Blockchain-enabled medical iot multi-keyword searchable encryption method

Abstract

The application discloses a kind of blockchain-enabled medical internet of things multi-keyword searchable encryption methods, first initialize a distributed blockchain system, system public parameter is placed in initial block;Blockchain node generates system public key through Pedersen secret sharing protocol;Cloud server initialization, generates a pair of keys and public key is disclosed;Data collector generates index according to keyword set, and sends to blockchain record data integrity, finally index is stored in cloud server;Data user sends the keyword set that wants to search to blockchain, and generates search trapdoor by calling trapdoor generation contract, and blockchain sends search trapdoor to cloud server for keyword-based search;Cloud server returns the result of search to data user;When data appears integrity dispute, blockchain is responsible for auditing.

Description

Technical Field

[0001] This invention belongs to the field of information security technology, specifically relating to a blockchain-enabled multi-keyword searchable encryption method for the Internet of Things in healthcare. Background Technology

[0002] The intelligence of a smart healthcare system is not only reflected in its ability to provide care to patients anytime, anywhere, but also in the privacy and controlled sharing of medical data. The Internet of Medical Things (IoMT) aims to achieve these functions by benefiting from ubiquitous connectivity, smart IoT devices, and 5G communication technology. In smart wards, data generated by wearable and monitoring devices can be stored locally in the collector for real-time status monitoring and diagnosis. However, due to the limited storage resources of IoT devices, secure data storage and sharing typically rely on cloud servers.

[0003] However, for medical data with high privacy and security requirements, and for cloud servers that are not entirely trusted, a model of encryption before uploading is typically adopted. Encryption can indeed ensure the confidentiality of data, but encrypted data inevitably hinders effective data sharing. Even attribute-based encryption (ABE) can only achieve confidentiality and fine-grained access control simultaneously, but cannot achieve effective ciphertext search.

[0004] Furthermore, plaintext keyword searches are completely unacceptable for IoMT (Internet of Things) because medical data requires the prohibition of all possible privacy breaches, including those stemming from search keywords. Therefore, searchable encryption is well-suited for data sharing in this field. Since symmetric searchable encryption requires extremely complex key management, public-key encryption with keyword-based search (PEKS) is more suitable for multi-device IoT environments. However, PEKS only enables one-to-one sharing, which is still impractical for frequently accessed healthcare scenarios. For example, if n doctors want to access a patient's data, the data owner needs to encrypt the search index n times using the public keys of each of the n doctors, placing significant demands on storage and computing resources.

[0005] Furthermore, in current cloud-assisted IoMT, the power of cloud servers is too centralized, as they simultaneously control data storage, search, access control, and tracking. Due to some characteristics of blockchain, such as its distributed nature, traceability, and immutability, the application of blockchain in IoT or IoMT has attracted considerable attention. On the one hand, some blockchain-assisted IoMT solutions have been proposed for data tracking, access control, and fair payments. On the other hand, blockchain is being used for search, and some work has even combined it with PEKS. However, while all these efforts attempt to leverage the advantages of blockchain to enhance security or functionality, no work has yet fundamentally integrated blockchain and PEKS, making blockchain a part of PEKS.

[0006] In conclusion, designing a multi-user, efficient, secure, and searchable blockchain encryption scheme for the Internet of Things (IoT) in healthcare is both challenging and of practical value. Summary of the Invention

[0007] To address the aforementioned issues, this invention presents a blockchain-enabled multi-keyword encrypted search method. This method employs a searchable encryption primitive to protect the search index and prevent privacy leaks. Furthermore, the blockchain handles the generation of search trapdoors, enabling traditional one-to-one searchable encryption to one-to-many, while reducing the overhead for data users. Additionally, the blockchain stores the hash value of the data for subsequent integrity audits.

[0008] First, a distributed blockchain system is initialized, with public system parameters placed in the initial block. Blockchain nodes generate a public key using the Pedersen secret sharing protocol. The cloud server initializes, generates a key pair, and publishes the public key. The data collector generates an index based on a set of keywords and sends it to the blockchain to record data integrity. Finally, the index is stored on the cloud server. Data users send a set of keywords they want to search to the blockchain, invoke a trapdoor generation contract to generate a search trapdoor, and the blockchain sends the search trapdoor to the cloud server for keyword-based search. The cloud server returns the search results to the data user. When data integrity disputes arise, the blockchain is responsible for auditing.

[0009] To achieve the above objectives, the technical solution adopted by this invention is: a blockchain-enabled multi-keyword searchable encryption method for the Internet of Things in healthcare, comprising the following steps:

[0010] S1, System Initialization: This step consists of three sub-steps.

