CN109740364A - The cipher text searching method based on attribute of controllable search permission - Google Patents

Abstract

The cipher text searching method based on attribute of controllable search permission, belongs to and can search for field of encryption, and solution must not carry out sharing problem to search permission, and S5. re-encrypted private key generates: input common parameter, private key, access structure obtain re-encrypted private key；S6. re-encryption ciphertext generates: input common parameter, initial ciphertext and re-encrypted private key, Cloud Server export re-encryption ciphertext；S7. cipher text searching: former ciphertext and data owner's token are inputted, cipher text searching algorithm is executed；S8. re-encryption cipher text searching: input re-encryption ciphertext and data consumer's token execute cipher text searching algorithm, and effect is that retrieval and decryption distinguish so that designing more flexible easy to operate.

Description

The cipher text searching method based on attribute of controllable search permission

Technical field

The invention belongs to can search for field of encryption, it is related to a kind of cipher text searching side based on attribute of controllable search permission Method.

Background technique

With the rapid development of cloud computing technology and big data, cloud storage mode significantly reduce local datastore and Management cost realizes the application service of high quality, therefore more and more by the favor of enterprises and individuals user.Because cloud takes Data on business device are not perfectly safe, usually need to be to ciphertext data are stored in Cloud Server again after data encryption, this Although way solves the safety problem of data, but encrypted data searching ciphertext and search access control become a difficulty Topic.

For that can limit user's decryption capabilities while guaranteeing data confidentiality again, attribute base encrypts (Attribute-Based Encryption, ABE) method be suggested.Communication pattern based on encryption attribute scheme is one-to-many, guarantee data secret Property while, it is flexible, convenient to have the characteristics that, can effectively reduce the expense in data encryption process, well protect user it is hidden It is private.With going deep into for research, two kinds can be divided into according to ciphertext or the difference of cipher key associated attribute based on the encipherment scheme of attribute Form: the attribute base encryption of key strategy and the attribute base of Ciphertext policy encrypt.On the basis of encryption attribute, document is proposed Ciphertext policy based on attribute can search for encryption (Ciphertext-Policy Atrribute based Searchable Encryption, CP-ABSE) scheme, but the research achievement of document shows that key is in no any processing in CP-ABS scheme In the case of be directly uploaded to Cloud Server and can cause the unsafe problems such as Key Exposure, and using tree-like access structure efficiency compared with It is low.

1998, BLAZE M et al. proposed the concept of proxy re-encryption (ProxyRe-encryption, PRE), In PRE, authorized person generates a proxy re-encrypted private key to succedaneum based on the private key of oneself, and succedaneum utilizes re-encrypted private key The ciphertext of donor is converted into the ciphertext for licensee, and succedaneum can not obtain in plain text, also can not according to again plus The private key of key acquisition donor.2014, document will can search for encipherment scheme and proxy re-encryption technology phase based on attribute In conjunction with proposing a kind of proxy re-encryption for supporting to can search for function, in the case where meeting condition, the program can be by itself Search capability is assigned to succedaneum, executes searching ciphertext by succedaneum and operates.2015, Liang et al. proposed a kind of based on KP- ABE's can search for encipherment scheme.The program supports keyword to update, and recall precision with higher, and in random oracle mould The safety of scheme is demonstrated under type.But the encryption attribute of key strategy is used, the setting of access strategy can only rely on authorization Center.

Summary of the invention

In view of the above-mentioned problems, the present invention proposes a kind of cipher text searching method based on attribute of controllable search permission, including Following steps:

S1. system is established, and obtains common parameter and main private key；

S2. key generates: inputting the attribute set and main private key of user, obtains the private key for user of corresponding attribute set；

S3. ciphertext generates: input access structure, common parameter, main private key and keyword, data owner execute algorithm and produce Raw original ciphertext；

S4. threshold generation: input common parameter, private key and keyword to be checked, data owner generate the order of keyword Board；

S5. re-encrypted private key generates: input common parameter, private key, access structure obtain re-encrypted private key；

S6. re-encryption ciphertext generates: input common parameter, initial ciphertext and re-encrypted private key, and Cloud Server output adds again Ciphertext；

S7. cipher text searching: former ciphertext and data owner's token are inputted, cipher text searching algorithm is executed；

S8. re-encryption cipher text searching: input re-encryption ciphertext and data consumer's token execute cipher text searching algorithm.

