The invention provides a method and system for privacy protection of block chain transaction. The method comprises: a transaction group is established between nodes of a block chain system, a user establishes an account at a node, and the node generates public and private key information of the account and then joining of a group is carried out; a transaction request node encrypts transaction information by using a broadcast encryption algorithm, carries out group signature processing on the encrypted transaction information, and then broadcasts the transaction information after broadcast encryption and group signature processing; a common non-account-recording node verifies the transaction information and then broadcasts the transaction information, an account-recording node decrypts thetransaction information and performs an intelligent contract to carry out account recording, broadcast encryption is carried out and then the information is recorded into a public account book, wherein the stored data are only allowed to be opened by the account-recording node, the transaction request node and an administration node. With the broadcast encryption algorithm and group signature technology, a privacy protection problem in the block chain system is solved and the traceability of the transaction is ensured.

Method and system for privacy protection of block chain transaction

The invention discloses a data sharing method and system, a blockchain system, and computing equipment. The data sharing method comprises the following steps: after receiving data from a data owner, a data storer stores the data and submits basic information of the data to the blockchain system; when receiving an access request from a user, the data storer judges whether the user sending the access request has an access authority or not according to the basic information stored in the blockchain system and the access authority of the user for the data; and if the user has the access authority for the data for which the access request is sent, the data storer provides the data to the user according to the access authority. The data sharing method and system, the blockchain system and the computing equipment adopting the technical scheme have the advantages that costs and resource input can be greatly reduced, and global sharing control for the data can be achieved.

Data sharing method and system, blockchain system, and computing equipment

The invention belongs to the technical field of information retrieval and database structure, discloses a method for storing and sharing secure files based on a blockchain, and uses the blockchain technology to realize secure storage and sharing of files. A user encrypts and uploads the files to obtain a file pointer, and acquires the partial file as the excitation after the accounting node writesthe information such as the formulated access policy and the pointer into a blockchain account. And the other users may acquire a file key from the adjacent accounting node or the file owner after satisfying the access policy to decrypt the files so as to finally obtain a plaintext file. The invention ensures the security of the user data, and is simple and convenient for the user to use, and thepublic key cryptography technology makes the file more secure at the same time. The unchangeable modification progress of the blockchain account further ensures the complete availability of the files, enables the user to formulate different access strategies for different files, and enables full control of the files while sharing the same.

Method for storing and sharing secure files based on blockchain

The invention relates to a supervisory blockchain system and method. The system comprises a certificate authority (CA), a key distribution center (KDC), a supervision department and a common node, wherein the CA performs identity authentication for the common node to generate registration information about the node, and the registration information is opened to a blockchain network and waits to be written into a blockchain to complete the registration of the node; the KDC prepares supervision rules, defines a complete attribute set of the supervision department, and distributes keys to the supervision department according to specific attributes of the supervision department; the supervision department acquires the keys from the KDC, monitors network transactions of the blockchain, and adopts the own keys to decrypt the node registration information in the blockchain and acquire the real identity of the node when an abnormal account occurs; and the common node interacts with the CA, performs identity authentication, and joins the blockchain to operate after completing the registration. According to the system and method disclosed by the invention, a supervisory blockchain is constructed by using ABE, signatures and other cryptography techniques, different supervision departments are allowed to supervise data of the blockchain system according to different functions, and thus the occurrence of illegal acts and the like can be prevented.

Supervisory blockchain system and method

The invention discloses a zero knowledge proving method suitable for protecting the privacy of a block chain, and a medium. UTXO of Bitcoins and a balance model of Ethereum can be supported, and wellcombined with a smart contract, so that the security of the scheme can be further enhanced, the application scene of the scheme can be extended, and aiming at a zero knowledge certificate designed bya specific algebraic structure of a transaction, even a light node can also generate a proving process. The technical scheme is as follows: the method comprises a system parameter in an initializationphase (including a generation process and meaning of the parameter), a specific process of generating the zero knowledge certificate in a certificate generating phase (including ciphertext generatedin the process, and involved formula and parameter), and a verification phase (including verification formula and condition).

