A privacy protection method for supervisable data flow conversion

Abstract

A kind of monitorable data flow transfer privacy protection method, including initialization phase: establishment center committee, user is registered in blockchain and center committee;Request negotiation phase: user and center committee negotiate service parameters;Agent service stage: user generates data fragment and conversion key, sends to center committee, carries out threshold agent re-encryption service, and the result is broadcasted on blockchain, and user receives own information and decrypts data;Supervision phase: center committee organizes regulatory agency to form consensus, and votes to decide whether to decrypt or not.This method uses ring signature and blockchain broadcast mode to break the link between data sender and data receiver, achieving privacy protection;Threshold agent re-encryption algorithm is used to protect the privacy of data and the mapping relationship between the two parties in the flow transfer process, and the informed consent and supervision power of the flow transfer process are distributed to multiple subjects by secret sharing, realizing fair supervision and access mechanism of seeking the consent of data owner.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of information security, and particularly relates to a supervisable data flow transfer privacy protection method. BACKGROUND

[0002] With the development of the times, data has become one of the core elements of the Internet ecological method. In the 2020 Opinion on Building a More Perfect Market-oriented Allocation Mechanism for Factors, the State Council proposed to accelerate the cultivation of data factor markets, study the establishment of effective data resource flow system norms, and formulate data privacy protection systems. In the Data Security Law and the Personal Information Protection Law, the audit and supervision of data transactions are emphasized, and higher compliance requirements are proposed for data flow transfer, and the similarities and differences between data subjects and data controllers are emphasized, as well as the personal consent and respect for the rights of individuals obtained by data processors in the processing process.

[0003] In the current data flow transfer scheme, the privacy of data has been well protected, but the privacy protection of the mapping relationship between the identities of the two parties in the flow transfer has not been emphasized, especially some flow transfer sharing schemes based on blockchain. Due to the characteristics of openness, transparency and non-tamperability of blockchain, attackers can analyze the global ledger and launch linkage attacks to analyze the mapping relationship between the identities of the two parties in the flow transfer and the flow transfer sharing mode. The exposure of the topology relationship of the user relationship poses a serious risk of privacy leakage.

[0004] At present, many data flow transfer privacy protection schemes use strong privacy protection strategies, which makes it impossible to monitor many illegal and criminal activities. Although some schemes consider monitoring while protecting privacy, the current monitoring mostly uses trusted and single-point monitoring methods. On the one hand, the expansion of the monitoring power of the monitoring party may infringe on the personal information and data privacy of the user, and may also result in unfair monitoring behavior. On the other hand, once the monitoring party is attacked by hackers, the user's privacy information may also be leaked.

[0005] In the Personal Information Protection Law passed on August 20, 2020, the similarities and differences between data subjects and data controllers are clarified, the rights of data subjects such as the right to know are clearly defined, and the obligation of data controllers to obtain the consent of data subjects in the data processing process is also clarified. In the current data flow transfer scheme, the sender and the receiver of the data are mostly considered as the roles of the scheme design, which does not meet the current compliance requirements. SUMMARY

[0006] In order to solve the problem of the balance between privacy and supervision in the existing data flow scheme, and the informed consent of the data subject in personal information protection, a privacy protection method of data flow is proposed, which can protect the privacy of data and the identity mapping relationship between the two parties in the flow, and apply the informed consent and supervision power of the flow process to multiple subjects by secret sharing, so as to realize the fair supervision and consent mechanism.

[0007] A kind of data flow privacy protection method of supervision, based on user, data subject, center committee composition data flow system, specifically includes the following steps:

[0008] Initialization phase: the establishment of center committee, user registration in blockchain and center committee;

[0009] Request negotiation phase: user and center committee negotiate service parameters, including user data flow request and response, and user and center committee service request and negotiation;

[0010] Proxy service stage: user generates data fragments and conversion key, sends to center committee, carries out threshold proxy re-encryption service, and broadcasts the result on the blockchain, and the user decrypts the data after receiving his own information in the broadcast;

[0011] Supervision stage: center committee organizes each regulatory agency to form consensus and vote to decide whether to decrypt.