Further, the step of system is established, and obtains common parameter and main private key is as follows:

System is established setup (N, n): the maximum number of column n of the attribute total number N and access control matrix M of input system, raw At a 4- multilinear pairing: { e_i:G₀×G_i→G_i+1| i=0,1,2 }, wherein (G₀,...,G₃) it is that the plain rank that rank is p recycles Group, enables g₀∈G₀, g₀It is G₀Generation member, and for i=0,1,2, g_i+1=e_i(g₀,g₁) it is G_i+1Generation member, take h_1,1, h_1,2,...,h_n,N∈G₀, define hash function H:{ 0,1 } and * → G₀, randomly select Expression integer set 0, 1 ..., p-1 }, then common parameter is and main private key are as follows:

Msk=(a, b) (2).

Further, the step of key generates is as follows:

Key generates keyGen (msk, S): inputting the attribute set S and main private key msk of user, randomly selects index t₁,...t_n←Z_P, Z_PIndicate the set of integer { 0,1 ..., p-1 }, ifX ∈ S is taken,The raw private key of the user of corresponding attribute set S are as follows:

Sk=(D, { L_j}j∈[1,n],{D_x}x∈S) (3)。

Further, the step of ciphertext generates is as follows:

Ciphertext generate Enc (kw, pp, msk, (M, ρ)): input access structure (M, ρ), common parameter pp, main private key msk and Keyword kw ∈ { 0,1 }^*, data owner executes the algorithm and generates former ciphertext, and the line number and column of matrix M are respectively indicated with l and n Number, is associated with attribute for the every a line of access structure, and defining the mapping function is ρ, and calculating randomly selects n-1 random element and choosing Select s ← Z_PVector is formed as shared secretFor i ∈ { 1,2 ..., l }, takeWith J ∈ { 1 ..., n } is calculated

And obtain ciphertext:

Cph=((M, ρ), A_i,j,B,C_i,C₁,C₂)_{i∈[1,l],j∈[1,n]} (4)。

Further, threshold generation TokenGen (pp, sk, kw): input common parameter pp, private key sk and key to be checked Word kw calculates separately T for i ∈ { 1,2 ..., l }₁=e₀(H (kw), D), T_j=e₀(H(kw),L_j), T_x=e₀(H(kw),D_x)x ∈ S, then data owner generates the token of keyword kw are as follows:

Token=(S, T₁,{T_j}_j∈[1,n],{T_x}_∈S) (5)。

Further, re-encrypted private key generate ReKeyGen (pp, sk, (M ', ρ ')): input common parameter pp, private key sk, Access structure (M ', ρ ') respectively indicates the line number and columns of matrix M ' with l and n, and the every a line of access structure is associated with attribute, Defining the mapping function is ρ ', randomly selects n-1 element and composition vectors immediatelyFor i ' ∈ { 1,2 ..., l }, takesWith j ' ∈ { 1 ..., n }, calculate

Export re-encrypted private key are as follows:

rk_(M′,ρ′)=(B ', { A '_i,j}_{i∈[1,l],j∈[1,n]}) (6)。

Further, re-encryption ciphertext generates ReEnc (cph, pp, rk_(M′,ρ′)): input common parameter pp, initial ciphertext Cph=(C₁,C₂) and re-encrypted private key rk_(M′,ρ′), calculateCloud Server exports re-encryption ciphertext are as follows:

cph^R=((M ', ρ '), C '₁,C′₂,B′,{A_i,j}_{i∈[1,l],j∈[1,n]}) (7)。

Further, cipher text searching Search (token, cph): input original ciphertext cph and data owner's token Token executes cipher text searching algorithm, and whether verifying user property collection S meets access structure P=(M, ρ), if it is satisfied, then one Surely set c can be obtained in polynomial time_i, which meets ∑_ρ(i)∈Sc_i·λ_i=(1,0 ..., 0), then it calculates

IfIt then proves to search for successfully, otherwise search failure.

