and the malicious attribute authority by using the white-box tracking technology.

[0051] Specifically, please refer to Figure 3 The attribute-based encryption system supporting dynamic authorization and outsourcing computation based on blockchain provided by the present application comprises a central authority CA, an attribute authority AA, a data owner DO, a data requester DR, a cloud server CSP and a blockchain.

[0052] 1. Center Authority (CA): As the core trusted authority in the system, CA is responsible for receiving the registration applications of attribute authorities and users, and issuing unique identity identifiers in the system. However, CA does not directly participate in the attribute management or key generation process of the system.

[0053] 2. Attribute Authorities (AAs): AAs are a group of independent authorities that are responsible for distributing and managing user attribute information and providing more secure identity-based attribute keys for users. Each AA operates independently to ensure the privacy and security of user attributes.

[0054] 3. Cloud Service Provider (CSP): CSP provides ciphertext storage services for Data Owners (DOs) and assists terminal users with limited computing capabilities in completing part of the encryption or decryption tasks to reduce the local computing burden.

[0055] 4. Blockchain (BC): BC is used to store the verification information of the ciphertext, and the built-in smart contract is run through the network nodes to ensure the credibility of the CSP calculation results. This mechanism provides decentralized verification support for the system.

[0056] 5. Data Owner (DO): DO is responsible for formulating data access policies and encrypting data to be shared. When the computing resources of DO are limited, part of the encryption tasks can be outsourced to CSP, and the encryption results of CSP can be verified through the invocation of smart contract to ensure data security.

[0057] 6. Data Requester (DR): DR is responsible for decrypting the ciphertext and recovering the plaintext information. In the decryption process, DR with insufficient computing power can outsource most of the decryption tasks to CSP, and the decryption results of CSP can be verified through the smart contract to ensure the integrity and credibility of the data.

[0058] Since the system of the second embodiment of the present application is the system adopted for implementing the method of the first embodiment of the present application, the specific structure and variations of the system can be understood based on the method introduced in the first embodiment of the present application, and therefore will not be described here. Any system adopted by the method in the first embodiment of the present application belongs to the scope of protection of the present application.

[0059] Those skilled in the art will appreciate that embodiments of the present application can be readily used as a method, a system or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer-readable program code.

[0060] The present application is described in reference to the flowchart and / or block diagrams of the method, apparatus (system) and computer program product according to embodiments of the application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing element or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagrams. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagrams.

[0061] While the preferred embodiments of the application have been described, additional variations and modifications can be made to the embodiments by those skilled in the art once they learn of the basic inventive concepts. Therefore, the appended claims are intended to encompass within their scope all such variations and modifications as are included within the scope of the application. It should be apparent that the application is susceptible to various modifications and alternative forms evident to those skilled in the art without departing from the spirit and scope of the application. Accordingly, the application is intended to embrace all such alternatives, modifications and variations as fall within the scope of the claims, along with all equivalents thereof.

Claims

1. An attribute-based encryption method supporting multi-authoritative accountability and outsourced computation, characterized in that, include: The central authorized agency initializes the system, generating public parameters, master key, user identity, and attribute authorized agency identity. The attribute authorized agency initializes the system, generating attribute public key set and attribute private key set. The attribute authorization agency and the central authorization agency generate a key corresponding to the attribute set submitted by the user based on the publicly available parameters of the system, the attribute set submitted by the user, and the attribute private key set; The cloud server generates outsourced encrypted ciphertext based on publicly available system parameters. The data owner calls a smart contract based on publicly available system parameters to verify the outsourced encrypted ciphertext. Then, based on publicly available system parameters, outsourced encrypted ciphertext, access policy, attribute domain, and attribute public key set, the plaintext to be encrypted is locally encrypted to obtain the data ciphertext encrypted by the access policy. The cloud server performs partial updates to the access policy and ciphertext based on the minimum set of incremental changes uploaded by the data owner; Data access users can decrypt the partially updated ciphertext and data ciphertext based on system public parameters and user attribute keys to obtain the plaintext.

2. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 1, characterized in that, The attribute authorization authority and the central authorization authority generate attribute keys corresponding to the user-submitted attribute set based on the system's publicly available parameters, the user-submitted attribute set, and the attribute private key set, including: Users authorize attribute management authorities to manage their attributes. Submit attribute set; Validate attribute validity; terminate if failure occurs, otherwise calculate. ,in, H is the median value, and H is the hash function. For user identity, For timestamps; For each attribute , Extract attribute values and version number ,calculate Generate intermediate key ,in From attribute private key , The median value. and For common parameters, For attribute set; The centrally authorized agency synthesizes the final key, including: random selection. ,calculate , , , Output user key , ,in, , , , For elements in the user key, From the master key, It is a set of attributes.

3. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 1, characterized in that, The cloud server generates outsourced encrypted ciphertext based on publicly available system parameters, including: Cloud server randomly selected Basic computing components: , ,in, For the group, It is a bilinear mapping. For generators, From the master key, , Basic components; right arrive Random selection , , ,calculate , , , , ,in, , , , , As a component of the outsourced ciphertext, Size of the outsourced pool; Output outsourced encrypted ciphertext ; 。 4. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 3, characterized in that, The data owner invokes a smart contract based on publicly available system parameters to verify outsourced encrypted ciphertext, including: Randomly select a random number Perform the following calculations: in, and This is the batch factor for the outsourced encryption verification process. For the product aggregation term of the verification process; Verify the equation: Check if the equation is true. If the equation is true, the verification is successful; otherwise, the verification fails.

5. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 3, characterized in that, The data owner locally encrypts the plaintext to be encrypted based on publicly available system parameters, outsourced encrypted ciphertext, access policy, attribute fields, and attribute public key set, obtaining ciphertext encrypted by the access policy, including: Data owner defines access policy ,in for matrix, This is a mapping function used to map matrix rows to attribute names. For attribute values; Using random values replace The actual attribute values ​​in; Computational secret sharing includes: random selection ,vector ,calculate , The median value; Constructing ciphertext ,right arrive ,calculate , ,in, , , , As a component of encrypted data, For plain text, and for For attributes Maintained key parameters For DO in local encryption, for the first Random mask introduced by the row; Generate verification tags ; Output ciphertext .

6. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 1, characterized in that, Data access users decrypt the partially updated ciphertext and data ciphertext based on system public parameters and user attribute keys to obtain the plaintext, including: Data users generate outsourced decryption keys and user decryption keys based on system public parameters and user attribute keys; The data accessor obtains the modified ciphertext based on the partially updated ciphertext and the user's decryption key; Data users generate partially decrypted ciphertext pre-decrypted by the cloud server based on system public parameters, the modified ciphertext, and the outsourced decryption key. The data accessor invokes a smart contract to verify a portion of the decrypted ciphertext and obtains the verification result; Data access users decrypt the ciphertext based on a portion of the decrypted ciphertext and the user's decryption key to obtain the decrypted plaintext.

7. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 1, characterized in that, The method also includes: using version tagging technology to revoke the attributes of older versions.

8. The attribute-based encryption method supporting multi-authoritative accountability and outsourced computation as described in claim 1, characterized in that, The method also includes: using white-box tracking technology to bind user identity with attribute keys to track malicious users and malicious attribute authorities.

9. An attribute-based encryption system supporting multi-authoritative accountability and outsourced computation, characterized in that, include: The system initialization module is used by the central authorized agency to initialize the system, generate public system parameters, master key, user identity and attribute authorized agency identity, and attribute authorized agency to initialize the system, generate attribute public key set and attribute private key set. The key generation module is used by the attribute authorization authority to generate a key corresponding to the attribute set submitted by the user based on the system's public parameters, the attribute set submitted by the user, and the attribute private key set. The data encryption module is used by the cloud server to generate outsourced encrypted ciphertext based on publicly available system parameters. The data owner calls a smart contract based on publicly available system parameters to verify the outsourced encrypted ciphertext. Then, based on publicly available system parameters, outsourced encrypted ciphertext, access policy, attribute domain, and attribute public key set, the plaintext to be encrypted is locally encrypted to obtain the data ciphertext encrypted by the access policy. The policy update module is used by the cloud server to partially update the access policy and ciphertext based on the minimum set of change increments uploaded by the data owner. The data decryption module is used by data users to decrypt locally updated ciphertext and data ciphertext based on system public parameters and user attribute keys, obtaining plaintext.

10. The attribute-based encryption system supporting multi-authoritative accountability and outsourced computation as described in claim 9, characterized in that, The system also includes a malicious user tracking module, which uses white-box tracking technology to bind user identity with attribute keys to track malicious users and malicious attribute authorities.

Images