[0012] Further, all users participating in data flow sharing are data collaborators, who are data senders or data receivers.

[0013] Further, the data subject is the data owner, that is, the person who has the right to own, use, benefit, transfer or dispose of the data.

[0014] Further, the center committee is composed of multiple independent regulatory agencies and data subjects, which provides threshold proxy re-encryption service, executes the consent mechanism of data processing, and supervises and traces the function.

[0015] Further, the registration of the user includes the following steps:

[0016] The user registers identity on the alliance chain through the certificate authority CA and joins the collaboration group; After successful registration, the user encrypts the data Data with the symmetric key K, uploads the data through the smart contract, and generates a data digest together, which describes the data source and data attribute; The center committee obtains the identity set and public key set of the alliance chain to form an identity database for subsequent identity authentication.

[0017] Further, the request negotiation phase includes the following steps:

[0018] Step 1: The user explicitly data collaboration needs by retrieving data abstract, negotiate and initiate the request to the user who holds the data at this time;

[0019] Step 2: The user who holds the data agrees to the request of the user who needs data, and agrees to initiate the re-encryption request to the central committee; the user who holds the data at this time is regarded as the data sender, and the user who needs data is regarded as the data receiver;

[0020] Step 3: The data sender takes the set Kset={Pk1, Pk2, …, Sk i , Pk n}, where Pk i is the public key of the user i in the collaboration ring group on the alliance chain, and Sk i is the private key of the data sender, generates a ring signature Rs based on this set, initiates a request to the center, negotiates re-encryption parameters (N, t) and signs with the ring signature Rs, where N is the number of institutions participating in the service, and t is the threshold of threshold secret sharing, that is, at least t institutions agree to the service, and threshold proxy re-encryption can be correctly executed;

[0021] Step 4: The central committee agrees to the negotiation result and returns an agreement response, and prepares to start the proxy service stage of threshold proxy re-encryption.

[0022] Further, the proxy service stage is as follows:

[0023] Step a: The data sender executes Encapsulate(Pk sender ), where Pk sender is the public key of the data sender, generates a re-encryption symmetric key K Re and an intermediate parameter capsule, and the data sender encrypts the data index Index D , the symmetric key K, its own identity identifier ID sender with the re-encryption symmetric key K Re , and the receiver identity identifier ID receiver to form a data packet DP, then executes Encrpt(DP,K Re ) to generate ciphertext C, then executes ReKeyGen(PK receiver , Sk sender , N, t) to generate conversion authorization Kfrags, where Pk receiver and Sk sender are the public key of the receiver and the private key of the sender respectively, then executes SecShare(DP,N,t) to generate data packet fragments Cfrags and IDfrags, packs (Kfrags, Cfrags, IDfrags) and signs with its own ring signature Rs, and sends it to the central committee together with the session identifier;

[0024] Step b: the center committee is composed of multiple sub-center committees, each of which is composed of different regulatory agencies and data subjects and performs different regulatory functions. After receiving (Kfrags, Cfrags, IDfrags), the center committee distributes (Kfrag i ,Cfrag i ,IDfrag i ) data pairs to sub-center committee i, which verifies the legitimacy and integrity of the data, and after agreeing, proxy re-encrypts the data pair to generate Cfrags and sends it to the center committee. After the center committee collects t Cfrags, C Re is recovered, uploaded to the blockchain and broadcast to the blockchain;

[0025] Step c: the data receiver continuously listens to the broadcast information, decrypts the information stream, and determines that the information belongs to himself when he listens to his public key information, and then searches for the data entity using the data index Index D , and then decrypts the data using the symmetric key K obtained by decryption.