Further, re-encryption cipher text searching Search^R(token^R,cph^R): input re-encryption ciphertext cph^RAnd data User token token executes cipher text searching algorithm, and whether verifying user property collection S meets access structure P=(M ', ρ '), such as Fruit meets, then set c ' can be centainly obtained in polynomial time_i, which meets ∑_ρ′(i)∈Sc′_i·λ′_i=(1, 0 ..., 0), then calculate

If e₂(K′,C′₁)=C '₂, then prove to search for successfully, otherwise search failure.

The utility model has the advantages that controllable search is realized using the encryption attribute mode that can search for based on Ciphertext policy, in conjunction with agency's weight The mode of encryption shares search permission.Extract the keyword fragment in ciphertext to form search token in scheme, retrieval and Decryption distinguishes so that designing more flexible easy to operate.The mode used for the linear sharing matrix of LSSS, visit by fine granularity control Search efficiency is improved while asking.New departure can carry out fine-grained control to search permission while guaranteeing data security System.

Detailed description of the invention

Fig. 1 system model figure.

Specific embodiment

1 basic conception explanation

1.1 bilinear map

Define 1 bilinear map.G and G_TIt is the multiplicative cyclic group that two ranks are p.Bilinear map e:G × G → G_T, g, g_T Respectively G, G_TGeneration member, while meet with following property:

Bilinearity: there are e (g^a,g^b)=e (g, g)^ab, wherein

Non-degeneracy: there are g ∈ G, so that e (g, g) ≠ 1.

Computability: rightE (u, v) can be calculated effectively.

1.2 difficulty problems are assumed

The definition of n- multilinear pairing: the prime number p of given security parameter l and a l bit, n- multilinear pairing is by n A p rank group (G₀,G₁,...,G_n-1) and n-1 mapping e_i:G₀×G_i→G_i+1(i=0 ... n-2) composition.N- multilinear pairing is answered Property under the satisfaction, for (i=0 ... n-2):

If g ∈ G₀For G₀Generation member, then g_i+1=e_i(g₀,g_i) it is G_i+1Generation member.

·Meet

·e_iIt can effectively calculate.

N- polyteny Decisional Diffie-Hellman assumption (n-Mut-ilinear Decisional Diffie- Hellman Assumption, n-MDDH) selectionG is the generation member of G.Given g^a,g^b,g^s,g^z, do not deposit Z=e (g, g) can be distinguished in probabilistic polynomial time algorithm with the advantage that can not ignore^absWith Z=e (g, g)^z, wherein algorithm Advantage be defined as | Pr [Α (g^a,g^b,g^s,e(g,g)^abs)=1]-Pr [Α (g^a,g^b,g^s,e(g,g)^z)=1] |.

2 scheme models

2.1 system model

The system model that the present invention uses by taking medical cloud scene as an example as shown in Figure 1, illustrate: model includes four realities Body is authorization center, Cloud Server, data owner Alice and search user Bob respectively.Of the data owner Alice oneself It is uploaded to cloud after people's medical data and data key words encryption, subsequent search operaqtion can be divided into two kinds of situations, first is that working as her Attending physician Bob when needing to check case, condition can be set to C₁The access conditions of={ attending physician }, and retrieval is enabled Board and Cloud Server is sent it to, commission Cloud Server completes searching ciphertext；Second is that attending physician needs to check her disease When example inquires into the state of an illness with other doctor Carol, Alice, which can need to formulate according to oneself access strategy such as doctor, need to meet C₂= The condition of { attending physician Bob, doctor Carol } generates re-encrypted private key and is sent to Cloud Server, and commission Cloud Server will The permission of search key is shared with the data consumer for meeting access conditions.In this model, authorization center is responsible for management and is belonged to Property collection, and be generated for user according to property set and distribution is corresponding private key.Cloud Server is responsible for the data of storage encryption, is to use Family provides cipher text searching service and uses re-encrypted private key, and grantee is allowed to carry out keyword to the ciphertext of re-encryption Retrieval.In whole process, data grant person completes not online and in the case where not interacting with authorized user, and search is weighed Limit is shared with other users.

