CN104038349A - Effective and verifiable public key searching encryption method based on KP-ABE - Google Patents

Abstract

The invention discloses an effective and verifiable public key searchable encryption method based on KP-ABE. The method includes a trusted authority center, a data owner, a cloud server, and a data user; the trusted authority center generates certificates for all cloud users ; The data owner outsources data files and keywords to the cloud server; the cloud server provides storage services and executes the search operation after receiving the search request sent by the user; the data user generates a search password and sends it to the cloud server to find the target file. The present invention firstly generates a public-private key pair for the data owner and the cloud server, and when sending the cipher text keywords and search passwords, first uses the public key of the cloud server to re-encrypt them, thus effectively preventing offline guessing by external attackers The attack behavior improves the security of information and data, and the complexity is reduced, which greatly reduces the user's calculation load and greatly improves the efficiency.

Description

An Effectively Verifiable Public Key Searchable Encryption Method Based on KP-ABE

technical field

The invention belongs to the field of data encryption, in particular to an effective and verifiable public key searchable encryption method based on KP-ABE.

Background technique

Public-key searchable encryption is a very attractive cryptographic primitive, which implements information retrieval based on ciphertext, and is especially suitable for cloud computing environments. Public Key Searchable Encryption Scheme (PEKS) enables users to search encrypted data by keywords without revealing any information. The concept of PEKS was proposed by Boneh et al. Baek et al. proposed a PEKS that removes the security channel, making the solution more practical. Following this, Hu et al. and Zhao et al. proposed new schemes that are resistant to offline keyword guessing by external attackers. In short, the concept of PEKS is to provide a mechanism for users to search encrypted data by keywords without disclosing any information to other parties including the server. With the rapid development of cloud computing, users can use the massive storage and computing capabilities of cloud servers at low prices. This has made PEKS even more popular. Although the existing PEKS can safely and effectively complete the search operation, most of the solutions do not verify the search results returned by the server, and do not restrict the search users. Under a model of semi-honest but trusted servers, the server may only perform part of the search operation or return only part of the search results. In response to this problem, Zheng et al. proposed a new cryptographic primitive for this problem for the first time—a verifiable keyword search scheme based on attribute encryption. This scheme allows data owners to control search operations. Legitimate users of access control policies can outsource time-consuming search operations to cloud servers and can effectively verify that the server actually performed the search operation. This means that users who meet the conditions of the data owner's access policy can search the encrypted data on the cloud server. In addition, users can also verify the correctness and completeness of the search results returned by the server. The scheme is constructed by using modular exponent, attribute encryption, Bloom filter, digital signature and keyword search based on attribute encryption. However, this solution performs the same operation as the cloud server when verifying the correctness, but for the user itself, this requires a large amount of calculation. In addition, the scheme ignores the offline guessing attack. Because the keyword ciphertext, search password and algorithm are easily obtained by the adversary, the adversary can perform the search operation, thus breaking the indistinguishability of the keyword ciphertext.

Contents of the invention

The purpose of the present invention is to provide an effective and verifiable public key searchable encryption method based on KP-ABE, which aims to greatly reduce the user's calculation load in terms of correctness verification, and use the server's public key to re-encrypt the keyword ciphertext. Encryption prevents offline guessing attacks by external attackers and improves the security of the solution.

Symbol Description:

F＝{F ₁ }||{F ₂ }||...||{F _n }: collection of encrypted files;

ID{F _i }: address of file {F _i };

ID _w : the address of the file containing the keyword w;

W _E : W's ciphertext;

BF: Bloom filter containing all keywords;

SYM _Enc (): Symmetric encryption algorithm;

ABE(): Key policy-based attribute encryption algorithm.

The present invention is achieved in this way, an effective and verifiable public key searchable encryption method based on KP-ABE, and the effective and verifiable public key searchable encryption method based on KP-ABE includes a trusted authority center, data Owner, cloud server, data user; the trusted authority center selects bilinear pairing and hash function to generate public parameter pm and master key mk for the system; generates public and private keys for data owner and cloud server by running RSA algorithm Yes; through the Share(T,ac) algorithm in the access structure, generate a private key sk for the user; the data owner extracts the keyword w from the outsourced data file F; outsource F, and generate the keyword w ciphertext cph and send it To the cloud server; the cloud server provides storage services for the data sent by the data owner and executes the search after receiving the search password tk sent by the user, and returns the search results and search evidence to the user; the data user uses the private key sk to generate a search The password tk is sent to the cloud server; after receiving the search result returned by the cloud server, the correctness and completeness of the result are verified;

The described effective and verifiable public key searchable encryption method based on KP-ABE comprises six algorithms, l is a security parameter, and the credible authority center runs the RSA algorithm to generate a public-private key pair for the cloud server and the data owner: {(n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ }; the data owner guarantees the integrity of the data file through digital signature, and uses the public key of the cloud server to reconstruct the ciphertext keywords. Encryption to prevent offline guessing attacks by external attackers. When the data owner encrypts the data file with the SYM _Enc () encryption algorithm and outsources it to the cloud server, the server returns the address of the encrypted file, which is recorded as ID{F _i }, which contains the key The data file of word w can be expressed as ID _w =ID{F ₁ }||ID{F ₂ }...||ID{F _i }.

