A ciphertext policy attribute-based access control method for smart medical care

Abstract

The present invention relates to the field of information security encryption technology, specifically to a ciphertext policy attribute-based access control method for smart medical care, comprising the following steps: an attribute authorization agency initializes parameters, publishes public parameters and retains a master key; a data user obtains an authorized attribute set and a corresponding private key; a data owner generates a real ciphertext and a test ciphertext and hides the attributes of the access policy, and transmits the real ciphertext, the test ciphertext and the access policy to a cloud service provider; the data user obtains the test ciphertext from the cloud service provider to perform an access rights test, and if the access policy is satisfied, the real ciphertext is decrypted by a private key. This scheme designs a row index obfuscated Bloom filter to support full hiding of ciphertext attribute policies. For smart medical scenarios, while avoiding access policy leakage, it can also protect the identity and attribute privacy of users in the scenario, thereby improving privacy protection of user identities.

Description

Technical Field

[0001] The present invention relates to the technical field of information security encryption, and in particular to a ciphertext policy attribute-based access control method for smart medical care. Background Art

[0002] With the rapid development of modern information and communication technology, the concept and technology of smart cities, which make cities more efficient and sustainable, have attracted the attention of various countries and governments. As an important part of smart cities, smart healthcare (SHC) has also been widely used in various cities due to its scientific, accurate and efficient modern medical service system.

[0003] However, in a cloud-assisted medical service environment, users' medical data faces a serious risk of being leaked. When users share their medical data stored in the cloud with medical institutions, doctors or experts, it may be illegally accessed, resulting in information leakage or trafficking. Especially in deep learning and service applications, the medical data uploaded by users to the cloud for medical diagnosis may be archived by the cloud, medical institutions or doctors, and then leaked. The leakage of users' medical data will not only seriously affect users' purchase of personal medical insurance, but also leak users' personal privacy information.

[0004] The commonly used encryption access control scheme is the Ciphertext Policy Attribute-based Encryption (CP-ABE), which grants users different access rights through their own attributes and can also encrypt data. It not only combines the advantages of data encryption and access policy technology, but also supports flexible and fine-grained access control policies. However, the current CP-ABE scheme mainly hides some policies. In this policy hiding scheme, an attribute is expressed using attribute names and attribute values. The attribute name is saved in plain text in the access policy, while the attribute value is hidden in the ciphertext. This allows users to infer the user's privacy information through the attribute name, which is very easy to leak the user's personal privacy information. Summary of the invention

[0005] The technical problem of the present invention is that the current ciphertext policy attribute-based scheme usually uses attribute name and attribute value to express an attribute, and the attribute name is saved in plain text in the access policy, while the attribute value is hidden in the ciphertext, which allows users to infer their privacy information through the attribute name.

[0006] The basic solution provided by the present invention is a ciphertext policy attribute-based access control method for smart medical care, which includes four entities, namely, the data owner, the cloud service provider, the attribute authorization agency and the data user, and includes the following steps:

[0007] S1: The attribute authority initializes parameters, publishes public parameters and retains the master key;

[0008] S2: The data user obtains the authorized attribute set and the corresponding private key;

[0009] S3: The data owner generates real ciphertext and test ciphertext and hides the attributes of the access policy, and transmits the real ciphertext, test ciphertext and access policy to the cloud service provider;

[0010] S4: The data user obtains the test ciphertext from the cloud service provider to test the access rights. If the access policy is met, the real ciphertext is decrypted by the private key. If the access policy is not met, the access is terminated.

[0011] Further, the S1 comprises the steps of:

[0012] S101: The attribute authority sets the global attribute space of the system make is the multiplicative cyclic group on prime numbers p, and obtains the bilinear map

[0013] S102: Let L RI To save the maximum bit length of the row index of the secret sharing value generator matrix, let L RIGBF is the length of RIGBF array, let k be the number of hash functions used in RIGBF;

[0014] S103: Randomly select a generator and From the multiplicative cyclic group Random selection Elements And determine k mappings of attribute values ​​from 0 to L RIGBF The hash functions at the -1 subscript are H1(·), H2(·), …, H k (·);

[0015] S104: Public parameter PK is published:

[0016]

[0017] In the formula, g is the group A generator in Y is obtained by bilinear mapping. An element on LRI The maximum bit length of the row index of the matrix to store the secret shared value, L RIGBF is the length of the RIGBF array, let k be the number of hash functions used in RIGBF, the hash functions H1(·), H2(·), …, H k (·) Map attribute values ​​from 0 to L RIGBF -1 subscript.