3 algorithms are realized

The specific implementation of 3.1 schemes

System is established setup (N, n): the maximum number of column n of the attribute total number N and access control matrix M of input system, raw At a 4- multilinear pairing: { e_i:G₀×G_i→G_i+1| i=0,1,2 }, wherein (G₀,...,G₃) it is that the plain rank that rank is p recycles Group.Enable g₀∈G₀It is G₀Generation member, and for i=0,1,2, g_i+1=e_i(g₀,g₁) it is G_i+1Generation member.Take h_1,1, h_1,2,...,h_n,N∈G₀, define hash function H:{ 0,1 }^*→G₀.It randomly selectsExpression integer set 0, 1 ..., p-1 } all subsets, choose element a, b, c uniformly randomly from set, then common parameter is and main private key are as follows:

Msk=(a, b) (11)

Key generates keyGen (msk, S): inputting the attribute set S and main private key msk of user.Randomly select index t₁,...t_n←Z_P, indicate that the set of integer { 0,1 ..., p-1 }, the meaning of this formula are that n are randomly selected in set at random Number, ifX ∈ S is taken,The raw private of the user of corresponding attribute set S Key are as follows:

Sk=(D, { L_j}j∈[1,n],{D_x}x∈S) (12)

Ciphertext generate Enc (kw, pp, msk, (M, ρ)): input access structure (M, ρ), common parameter pp, main private key msk and Keyword kw ∈ { 0,1 }^*, data owner executes the algorithm and generates former ciphertext.The line number and column of matrix M are respectively indicated with l and n Number, is associated with attribute for the every a line of access structure, and defining the mapping function is ρ.Calculating randomly selects n-1 random element and choosing Select s ← Z_PVector is formed as shared secretFor i ∈ { 1,2 ..., l }, takeAnd j ∈ { 1 ..., n } is calculated Need specification: H indicates hash function, is a kind of operation.H (kw) indicates to carry out Hash operation to kw.

By above-mentioned, ciphertext is obtained:

Cph=((M, ρ), A_i,j,B,C_i,C₁,C₂)_{i∈[1,l],j∈[1,n]} (13)。

Threshold generation TokenGen (pp, sk, kw): input common parameter pp, private key sk and keyword kw to be checked, for I ∈ 1,2 ..., and l } calculate separately T₁=e₀(H (kw), D), T_j=e₀(H(kw),L_j), T_x=e₀(H(kw),D_x) x ∈ S, then it counts The token of keyword kw is generated according to owner are as follows:

Token=(S, T₁,{T_j}_j∈[1,n],{T_x}_∈S) (14)

Re-encrypted private key generates ReKeyGen (pp, sk, (M ', ρ ')): input common parameter pp, private key sk, access structure (M′,ρ′).The every a line of access structure is associated with attribute, defines this and reflect by the line number and columns that matrix M ' is respectively indicated with l and n Penetrating function is ρ '.Randomly select n-1 element and composition vectors immediatelyFor i ' ∈ 1, 2 ..., l }, it takesWith j ' ∈ { 1 ..., n }, calculate Export re-encrypted private key are as follows:

rk_(M′,ρ′)=(B ', { A '_i,j}_{i∈[1,l],j∈[1,n]}) (15)

Re-encryption ciphertext generates ReEnc (cph, pp, rk_(M′,ρ′)): input common parameter pp, initial ciphertext cph=(C₁, C₂) and re-encrypted private key rk_(M′,ρ′).It calculatesCloud Server exports re-encryption ciphertext are as follows:

cph^R=((M ', ρ '), C '₁,C′₂,B′,{A_i,j}_{i∈[1,l],j∈[1,n]}) (16)

Cipher text searching Search (token, cph): input original ciphertext cph and data owner token token executes close Literary searching algorithm.Whether verifying user property collection S meets access structure P=(M, ρ), if it is satisfied, then centainly can be multinomial Set c is obtained in the formula time_i, which meets ∑_ρ(i)∈Sc_i·λ_i=(1,0 ..., 0), then it calculates

IfIt then proves to search for successfully, output 1, otherwise search failure, output 0.