[0026] Further, the regulatory stage includes the following steps:

[0027] Step I: a user or a regulatory agency believes that a certain data flow participates in illegal activities and requests the center committee;

[0028] Step II: the center committee accepts the request and requests each sub-center to request the secret information containing the identifier corresponding to the data flow;

[0029] Step III: the regulatory agency audits and verifies the data flow in the center committee, and discusses whether the transaction indeed participates in illegal criminal activities, and after forming a basic consensus, each agency votes on the consensus, that is, sends the corresponding identity fragments to the center committee;

[0030] Step IV: the center committee receives the responses of the regulatory members, and if a majority of the regulatory members believe that the address is illegal, the center committee calculates the original user identifier ID sender ←Recover(IDfrags,N,t), find the identity identifier of the data receiver, further find the data sender, and completely reveal the relevant information of the flow.

[0031] The beneficial effects of the present application are: (1) on the basis of providing basic data privacy protection, the mapping relationship of the identities of the two parties in data flow is also provided; (2) seeking a balance between privacy protection and regulatory traceability, providing a traceable way under the premise of protecting privacy, and not relying on a trusted, single-point central committee; (3) with the help of multiple relatively independent regulatory agencies to decentralize regulatory power, and on this basis, introducing a data flow consent mechanism to effectively protect the rights of data subjects. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flowchart of the data flow privacy protection method in the embodiment of the present application.

[0033] Figure 2 is a data message format diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be further described in detail below in conjunction with the drawings of the specification.

[0035] A regulatable data flow privacy protection method, specifically comprising the following steps:

[0036] The initialization stage is the establishment stage and the registration stage. The establishment stage mainly includes the establishment of the central committee, which involves multiple regulatory departments and data subjects. The registration stage mainly includes user registration through CA in the alliance chain, and user registration with the central committee.

[0037] The establishment stage is the establishment of the central committee. It is assumed that there are multiple departments that implement different ways of supervision on different aspects for a data flow process. Different regulatory departments and data subject representatives form different deputy central committees, and the central committee is a collection of these deputy central committees.

[0038] The registration stage is that the user and the central committee register digital certificates through a certificate authority (CA), and then join the alliance chain network through the authentication of a membership service provider. All users will be registered as a peer node at the time of registration. After registration, the user uses a symmetric key K, and encrypts the data with this symmetric key to generate Data enc , uploads and writes to the ledger, and attaches the data digest and description Digest. The central committee is registered as an order node. Then the user sends his digital certificate to the central committee for registration, and the central committee finally forms a member library of this alliance chain network.

[0039] The request negotiation stage is divided into user data flow request and response, and user service request and negotiation with the central committee.

[0040] Step 1: User B retrieves the account book, finds the data summary that meets the needs, sends a data flow request to A, and negotiates specific compensation, usage rights, etc.

[0041] Step 2: User A receives the message from user B, sends an agreement or disagreement to B, and if agreed, enters step 3. If not, return a rejection message and end the process.

[0042] Step 3: User A data sender takes the set Kset = {Pk1, Pk2, …, Sk i , Pk n}, where Pk i is the public key of the cooperative ring group user i on the alliance chain, and Sk i is the private key of the data sender. Based on this set, generate ring signature Rs and initiate a request message to the central committee to negotiate re-encryption parameters (N, t) and sign with ring signature Rs, where N is the number of deputy centers participating in the service, and t is the threshold of threshold secret sharing, that is, at least t deputy centers agree to service.

[0043] Step 4: The central committee agrees to the negotiation parameters and returns a session process identifier signed with its own private key, and prepares to start proxy re-encryption service, entering the proxy service stage. In the following process, user A is referred to as the data sender, and user B is referred to as the data receiver.