[0018] S105: Set the master secret key MSK to <g α >Retain.

[0019] Further, the S2 comprises the steps of:

[0020] S201: Data users collect data based on their own attributes Complete certification in the property authority;

[0021] S202: The attribute authorization agency calculates the following according to the user attribute set S:

[0022]

[0023] In the formula, Random selection;

[0024] S203: The private key SK on the attribute set S s = <K,L,{K x} x∈A >Sent to data users.

[0025] Further, generating the real ciphertext and the test ciphertext in S3 includes the following steps:

[0026] S301: Select two vectors Used to encrypt real ciphertext, Used to generate decryption test ciphertext;

[0027] S302: Calculation and Where i = 1,…,m, is an m×n secret sharing matrix, is the i-th row vector of the matrix;

[0028] S303: Randomly select m elements Calculate the real ciphertext CT and the test ciphertext CT respectively t :

[0029] CT=(C,C′,{C i ,D i} 1≤i≤m ),CT t =(Ct ,C′ t ,{Ct i} 1≤i≤m )

[0030] In the formula,

[0031]

[0032]

[0033] In the formula, CT is the real ciphertext, CT t is the generated test ciphertext.

[0034] Further, the attributes of the hidden access policy in S3 include the steps of:

[0035] S304: Remove access policy The mapping function ρ in ;

[0036] S305: Record the mapping relationship between the row number and the attribute by confusing the Bloom filter with the row index.

[0037] Furthermore, the transmission form of the real ciphertext, test ciphertext and access policy in S3 is:

[0038]

[0039] Further, the access permission test in S4 includes the steps of:

[0040] S401: Obtain the row index set S corresponding to the influencing attribute in RIGBF according to the attribute set S′ of the data user RI ={i|i=RIGBQuery(x)andi≤i≤m};

[0041] S402: Order S RI =(i1,i2,…,i I ), S S′ =(x1,x2,…,x I ), I=|S RI | is the set S RI The number of elements in the set S RI and the secret sharing matrix Get the matrix matrix The j-th row matrix The i j row, 1≤j≤I;

[0042] S403: According to Calculating vectors

[0043] S404: If the vector There is no solution, then the data user does not satisfy the access policy. If the vector If there is a solution, then calculate:

[0044]

[0045]

[0046] Judgment C t Are they equal to A / D? If not, it means that DU does not meet the access policy and ends the access; otherwise, continue with the subsequent steps.

[0047] Further, decrypting the real ciphertext in S4 includes the steps of:

[0048] S405: By vector and the data user's private key SK S′ Ciphertext Decrypt and calculate:

[0049]

[0050] In the formula, i j ∈S RI , x i ∈S S′ , calculate C / B to get the message

[0051] The principles and advantages of the present invention are:

[0052] 1. Compared with the existing ciphertext policy attribute-based encryption scheme, this scheme designs a row index confusion Bloom filter to support full hiding of ciphertext attribute policies. For smart medical scenarios, while avoiding access policy leakage, it can also protect the identity and attribute privacy of users in the scenario, thus achieving privacy protection of user identities.

[0053] 2. This scheme is based on the constructed prime order group and implements the decryption test of user attributes before the decryption step, thereby improving the efficiency of data access.

[0054] 3. In the scenario of medical data sharing, one of the main features is one-to-many. The same data may be shared by multiple users. The ciphertext policy attribute-based encryption scheme used in this solution is very consistent with the one-to-many feature. Only one authorization is required to allow users who meet the attribute access policy to have access rights, while other users do not have access rights. At the same time, the ciphertext policy attribute-based encryption scheme used in this solution has good support for access granularity. It grants fine-grained access authorization to users through their different identity attributes, which is very flexible and easy to expand.