Re-encryption cipher text searching Search^R(token^R,cph^R): input re-encryption ciphertext cph^RAnd data consumer's token Token executes cipher text searching algorithm.

Whether verifying user property collection S meets access structure P=(M ', ρ '), if it is satisfied, then centainly can be in multinomial Set c ' is obtained in time_i, which meets ∑_ρ′(i)∈Sc′_i·λ′_i=(1,0 ..., 0), then calculate

If e₂(K′,C′₁)=C '₂, then prove to search for successfully, output 1, otherwise search failure, output 0.

3.2 correctness

Search key verification of correctness:

If property set S meets access structure (M, ρ), and re-encryption ciphertext is corresponding crucial identical, then

Therefore available:

Search key verification of correctness after re-encryption:

Therefore available:

4 Security Proofs

4.1 data confidentiality

If 1 4-MDDH problem of theorem is difficult to resolve, CP-ABRKS scheme is under random oracle model can not area Divide property selection keyword attack safety.

Prove that assuming that there are a probabilistic polynomial time opponent A breaks through the random of CP-ABRK with the advantage ε that can not ignore Indistinguishability selection keyword attacks safe game under oracle model, then a challenger can be constructed can not neglect Probability slightlySolve the problems, such as 4-MDDH, wherein q_TIt is the maximum times of opponent's inquiry response devices.

The example that challenger C gives a 4-MDDH problemWhereinW is from setIn random number, simulation as follows:

Initialization: opponent A selects a challenge access structure (M^*,ρ^*) wherein M^*For l^*×k^*Matrix, l^*For line number, k^* For columns, and send them to challenger.Assuming that attribute total number is N, access control matrix M in system^*Maximum number of column For n_max, challenger generates common parameter and main private key as follows:

(1) access structure (M is given^*,ρ^*), for every a pair of (j, x), wherein 1≤x≤N, 1≤j≤n_max, selectionMake ρ if there is an i^*(i)=x and i≤k^*, then enable It is the i row j column of matrix； Otherwise it enablesIf common parameter are as follows:

Main private key is mk=(a, b).

(2) challenger analog answer device H as follows

O_H(kw): a keyword kw is given, simulator works as follows:

If kw was not queried, takeAnd with probability P r [c_i=0]=1/ (q_T+ 1) a bit c is selected_i∈ {0,1}.If c_i=0, it calculatesOtherwise it calculates(kw, a_i,H(kw),c_i) be added Table L_HIn and return to H (kw).Otherwise, from L_HIn retrieve H (kw) corresponding with kw and return H (kw).

Stage 1:A can carry out the inquiry of multinomial time or less transponder:

(a)O_keyGen(S) given attribute collection S, challenger work as follows:

If S meets access structure, return ⊥ (end mark).

Otherwise, if S is unsatisfactory for access structure (M^*,ρ^*), then there is a vector The set for indicating n times vector operation in integer { 0,1 ..., p-1 }, so that w₁=-1 and For k^* ≤ j≤n is setIt calculatesRandom selectionAnd impliedly define t_j=r_j+w_jB, then for each x ∈ S, setting makes if there is iOtherwise it sets

(b)O_rk(S, P): one property set S of input and an access structure P=(M, ρ), wherein M is the matrix of l × k, is chosen War person works as follows:

L_rkIt is re-encryption list, if L_rkRecord is not present in table, returns to ⊥.Else if record exists, then random choosing Take n index and composition vectorIf Otherwise, vector is formed IfWherein define s=cs '.

(c)O_ReEnc(S, cph): a given property set S and former ciphertext cph, challenger work as follows:

If L_rkIn table it is existing record or when P ≠ P^*, O is inquired with (S, P)_rkObtain re-encrypted private key rk_uid→P, and count Calculate cph^R←Re Enc(cph,pp,rk_P).It can be regarded as the combination that property set and access structure are constituted.

Otherwise, if in such as middle L_HThere are kw_i, so that c_i=1 andSelect d ∈ Z_PIf And for every a pair of i=1 ... N, and j=1 ... nReturn to cph^R=(C₁,C′₂,B,{R_{i,j}i∈[1,l],j∈[1,n]})。

Otherwise, mistake occurs and stops.