Zero knowledge proving method suitable for protecting privacy of block chain, and medium

The invention discloses a block chain privacy data access control method based on attribute encryption, which mainly solves a problem in the prior art that the real identity of a user in the block chain is anonymously protected but the and transaction privacy information is not encrypted so as to cause privacy leakage. The method comprises the steps that 1. a system is initialized; 1, a user registers to obtain attribute information; 3, an authoritative center, according to the user attribute information, distributes a user private key; 4 a transaction party encrypts transaction privacy data and uploads the transaction privacy data to a block chain; 5, an accountant verifies the transaction information and performs the transaction; 6, a supervisory center is authorized to use the authorized private key to decrypt and check the transaction ciphertext. The method encrypts the transaction privacy information, avoids the leakage of data privacy and can be used for privacy protection of the virtual asset transaction data in the block chain.

Block chain privacy data access control method based on attribute encryption

The invention discloses a message-based and key-dependent privacy data encryption method. The method mainly solves the problems of key-related attacks and key exposure accidents due to the neglected consideration of the correlation between plaintexts and keys and the E-mail-based distribution of group public keys in the prior art. The method comprises the flowing steps: 1, initializing system parameters by an authorization center; 2, verifying the identity of a user at the authorization center; 3, distributing a key to the user who passes the identity authorization; 4, obtaining a cipher text through processing a plaintext file based on the obtained key by the user; 5, uploading the cipher text to a cloud server by the user; 6, during usage, requiring to download the cipher text from the cloud server by the user, obtaining and decrypting the cipher text after the cloud sever passes the request of the user. According to the technical scheme of the invention, the security encryption of a block-chain wallet file is realized through the message-based and key-dependent encryption method in the single-user mode, so that the key exposure is avoided. The occurrence of key-related attacks is reduced, and the safety of the wallet file is improved.

Message-based and key-dependent privacy data encryption method

The invention discloses an intelligent medical service method based on undistinguishable confusion, which is characterized in that a data owner independently decides allocation for the medical data access authority through carrying out security symmetric encryption on medical information uploaded to a cloud server; a medical data analysis mechanism carries out confusion on a medical data analysis program by using an undistinguishable confusion technology, the confused program is deployed to the cloud server, and security analysis is carried out on the medical data by using a confusion program so as to acquire a correct medical analysis result; and the access authority of other related mechanisms for a ciphertext can be controlled conveniently without changing the ciphertext structure by using a key sharing scheme. According to the invention, the privacy of data is realized, interaction of keys is reduced, and storage and management of a great number of keys are avoided; the integrity and the effectiveness of data can be verified; and the access type of medical data is decided by the user, the overall structure of an algorithm is not change at the same time, and the expansibility of the scheme is enhanced.

Intelligent medical service method based on undistinguishable confusion

The invention discloses a privacy protection method of an unmanned automobile, which mainly solves the problem of privacy leakage caused by the fact that participant identity information is not hiddenand the problem of single point failure of a centralized server in the prior art; the method comprises the following implementation steps: 1, a system is initialized and public parameters are generated; 2, participants in a network generate respective public keys and private keys; 3, the system dynamically divides nodes in the network into clusters; 4, a software service provider uploads a driveupdate package to cloud storage; 5, the software service provider generates a transaction and sends the transaction to the cluster head; 6, the cluster head and an automobile manufacturer verify the drive update package; 7, the cluster head broadcasts the transaction with successful verification, and a new block is generated and connected to a block chain; 8, the unmanned automobile obtains the drive update package according to the new block information and carries out update. According to the method, reliable privacy protection is provided for the participants, malicious participants are prevented from tampering with messages, and safety of the system is improved.

Privacy protection method of unmanned automobile

The invention discloses a homomorphic encryption-based virtual asset anonymous ranking method. The main objective of the invention is to solve the problems of user privacy disclosure and the narrow range of single-client ciphertext ranking which are caused by a condition that a private key is directly handed over to a proxy server in the prior art. The implementation process of the method includes the following steps that: 1) a system is initialized, and the signature public and private key and some public parameters of an authorization center (CA) are determined; 2) a user carries out identity registration application in the authorization center (CA); 3) the authorization center (CA) issue a key to the registered user; 4) the user uses his or her own key to participate in asset ranking and directly encrypts his or her asset data through a learning with error (LWE)-based homomorphic encryption algorithm, and ciphertexts are processed, the ranking of virtual assets is realized. With the method of the invention adopted, the protection of the privacy of the user can be realized, and the universality and anti-conspiracy attack ability of ciphertext ranking can be improved. The method can be used for asset supervision in a bitcoin network.

Wang Yuxiao

Papers

Block chain privacy data access control method based on attribute encryption

Message-based and key-dependent privacy data encryption method

Intelligent medical service method based on undistinguishable confusion

Privacy protection method of unmanned automobile

Homomorphic encryption-based virtual asset anonymous ranking method