[0055] 4. In the application scenario of secure data sharing in smart medical care, where data is frequently accessed by multiple users, this solution adds a decryption test before determining whether a user has access rights. This allows the user to be determined to have access rights without decrypting the actual ciphertext, thereby improving the overall access bandwidth and making access control more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The present invention is a flowchart of the steps of a ciphertext policy attribute-based access control method for smart medical care.

[0057] Figure 2 This is an entity framework diagram of a ciphertext policy attribute-based access control method for smart medical care according to the present invention. DETAILED DESCRIPTION

[0058] The following is further described in detail through specific implementation methods:

[0059] The specific implementation process is as follows:

[0060] Embodiment 1

[0061] Embodiment 1 is basically as shown in the attached Figure 1 As shown, a ciphertext policy attribute-based access control method for smart medical care includes the following steps:

[0062] S1: The attribute authority initializes parameters, publishes public parameters and retains the master key;

[0063] S2: The data user obtains the authorized attribute set and the corresponding private key;

[0064] S3: The data owner generates real ciphertext and test ciphertext and hides the attributes of the access policy, and transmits the real ciphertext, test ciphertext and access policy to the cloud service provider;

[0065] S4: The data user obtains the test ciphertext from the cloud service provider to test the access rights. If the access policy is met, the real ciphertext is decrypted by the private key. If the access policy is not met, the access is terminated.

[0066] like Figure 2 As shown, there are mainly four entities in this embodiment, namely: Data Owner (DO), Cloud Service Provider (CSP), Attribute Authority (AA) and Data Users (DU).

[0067] Among them, the data owner (patient) owns the medical data and uploads the encrypted medical data to the cloud according to the attribute access policy set by himself. Data users (doctors, nurses or experts) can only pass the access test and access the medical data of the data owner if they meet the access policy set by the data owner. The attribute authorization agency (certificate authority) is used to initialize the system parameters and authenticate the data owner and data user according to their attribute sets. After the authentication is passed, the private key corresponding to the attribute set is generated. Cloud service providers (Huawei Cloud, Tencent Cloud, etc.) mainly provide computing and storage services for users, which are used in the framework to save the ciphertext data of the data owner and the access requests of the corresponding data users.

[0068] This embodiment designs a row index garbled Bloom filter (RIGBF) to support full hiding of ciphertext attribute policies. For smart medical scenarios, while avoiding access policy leakage, it can also protect the identity and attribute privacy of users in the scenario, thereby achieving privacy protection of user identities.

[0069] Specifically, S1 includes the following steps:

[0070] S101: The attribute authority sets the global attribute space of the system make is the multiplicative cyclic group on prime numbers p, and obtains the bilinear map

[0071] S102: Let L RI To save the maximum bit length of the row index of the secret sharing value generator matrix, let L RIGBF is the length of RIGBF array, let k be the number of hash functions used in RIGBF;

[0072] S103: Randomly select a generator and From the multiplicative cyclic group Random selection Elements And determine k mappings of attribute values ​​from 0 to L RIGBF The hash functions at the -1 subscript are H1(·), H2(·), …, H k (·);

[0073] S104: Public parameter PK is published:

[0074]

[0075] In the formula, g is the group A generator in Y is obtained by bilinear mapping. An element on L RI The maximum bit length of the row index of the matrix to store the secret shared value, L RIGBF is the length of the RIGBF array, let k be the number of hash functions used in RIGBF, the hash functions H1(·), H2(·), …, H k (·) Map attribute values ​​from 0 to L RIGBF -1 subscript.

[0076] S105: Master key reserve.

[0077] S2 includes the steps:

[0078] S201: Data users collect data based on their own attributes Complete certification in the property authority;

[0079] S202: The attribute authorization agency calculates the following according to the user attribute set S:

[0080]

[0081] In the formula, Random selection;

[0082] S203: The private key SK on the attribute set S S = <K,L,{K x} x∈S >Sent to data users.