(d)O_token(S, kw): a given property set S and a keyword kw, challenger work as follows:

O is inquired with kw_HObtain (a_i,H(kw),c_i)。

If c_i=1, selectionIt calculatesL′_j=e₀(H(kw),L_j)j∈[1, n]；And for each x ∈ S,

If c_i=0 and access structure is not met, inquires O with S_keyGenSk is obtained for j=1 ... n calculates D ', L '_j、Mode is same as above.

Otherwise, it generates mistake and stops.

Challenge: A two isometric keyword (kw₀,kw₁).If c₀=1 and c₁=0, if η=1；Work as c₀=0 and c₁=1, So set η=0；If c₀=1 ∧ c₁=1, challenger generates mistake and stops；Otherwise, it randomly chooses

Challenger will use kw_ηInquiry obtains ciphertextReturn to A.

Stage 2: increase limitation (kw₀, kw₁) O cannot be inquired_token, the other similar stage 1.If S meets access knot Structure, then (S, kw₀) and ((S, kw₁) cannot inquire

Conjecture: A exports a conjecture μ '.If μ=μ ', challenger's outputOtherwise, it exports

So far the simulation of game is completed.Now game probability is won to challenger under conditions of working properly to analyze. If outputSo cph^*Actually kw_μAn effective ciphertext, so A output μ=μ ' probability be 1/2+ ε.If Z is from G₃In it is randomly selected, then A output μ=μ ' probability be 1/2.Therefore, challenger correctly guessesProbability be 1/2 ε/2 (1/2+ ε)+1/21/2=1/2+.

That is, it is (1/e+1/q that challenger, which has the advantage for solving the problems, such as 4-MDDH,_T)ε/2。

5 functional analyses

In this section, the present invention is proposed a plan and is compared with the method for document [1], document [2] from aspect of performance, is seen Table 1.The scheme support of document [1] can search for encrypting but not support re-encryption, and disadvantageous inhabitant shares data retrieval permissions, searches The flexibility of rope reduces；And tree-like access structure efficiency is lower, this is not accounted in the data forwarding of cloud computing and search mechanisms Advantage.Document [16] uses the encryption attribute side based on key strategy though keyword search and proxy re-encryption may be implemented Case pole is unfavorable for control of the data owner for access authority.And the present invention program is due to using the higher LSSS knot of access efficiency Structure, can be realized simultaneously the function of keyword search and proxy re-encryption, therefore be more suitable for cloud computing and practical application.

[1]Zheng Q,Xu S,Ateniese G.VABKS:Verifiable attribute-based keyword search over outsourced encrypted data[C]//Proc of IEEE INFOCOM.2014:522-530.

[2]Liang K,Susilo W.Searchable Attribute-based mechanism with efficient data sharing for secure cloud storage[J].IEEE Trans on Information Forensics&Security,2015,10(9):1981-1992.

1 scheme performance of table compares

6 efficiency analysis

This section will compare in terms of efficiency with document [1], document [2], and comparison result is shown in Table 2.Wherein s indicates attribute Attribute number is concentrated, l indicates the number of attribute in access structure, and E is used to indicate that an index operation exponent arithmetic on G, P It is to indicate that Bilinear map matches operation.Since hash algorithm, the non-index operation calculation amount generated on first group element are smaller, therefore neglect Slightly disregard the calculation amount of two kinds of algorithms.

2 computing cost of table compares

The solution of the present invention is generated in key as can be seen from Table 2 and ciphertext generation phase is substantially better than document [1].Surely belong to Property concentrate attribute number it is close with access structure number when, the present invention program will be much higher than document in the efficiency of key generation phase [2], in threshold generation and search phase, simultaneously above both schemes.Added this is because the present invention is used based on Ciphertext policy Close mode and document [2] calculate access structure key strategy using key generation phase, therefore efficiency reduces.Even if raw in ciphertext After the computations of access control are added at the stage, the efficiency of the present invention program is still higher than document [2].Comprehensive analysis can obtain, This programme has more practicability compared to the search plan based on attribute in same stage.