[0044] After the negotiation stage, enter the proxy service stage:

[0045] Step a: The data sender executes Encapsulate(Pk sender ), where Pk sender is the public key of the sender, generating re-encryption symmetric key K Re and intermediate parameter capsule. The data sender encrypts data index Index D , symmetric key K, its own identity identifier ID sender with re-encryption symmetric key K Re , and receiver identity identifier ID receiver to form data packet DP, then executes Encrpt(DP, K Re ) to generate ciphertext C, and then executes ReKeyGen(PK receiver , Sk sender , N, t) to generate conversion authorization Kfrags, where (Pk receiver and Sk senderRespectively, the public key of the receiver and the private key of the sender, then execute SecShare(DP, N, t) to generate data message fragments Cfrags and IDfrags, package (Kfrags, DPfrags, Cfrags) and send to the central committee with the session identifier and the ring signature Rs of the sender.

[0046] Step b: After receiving (Kfrags, DPfrags, IDfrags), the central committee verifies the ring signature, and after the ring signature verification is successful, it assigns the deputy central committee i to obtain (Kfrags i ,DPfrags i ,IDfrags i ) data pair, and the deputy central committee verifies the legitimacy and integrity of the data source, and after agreeing, it performs proxy re-encryption on the data pair to generate Cfrags and sends it to the central committee. After the central committee collects t Cfrags, it packages to generate C Re , uploads C Re to the blockchain, and broadcasts in the blockchain.

[0047] Step c: User B checks the information in the ledger, decrypts it with his own private key, and when he sees his own public key, he determines that the information belongs to himself, then executes Decrypt(Sk receiver ,C Re ) to generate K Re , then uses K Re to decrypt, gets the data index Index D , indexes to data Data enc , then uses the decrypted symmetric key K to decrypt and gets the data Data.

[0048] Supervision stage:

[0049] Step I: User B believes that a certain session identifier involves illegal activities in the flow and participates in illegal activities, and submits his own views to the central committee.

[0050] Step II: The central committee accepts the request and requests each deputy center for secret information containing the identifier corresponding to the data flow.

[0051] Step III: The supervisory agency conducts audit and verification of the data flow in the central committee, and discusses whether the transaction indeed participates in illegal criminal activities, and after forming a basic consensus, each agency votes on the consensus, that is, sends the corresponding identity fragments to the central committee.

[0052] Step IV: The central committee receives the response of the regulatory members, and if the majority of the regulatory members believe that the address is illegal, the central committee calculates the original user identifier ISsender Recover(IDfrags, N, t), find the identity identifier of the data receiver, further find the data sender, and fully reveal the relevant information of the flow.

[0053] The function realized by the method mainly lies in:

[0054] (1) Protection of data privacy: the data sender uploads the encrypted data to the blockchain. Assuming that the key is secure, the data cannot be decrypted without the consent of the data sender; in proxy re-encryption, the proxy cannot obtain the information of the transformed ciphertext as an intermediary for information transmission, and only responsible for transforming the ciphertext information, protecting the privacy and security of the data.

[0055] (2) Privacy protection of the mapping relationship between the data flow parties: in proxy re-encryption, it is usually assumed that the proxy is a curious third party. In the method, the central committee is a specific manifestation of the proxy, which is composed of government regulatory agencies, and provides proxy services in order to play a regulatory role. Under this assumption, the link relationship between the user flow is in an exposed state. In order to protect the privacy of the mapping relationship: the data sender requests the proxy when requesting services using ring signature, which is generated by the private key of other members in the alliance chain and the data sender. The central committee can easily verify that the member comes from a member on the alliance chain, but cannot confirm the specific identity; when the central committee completes the ciphertext conversion, the output information is not sent to the corresponding data receiver, because the central committee does not know the identity of the data receiver, and the output information flow of all converted ciphertexts is checked by the data receiver to see if it belongs to himself, and if it belongs to his data, it is intercepted for further decryption.