[0011] S11, Blockchain Initialization: Establish a distributed blockchain and place system parameters in the initial block; the expression for the system parameter PP is as follows:

[0012] PP=(G,G T,p,e,g,h,H,H′);

[0013] Among them, G and G T Let G be a multiplicative group of order p, g be a generator of G, h ∈ G be a random element, and e: G × G → G T It is a symmetric bilinear mapping; H, H′ are collision-resistant hash functions;

[0014] S12, Blockchain generates system public key: A system public key is generated based on the Pedersen secret sharing protocol and stored in the ledger, i.e., it is globally public; the system public key PK s The expression is as follows:

[0015]

[0016] Where i is the node label and k is the threshold value in the Pedersen protocol. The parameters are randomly selected by each node. The generated value, L(i), is a Lagrange interpolation;

[0017] S13, Cloud Server Initialization: The cloud server automatically generates a public-private key pair, and publishes the public key; the public-private key (PK)... c SK c The expression is as follows:

[0018]

[0019] S2, Index Generation: The data collector (data owner) extracts a set of keywords {kw} from the collected data. i} i∈[1,e] Then, a search index is generated based on this set of keywords; the expression for the search index IX = (R, {I}) is:

[0020] R = g r ,I i =e(H(kw) i ),(PK s ) r )·e(h r PK c );

[0021] Where e is the number of keywords in the keyword set, and r is the number of keywords from... The element is randomly selected from the data;

[0022] S3, Trapdoor Generation: Data users generate a set of hash values ​​{W} from keywords. i =H(kw) i ′ )} i∈[1,f]The data is sent to the blockchain, which then invokes the trapdoor generation contract to generate a search trapdoor; the expression for the search trapdoor TD = (T1, T2) is:

[0023]

[0024] Where f is the number of keywords in the keyword set, and t is the number of keywords from... The element is randomly selected from the data;

[0025] S4, Search: Upon receiving the search trap, the cloud server runs a search; the expression for the search formula is:

[0026]

[0027] Where R is part of the index,

[0028] S5, Data Integrity Audit: When data may have been tampered with, any participant can request an integrity audit from the blockchain. The blockchain audits the data integrity based on the hash value stored in the ledger, identifying those responsible for data tampering.

[0029] To achieve the above objectives, the present invention also adopts the following technical solution: a blockchain-enabled medical IoT multi-keyword searchable encrypted product, including a computer program, which, when executed by a processor, implements the steps of any of the methods described above.

[0030] Compared with the prior art, the technical advantages of the present invention are as follows:

[0031] (1) This invention uses permissioned blockchain to replace the traditional one-to-one public key search encryption to complete the generation of search trapdoors by users, which can realize secure one-to-many data sharing.

[0032] (2) The data upload process, hash value and data access process are all recorded in the blockchain, which can be used for subsequent integrity audit and accountability.

[0033] (3) The blockchain executes the Pedersen protocol, which generates search traps for data users in a threshold manner. This thresholding method enhances security and system robustness.

[0034] (4) The index and trapdoor mentioned in this invention both satisfy cryptographic indistinguishability, and the indistinguishability of trapdoor is an effective means of resisting offline keyword guessing attacks. Attached Figure Description

[0035] Figure 1 This is a system framework diagram of the method of the present invention;

[0036] Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0038] The symbols and their definitions in this scheme are shown in Table 1:

[0039] Table 1

[0040] symbol definition <![CDATA[PP,PK s ]]> System parameters, system public key <![CDATA[G,G T (p)]]> Multiplicative group of order p g Generators of group G h Parameters in the system public key e Symmetric bilinear mapping H,H′ Collision-resistant hash function <![CDATA[(PK c ,SK s )]]> Cloud server key pair IX = (R, {I}) Search Index <![CDATA[{kw i } i∈[1,e] ]]> Keyword set <![CDATA[{W i =H(kw i ′)} i∈[1,f] ]]> Hash value of a set of keywords <![CDATA[TD=(T1,T2)]]> Search trap

[0041] like Figure 1 As shown, the blockchain-enabled multi-keyword searchable encryption method for the Internet of Things in healthcare proposed in this invention includes four participants:

[0042] (1) Data Collector: A resource manager computer located near monitoring and wearable devices in the ward. It is assumed that these devices and the collector are situated on a secure wireless network, allowing the collector to securely collect data from these devices. The collector is responsible for generating an index based on keywords.

[0043] (2) Data users: For example, doctors can access patient data by requesting it from the blockchain. Assuming there is a way to authenticate the user and the blockchain, the user only needs to provide keywords for searching, without triggering trapdoor generation.

[0044] (3) Blockchain: Responsible for initializing the system and generating the system public key. At the same time, blockchain nodes jointly execute the Pedersen protocol threshold to generate trapdoors for data users.

[0045] (4) Cloud server: used to store indexes and perform searches.

[0046] Figure 2 The data interaction process of the entire solution is demonstrated, showcasing a blockchain-enabled multi-keyword searchable encryption method for the Internet of Things in healthcare. The specific implementation steps are described below:

[0047] Step S1, System Initialization: This consists of three sub-parts.