7 effects

For searching ciphertext existing under cloud environment, retrieval permissions are shared and access control problem, the present invention use crucial The mode of word and ciphertext segmentation operation, in conjunction with the property broker re-encryption scheme based on key strategy, proposing a kind of cloud can Control the cipher text searching scheme based on attribute of search permission.Scheme under the conditions of ciphertext, can carry out the data of condition setting beyond the clouds Retrieval and search permission it is shared.Meanwhile in conjunction with cloud computing ability, saves and be locally stored and the cost of management service, mention High retrieval rate, so that user still is able to shared search permission in the case where online.Although scheme realizes access control It makes, improve retrieval rate, but functionally, can only realize the search of single keyword, still can not achieve multiple key or key The functions such as fuzzy query, sequence, the relational calculus of word, therefore how to solve the above problems, and following research direction.

Under cloud storage environment, the searching ciphertext scheme of keyword search is supported to cannot achieve fine-granularity access control, it cannot Search permission is shared.For this purpose, the present invention mutually ties the encipherment scheme that can search for based on attribute with proxy re-encryption technology Close the cipher text searching scheme based on attribute for proposing a kind of controllable search permission in cloud.In the present solution, using keyword and ciphertext Divide the mode of operation, the access structure and keyword of multiple attribute compositions realize search access control；Pass through proxy re-encryption In the case that technology can realize that user is not online, search permission is shared with to the other users for meeting access conditions.Safety analysis Show that this programme can be with the safety of valid certificates this programme under polyteny Decisional Diffie-Hellman assumption.

The preferable specific embodiment of the above, only the invention, but the protection scope of the invention is not It is confined to this, anyone skilled in the art is in the technical scope that the invention discloses, according to the present invention The technical solution of creation and its inventive concept are subject to equivalent substitution or change, should all cover the invention protection scope it It is interior.

Claims (9)

1. a kind of cipher text searching method based on attribute of controllable search permission, which comprises the steps of:

S1. system is established, and obtains common parameter and main private key；

S2. key generates: inputting the attribute set and main private key of user, obtains the private key for user of corresponding attribute set；

S3. ciphertext generates: input access structure, common parameter, main private key and keyword, data owner execute algorithm and generate original Ciphertext；

S4. threshold generation: input common parameter, private key and keyword to be checked, data owner generate the token of keyword；

S5. re-encrypted private key generates: input common parameter, private key, access structure obtain re-encrypted private key；

S6. re-encryption ciphertext generates: input common parameter, initial ciphertext and re-encrypted private key, it is close that Cloud Server exports re-encryption Text；

S7. cipher text searching: former ciphertext and data owner's token are inputted, cipher text searching algorithm is executed；

S8. re-encryption cipher text searching: input re-encryption ciphertext and data consumer's token execute cipher text searching algorithm.

2. the cipher text searching method based on attribute of controllable search permission as described in claim 1, which is characterized in that

The step of system is established, and common parameter and main private key are obtained is as follows:

System is established setup (N, n): the maximum number of column n of the attribute total number N and access control matrix M of input system, generates one A 4- multilinear pairing: { e_i:G₀×G_i→G_i+1| i=0,1,2 }, wherein (G₀,...,G₃) it is the plain rank cyclic group that rank is p, it enables g₀∈G₀, g₀It is G₀Generation member, and for i=0,1,2, g_i+1=e_i(g₀,g₁) it is G_i+1Generation member, take h_1,1,h_1,2,..., h_n,N∈G₀, define hash function H:{ 0,1 }^*→G₀, randomly select Expression integer set 0,1 ..., p- 1 }, then common parameter is and main private key are as follows:

Msk=(a, b) (2).