[0056] (3) Supervisable traceability of data flow: due to the protection of data privacy and the privacy of the mapping relationship between the data flow parties, the central committee cannot know the data content and the mapping relationship between the data flow parties. In order to provide supervision, the idea of secret sharing is used to achieve a certain degree of supervision without violating privacy. The data package of the data sender contains the plaintext of the identity identifier of the data receiver, but the identity identifier is secret shared to multiple regulatory agencies. Assuming that these regulatory agencies are fair and honest, under legal circumstances, any single regulatory agency cannot recover the identity of the receiver, but when the data flow is identified as illegal, the regulatory agencies will quickly reach a consensus and recover the identity identifier after a certain number of regulatory agencies consider it illegal.

[0057] (4) Data flow consent mechanism: This method introduces a data flow consent mechanism. In the current data flow scheme, the distinction between data holders and data owners is not considered. This method fully considers this relationship and introduces a data owner representative mechanism in the proxy, which means that the data owner's consent is required before the data can be transferred.

[0058] This method also has the following prevention strategies against possible attacks:

[0059] (1) Man-in-the-middle attack: This method can resist man-in-the-middle (MITM) attacks. MITM attacks provide fake public keys to users through a certificate authority (CA), which usually leads to sensitive information being decrypted. In this method, the blockchain acts as a CA, and the user's public key is placed in the published block. The data is distributed among the participating nodes and linked to the previous and next blocks. This makes the public key immutable, making it more difficult for attackers to publish false keys. In addition, since the blockchain is a distributed method, there is no single point of failure.

[0060] (2) Data tampering: This method can well protect the integrity of the data and prevent tampering. Assume that the hash function cannot be broken, because if the hash function can be broken and changed, there is no way to ensure that the data has not been tampered with. This method is based on the blockchain, which allows each user to publish the hash value of the data. Although an attacker may destroy the storage location and tamper with the data, he cannot change the hash value stored on the blockchain, which will make everyone know that the data has been tampered with.

[0061] (3) Replay attack: This method can resist replay attacks. The threshold proxy re-encryption algorithm will stamp the data with a timestamp when it enters the proxy processing stage. The central committee will analyze the timestamp of the data and verify the reasonable range of the timestamp.

[0062] (4) collusion attack: In the general proxy re-encryption scheme, collusion attack refers to the collusion between the proxy and the data recipient user B to try to calculate Rk A→B +Sk B →Sk A , where Rk A→B is the re-encryption key of user A to user B, SK B is the private key of user B, and SK A is the private key of the data sender. However, in this method, the proxy is not a single point. The threshold multi-point proxy greatly improves the difficulty of collusion attacks.

[0063] The above merely describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments, but any equivalent modifications or changes made by those skilled in the art according to the disclosed content of the present application shall be included in the protection scope recorded in the claims.