[0083] Generating real ciphertext and test ciphertext in S3 includes the following steps:

[0084] S301: Select two vectors Used to encrypt real ciphertext, Used to generate decryption test ciphertext;

[0085] S302: Calculation and Where i = 1,…,m, is an m×n secret sharing matrix, is the i-th row vector of the matrix;

[0086] S303: Randomly select m elements Calculate the real ciphertext CT and the test ciphertext CT respectively t :

[0087] CT=(C,C′,{C i ,D i} 1≤i≤m ),CT t =(C t,C′ t ,{Ct i} 1≤i≤m )

[0088] In the formula,

[0089]

[0090]

[0091] In the formula, CT is the real ciphertext, CT t is the generated test ciphertext.

[0092] The attributes of the hidden access policy in S3 include the following steps:

[0093] S304: Remove access policy The mapping function ρ in ;

[0094] S305: Record the mapping relationship between the row number and the attribute by confusing the Bloom filter with the row index.

[0095] Specifically, the specific implementation of hiding access policy attributes is shown in Algorithm 1:

[0096]

[0097] The transmission form of the real ciphertext, test ciphertext and access policy in S3 is:

[0098]

[0099] Access permission testing in S4 includes the following steps:

[0100] S401: Obtain the row index set S corresponding to the influencing attribute in RIGBF according to the attribute set S′ of the data user RI ={i|i=RIGBFQuery(x)andi≤i≤m}; The implementation of RIGBFQuery here is specifically shown in Algorithm 2:

[0101]

[0102]

[0103] S402: Order S RI =(i1,i2,…,i I ), S S′ =(x1,x2,…,x I ), I=|S RI | is the set S RI The number of elements in the set S RI and the secret sharing matrix Get the matrix matrix The j-th row matrix The i j row, 1≤j≤I;

[0104] S403: According to Calculating vectors

[0105] S404: If the vector There is no solution, then the data user does not satisfy the access policy. If the vector If there is a solution, then calculate:

[0106]

[0107]

[0108] Judgment C t Are they equal to A / D? If not, return ⊥ to indicate that DU does not meet the access policy and ends the access; otherwise, continue with the subsequent steps.

[0109] Decrypting the real ciphertext in S4 includes the following steps:

[0110] S405: By vector and the data user's private key SK s′ Ciphertext Decrypt and calculate:

[0111]

[0112] In the formula, i j ∈S RI , x i ∈S S′ , calculate C / B to get the message

[0113] In order to verify the accuracy of the full strategy hiding, decryption test and decryption process of this solution, this embodiment also provides the correct proof of decryption test and the proof of decryption correctness as follows.

[0114] Decryption test correctness proof: First, obtain the index set S on the attribute set of the data user through step S402 RI If the attribute set of the data user satisfies the access policy, and because the linear secret sharing strategy has the property of reconstruction, then there must be a vector that satisfies the following formula:

[0115]

[0116] in, and Then, calculate

[0117]

[0118] and

[0119]

[0120] Among them, K, L are the private keys of DU, i j ∈S RI ={r1,r2,…,r I}.make because Can get By transposing both sides of the equation, we can get According to the above formula, we have Right now Therefore, we can get Established.

[0121] Finally, if the attribute set of DU satisfies the hidden access policy, then Must be equal to

[0122]

[0123] Otherwise, it means that the attribute set of DU does not meet the attribute access policy set by DO and has no access rights.

[0124] Decryption correctness proof: According to

[0125]

[0126] It can be seen that:

[0127]

[0128] Because, RIGBFQuery(x j )=i j , we can get ρ(i j )=x j Therefore, from the above formula we can get

[0129]

[0130] Established. And because get Established, and then based on

[0131]

[0132] have Established.

[0133] Therefore, we can get Established, and then calculated Obtain the plaintext message. Proof completed.