3. the cipher text searching method based on attribute of controllable search permission as claimed in claim 2, which is characterized in that

The step of key generates is as follows:

Key generates keyGen (msk, S): inputting the attribute set S and main private key msk of user, randomly selects index t₁, ...t_n←Z_P, Z_PIndicate the set of integer { 0,1 ..., p-1 }, ifX ∈ S is taken,The raw private key of the user of corresponding attribute set S are as follows:

Sk=(D, { L_j}j∈[1,n],{D_x}x∈S) (3)。

4. the cipher text searching method based on attribute of controllable search permission as claimed in claim 3, which is characterized in that ciphertext is raw At the step of it is as follows:

Ciphertext generates Enc (kw, pp, msk, (M, ρ)): input access structure (M, ρ), common parameter pp, main private key msk and key Word kw ∈ { 0,1 }^*, data owner executes the algorithm and generates former ciphertext, the line number and columns of matrix M are respectively indicated with l and n, The every a line of access structure is associated with attribute, defining the mapping function is ρ, and calculating randomly selects n-1 random element and selection s ←Z_PVector is formed as shared secretFor i ∈ { 1,2 ..., l }, takeWith j ∈ { 1 ..., n } is calculated

And obtain ciphertext:

Cph=((M, ρ), A_i,j,B,C_i,C₁,C₂)_{i∈[1,l],j∈[1,n]} (4)。

5. the cipher text searching method based on attribute of controllable search permission as claimed in claim 4, which is characterized in that thresholding is raw At the step of it is as follows:

TokenGen (pp, sk, kw): input common parameter pp, private key sk and keyword kw to be checked, for i ∈ 1,2 ..., L } calculate separately T₁=e₀(H (kw), D), T_j=e₀(H(kw),L_j), T_x=e₀(H(kw),D_x) x ∈ S, then data owner generates The token of keyword kw are as follows:

Token=(S, T₁,{T_j}_j∈[1,n],{T_x}_∈S) (5)。

6. the cipher text searching method based on attribute of controllable search permission as claimed in claim 5, which is characterized in that re-encryption The step of key generates is as follows:

Re-encrypted private key generate ReKeyGen (pp, sk, (M ', ρ ')): input common parameter pp, private key sk, access structure (M ', ρ '), the line number and columns of matrix M ' are respectively indicated with l and n, and the every a line of access structure is associated with attribute, defines the mapping letter Number is ρ ', randomly selects n-1 element and composition vectors immediatelyFor i ' ∈ { 1,2 ..., l }, It takesWith j ' ∈ { 1 ..., n }, calculate

Export re-encrypted private key are as follows:

rk_(M′,ρ′)=(B ', { A '_i,j}_{i∈[1,l],j∈[1,n]}) (6)。

7. the cipher text searching method based on attribute of controllable search permission as claimed in claim 6, which is characterized in that re-encryption The step of ciphertext generates is as follows:

Re-encryption ciphertext generates ReEnc (cph, pp, rk_(M′,ρ′)): input common parameter pp, initial ciphertext cph=(C₁,C₂) and Re-encrypted private key rk_(M′,ρ′), calculateCloud Server exports re-encryption ciphertext are as follows:

cph^R=((M ', ρ '), C '₁,C′₂,B′,{A_i,j}_{i∈[1,l],j∈[1,n]}) (7)。

8. the cipher text searching method based on attribute of controllable search permission as claimed in claim 7, which is characterized in that ciphertext is searched The step of rope, is as follows:

Cipher text searching Search (token, cph): input original ciphertext cph and data owner token token executes cipher text searching Algorithm, whether verifying user property collection S meets access structure P=(M, ρ), if it is satisfied, then centainly can be in polynomial time Inside obtain set c_i, which meets ∑_ρ(i)∈Sc_i·λ_i=(1,0 ..., 0), then it calculates

IfIt then proves to search for successfully, otherwise search failure.

9. the cipher text searching method based on attribute of controllable search permission as claimed in claim 8, which is characterized in that re-encryption The step of cipher text searching, is as follows:

Re-encryption cipher text searching Search^R(token^R,cph^R): input re-encryption ciphertext cph^RAnd data consumer's token Token executes cipher text searching algorithm, and whether verifying user property collection S meets access structure P=(M ', ρ '), if it is satisfied, then Set c ' can be centainly obtained in polynomial time_i, which meets ∑_ρ′(i)∈Sc′_i·λ′_i=(1,0 ..., 0), then It calculates

If e₂(K′,C′₁)=C '₂, then prove to search for successfully, otherwise search failure.