Claims

1. A method for privacy protection of a governable data flow, characterized in that: the method is based on a data flow system composed of users, data subjects and a central committee, and specifically comprises the following steps: In the initialization stage, the central committee is established, and the users are registered on the blockchain and the central committee; In the request negotiation stage, the user and the central committee negotiate service parameters, including the request and response of the user data flow, and the service request and negotiation between the user and the central committee; In the proxy service stage, the user generates data fragments and conversion keys, sends them to the central committee, performs threshold proxy re-encryption service, and broadcasts the results on the blockchain. After receiving his own information, the user decrypts the data; The proxy service stage is divided into the following steps: All users sharing data in the data flow are data collaborators, who are either data senders or data receivers. Step a: Data sender performs Encapsulate(Pk sender ), where Pk sender is the public key of the data sender, generates a re-encryption symmetric key K Re and an intermediate parameter capsule, the data sender encrypts the data index Index D , the symmetric key K, its own identity identifier ID sender with the re-encryption symmetric key K Re , and the receiver identity identifier ID receiver to form a data packet DP, then performs Encrpt(DP, K Re ) to generate ciphertext C, then performs ReKeyGen(Pk receiver , Sk sender , N, t) to generate a conversion authorization Kfrags, where Pk receiver and SK sender are the public key and the private key of the receiver respectively, then performs SecShare(DP, N, t) to generate data packet fragments Cfrags and IDfrags, packs (Kfrags, Cfrags, IDfrages) and signs with its own ring signature Rs, and sends it to the central committee together with the session identifier; Step b: the center committee is composed of multiple sub-center committees, each of which is composed of different regulatory agencies and data subjects and performs different regulatory functions; after receiving (Kfrags, Cfrags, IDfrags), the center committee is assigned to the sub-center committee i, obtains (Kfrag i ,Cfrag i ,IDfrag i ) data pairs, the sub-center committee verifies the legitimacy and integrity of the data, and after agreeing, the data pair is proxy re-encrypted to generate Cfrags and sent to the center committee. After the center committee collects t Cfrags, C Re is restored, uploaded to the blockchain and broadcast to the blockchain; Step c: the data receiver continuously listens to the broadcast information, decrypts the information stream, and determines that the information belongs to itself when its public key information is listened to, and then uses the data index Index D Search for the data body, and then decrypt the data using the symmetric key K obtained by decryption; supervision stage: the central committee organizes each supervision agency to form a consensus and vote to decide whether to decrypt. 2.The method of claim 1, wherein: The data subject is the data owner, that is, the person who has the right to own, use, benefit, transfer or dispose of the data. 3.The method of claim 1, wherein: The central committee is composed of multiple independent regulatory agencies and data subjects, providing threshold proxy re-encryption services, implementing data processing consent mechanisms, and monitoring and tracing functions.

4. The method of claim 1, wherein: User registration includes the following steps:

5. The method of claim 1, wherein: The user registers his identity on the alliance chain through the certificate authority CA and joins the collaboration group; after successful registration, the user encrypts the data Data with the symmetric key K, uploads the data through the smart contract, and generates a data digest that describes the data source and data attribute; the central committee obtains the identity set and public key set of the alliance chain to form an identity database for subsequent identity authentication. The request negotiation stage includes the following steps:

6. The method of claim 1, wherein: Step 1: The user clearly understands the data collaboration needs by searching the data digest, negotiates with the user holding the data, and initiates the request; Step 2: The user holding the data agrees to the request of the data user and agrees to initiate the re-encryption request to the central committee; at this time, the user holding the data is considered as the data sender, and the data user is considered as the data receiver; Step 4: The central committee agrees to the negotiation result and returns the agreement response, preparing to start the proxy service stage of threshold proxy re-encryption. Step 3: The data sender takes the set Kset = {PK1, PK2, …, SK i , …, Pk n}, wherein Pk i is the public key of the cooperative ring group user i on the alliance chain, and Sk i is the private key of the data sender, generates a ring signature Rs based on the set, initiates a request to the center, negotiates re-encryption parameters (N, t) and signs with the ring signature Rs, wherein N is the number of institutions participating in the service, and t is the threshold of threshold secret sharing, that is, at least t institutions agree to the service, and threshold proxy re-encryption can be correctly executed; The supervision stage includes the following steps:

7. The method of claim 1, wherein: Step I: A user or a regulatory agency believes that a certain data flow is involved in illegal activities and requests the central committee; Step II: The central committee accepts the request and requests the corresponding secret information containing the identifier from each deputy center for the data flow; Step III: The regulatory agencies audit and verify the data flow in the central committee and discuss whether the transaction is indeed involved in illegal criminal activities. After forming a basic consensus, each agency votes on the consensus, that is, sends the corresponding identity fragments to the central committee; ​ Step IV: The center committee receives the reply from the regulatory members, if the majority of the regulatory members think that the address is indeed illegal, the center committee calculates the original user identifier iD using these fragment information sender ← Recpver(IDfrags, N, t), find the identity identifier of the data receiver, further find the data sender, and fully reveal the relevant information of the flow.

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