[0048] S11, Blockchain Initialization. Establishing a distributed blockchain and placing system parameters in the initial block includes the following steps:

[0049] (1.1.1) Based on the safety parameters, select two multiplicative cyclic groups G and G' of order p. TA bilinear pair e: G×G→G T g is a generator of group G, and h is an element randomly selected from G.

[0050] (1.1.2) Select two collision-resistant hash functions: H:{0,1} * →G,H′:G→G.

[0051] (1.1.3) Publicly disclose system parameters PP = (G, G T ,p,e,g,h,H,H′).

[0052] S12, the blockchain generates the system's public key. This includes the following steps:

[0053] (1.2.1) Each blockchain node calculates according to the Pedersen protocol. And broadcast

[0054] (1.2.2) Generate the system public key using Lagrange interpolation threshold method

[0055] (1.2.3) Store the system public key in a ledger, i.e., make it publicly available globally.

[0056] S13, Cloud Server Initialization. This includes the following steps:

[0057] (1.3.1) Cloud server randomly selected

[0058] (1.3.2) Calculate and publish PK c =g α .

[0059] Step S2, Index Generation. This includes the following steps:

[0060] (2.1) The data collector (data owner) extracts a set of keywords {kw} from the collected data. i} i∈[1,e] .

[0061] (2.2) From Randomly select element r and calculate R = g r ,I i =e(H(kw) i ),(PK s ) r )·e(h r PK c ).

[0062] (2.3) Send the index IX = (R, {I}) to the blockchain.

[0063] (2.4) The blockchain stores the uploaded data and data hashes, and then sends the search index to the cloud server for storage.

[0064] Step S3, trapdoor generation. This includes the following steps:

[0065] (3.1) Data users will use the hash value {W} of a set of keywords. i =H(kw) i ′ )} i∈[1,f] Send it to the blockchain.

[0066] (3.2) Blockchain call trapdoor generation contract generates search trapdoors. From Randomly select element t in the middle and calculate

[0067] (3.3) Send the search trapdoor TD = (T1, T2) to the cloud server.

[0068] Step S4, Cloud Server Search. This includes the following steps:

[0069] (4.1) Calculation

[0070] (4.2) Substitute into the formula Perform a search.

[0071] Step S5, Data Integrity Audit. When data may have been tampered with, any participant requests an integrity audit from the blockchain. The blockchain assesses data integrity based on the hash value stored in the ledger. If data has been modified, the responsible party for the tampering is identified through data upload and access records.

[0072] This invention addresses data security and privacy concerns in the context of the Internet of Things (IoT) in healthcare. It utilizes blockchain technology to improve upon traditional one-to-one public-key searchable encryption, designing a blockchain-enabled multi-keyword one-to-many encrypted search method. This method employs searchable encryption as a primitive to protect the search index and prevent privacy leaks. Furthermore, the blockchain handles the generation of search trapdoors, enabling one-to-many encryption instead of the traditional one-to-one searchable encryption, while reducing overhead for data users. Additionally, the blockchain stores the hash value of the data for subsequent integrity audits.

[0073] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A blockchain-enabled multi-keyword searchable encryption method for the Internet of Things in healthcare, characterized in that: Includes the following steps: S1, System Initialization: This step includes three sub-steps; S11, Blockchain Initialization: Establish a distributed blockchain and place system parameters in the initial block; the expression for the system parameter PP is as follows: in, and For the order is a large prime number The multiplicative group of g, where g is generator, It is a random element. It is a collision-resistant hash function; S12, Blockchain generates system public key: A system public key is generated based on the Pedersen secret sharing protocol and stored in the ledger, i.e., it is globally public; the system public key The expression is as follows: Where i is the node label and k is the threshold value in the Pedersen protocol. The parameters are randomly selected by each node. The generated value, It is a Lagrange interpolation; S13, Cloud Server Initialization: The cloud server automatically generates a public-private key pair, and publishes the public key; the public-private key... The expression is as follows: S2, Index Generation: The data collector (data owner) extracts a set of keywords from the collected data. Then, a search index is generated based on this set of keywords; the search index The expression for {I} is: ； Where e is the number of keywords in the keyword set. The element is randomly selected from the data; S3, Trapdoor Generation: Data users generate a set of hash values ​​for keywords. Send to the blockchain to invoke the trapdoor generation contract to generate a search trapdoor; the search trapdoor The expression is: Where f is the number of keywords in the keyword set. The element is randomly selected from the data; S4, Search: Upon receiving the search trap, the cloud server runs a search; the expression for the search formula is: Where R is part of the index, , / e( ,R); S5, Data Integrity Audit: When data may be tampered with, any participant can apply to the blockchain for an integrity audit; the blockchain audits the data integrity based on the hash value stored in the ledger and identifies the person responsible for the data tampering.

2. A blockchain-enabled medical IoT multi-keyword searchable encrypted product, comprising a computer program, characterized in that: When the computer program is executed by a processor, it implements the steps of the method as described in claim 1.

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