[0134] The above are only embodiments of the present invention. Common knowledge such as the known specific structures and characteristics in the scheme is not described in detail here. Ordinary technicians in the relevant field know all the common technical knowledge in the technical field to which the invention belongs before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A ciphertext policy attribute-based access control method for smart medical care, including four entities: data owner, cloud service provider, attribute authorization agency and data user, characterized in that: S1: The attribute authority initializes parameters, publishes public parameters and retains the master key; S2: The data user obtains the authorized attribute set and the corresponding private key; S3: The data owner generates real ciphertext and test ciphertext and hides the attributes of the access policy, and transmits the real ciphertext, test ciphertext and access policy to the cloud service provider; S4: The data user obtains the test ciphertext from the cloud service provider to test the access rights. If the access policy is met, the real ciphertext is decrypted by the private key. If the access policy is not met, the access is terminated. The S1 comprises the steps of: S101: The attribute authority sets the global attribute space of the system make is the multiplicative cyclic group on prime numbers p, and obtains the bilinear map S102: Let L RI To save the maximum bit length of the row index of the secret sharing value generator matrix, let L RIGBF is the length of RIGBF array, let k be the number of hash functions used in RIGBF; S103: Randomly select a generator and From the multiplicative cyclic group Random selection Elements And determine k mappings of attribute values ​​from 0 to L RIGBF The hash functions at the -1 subscript are H1(·), H2(·), …, H k (·); S104: Public parameter PK is published: In the formula, g is the group A generator in Y is obtained by bilinear mapping. An element on L RI The maximum bit length of the row index of the matrix to store the secret shared value, L RIGBF is the length of the RIGBF array, let k be the number of hash functions used in RIGBF, the hash functions H1(·), H2(·), …, H k (·) Map attribute values ​​from 0 to L RIGBF -1 subscript; S105: Set the master secret key MSK to <g α >Retain.

2. According to claim 1, a ciphertext policy attribute-based access control method for smart medical care is characterized by: The S2 comprises the steps of: S201: Data users collect data based on their own attributes Complete certification in the property authority; S202: The attribute authorization agency calculates the following according to the user attribute set S: In the formula, Random selection; S203: The private key SK on the attribute set S S = <K,L,{K x } x∈S >Sent to data users.

3. According to claim 2, a ciphertext policy attribute-based access control method for smart medical care is characterized by: The steps of generating the real ciphertext and the test ciphertext in S3 include: S301: Select two vectors Used to encrypt real ciphertext, Used to generate decryption test ciphertext; S302: Calculation and Where i = 1,…,m, is an m×n secret sharing matrix, is the i-th row vector of the matrix; S303: Randomly select m elements Calculate the real ciphertext CT and the test ciphertext CT respectively t : CT=(C,C′,{C i ,D i } 1≤i≤m ),CT t =(C t ,C′ t ,{Ct i } 1≤i≤m ) In the formula, In the formula, CT is the real ciphertext, CT t is the generated test ciphertext.

4. According to claim 3, a ciphertext policy attribute-based access control method for smart medical care is characterized by: The attributes of the hidden access policy in S3 include the following steps: S304: Remove access policy The mapping function ρ in ; S305: Record the mapping relationship between the row number and the attribute by confusing the Bloom filter with the row index.

5. According to claim 4, a ciphertext policy attribute-based access control method for smart medical care is characterized by: The transmission form of the real ciphertext, test ciphertext and access policy in S3 is:

6. According to claim 5, a ciphertext policy attribute-based access control method for smart medical care is characterized by: The access permission test in S4 includes the following steps: S401: Obtain the row index set S corresponding to the influencing attribute in RIGBF according to the attribute set S′ of the data user RI ={i|i=RIGBFQuery(x)andi≤i≤m}; S402: Order S RI =(i1,i2,…,i I ), S S ′=(x1,x2,…,x I ), I=|S RI | is the set S RI The number of elements in the set S RI and the secret sharing matrix Get the matrix matrix The j-th row matrix The i j row, 1≤j≤I; S403: According to Calculating vectors S404: If the vector There is no solution, then the data user does not satisfy the access policy. If the vector If there is a solution, then calculate: Judgment C t Are they equal to A / D? If not, it means that DU does not meet the access policy and ends the access; otherwise, continue with the subsequent steps.

7. According to claim 6, a ciphertext policy attribute-based access control method for smart medical care is characterized by: Decrypting the real ciphertext in S4 includes the following steps: S405: By vector and the data user's private key SK S′ Ciphertext Decrypt and calculate: In the formula, i j ∈S RI , x i ∈S S′ , calculate C / B to get the message

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