Further, the public key searchable encryption method specifically includes:

The trusted authority center selects bilinear pairing and hash function as a searchable encryption system: the trusted authority center manages data owners, users and cloud servers;

The data owner sends the data file to the cloud server;

Cloud servers provide storage and retrieval services;

The user searches the data files stored on the cloud server through the cloud server;

The trusted authority center generates the public parameter pm and the master key mk; by running the following RSA algorithm:

Follow these 3 steps:

i) select different large prime numbers p and q, and calculate n=p*q;

ii) Choose e with Mutually prime, (n, e) as the public key;

iii) pass Calculate d, (n,d) as the private key;

here The numbers n, e, and d are modulus, encryption index and decryption index respectively;

According to this algorithm, select different large prime numbers p ₁ and q ₁ , p ₂ and q ₂ to generate public-private key pairs {(n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ };

By accessing the Share(T,ac) algorithm in the structure, follow the steps below:

Each leaf node of the access tree T is associated with the partial share q _v (0) of the secret ac. For each leaf node v∈lvs(T), select t←Z _p and calculate and B _v =g ^t , record sk=(T,A _v ,B _v )|v∈lvs(T)) as the user's private key.

Further, the effective and verifiable public key searchable encryption method based on KP-ABE includes six algorithms, l is a security parameter, and the trusted authority center runs the RSA algorithm to generate a public-private key pair for the cloud server and the data owner:{ (n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ }. The data owner guarantees the integrity of the data file through a digital signature, and re-encrypts the ciphertext keywords with the public key of the cloud server to prevent offline guessing attacks by external attackers. When the data owner uses the SYM _Enc () encryption algorithm to encrypt After the data file is encrypted, it is outsourced to the cloud server, and the server returns the address of the encrypted file, which is recorded as ID{F _i }, so that the data file containing the keyword w can be expressed as ID _w = ID{F ₁ }||ID{F ₂ }...||ID{F _i }.

Further, the specific scheme of the effective and verifiable public key searchable encryption method based on KP-ABE is:

Step 1. Initialization (1 ^l ): The trusted authority center selects a bilinear pairing: e:G×G→G _T , where G and G _T are cyclic groups of order p, and p is a prime element with a length of l bits. Select The hash function H ₁ :{0,1} ^* →G under the random oracle model; H ₂ :{0,1} ^* →Z _p is a one-way hash function, choose a,b,c←Z _p , g←G, pm=(H ₁ ,H ₂ ,e,g,p,g ^a ,g ^b ,g ^c ,G,G _T ),mk=(a,b,c)

Then select k independent hash functions H ₁ ',...,H' _k , use m bits to construct m bits Bloom filter BF and send it to the data owner to generate a public-private key pair for the data owner and the cloud server {(n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ };

Step 2, key generation (mk, T): the trusted authority center executes the Share(T, ac) algorithm, and each leaf node of the access tree T will get the partial share q _v (0) of the secret ac, for each For leaf node v∈lvs(T), select t←Z _p and calculate Sum B _v ＝g ^t , remember the private key sk＝(T,A _v ,B _v )|v∈lvs(T));

Step 3. Encryption of keywords and file addresses: (w,atts,ID(w)) The data owner generates a Bloom filter through the hash function sent by the trusted authority center, BF←BFGen({H ₁ ', …,H' _k },{w ₁ ,…,w _l }), for data file address ID w containing keyword _w and Bloom filter, SYM _Enc () encryption algorithm encryption, symmetric key is sk ₁ :

BF _Enc =SYM(BF),(ID _w ) _Enc =SYM(ID _w );

User data owner signs ABF _Enc and (ID _w ) _Enc : $A={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|\mathrm{sig}\left({\mathrm{BF}}_{\mathrm{Enc}}\right)={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|{\left({\mathrm{BF}}_{\mathrm{Enc}}\right)}^{d_1},B={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|\mathrm{sig}{\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|{\left({\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\right)}^{d_1}$ Encrypt sk ₁ with the ABE () encryption algorithm: C=ABE(sk ₁ );

After the search is over, legitimate users whose attributes meet the access policy can decrypt C to obtain sk ₁ , and then decrypt to obtain the target file;

Choose r ₁ ,r ₂ ←Z _p , calculate $W^{\′}=g^{{\mathrm{cr}}_1},W=g^{a(r_1+r_2)}{g}^{b{h}_2\left(w\right)r_1};$ F=(f ₁ ,f ₂ ) where $f_1=g^{a(r_1+r_2)},f_2=g^{{\mathrm{br}}_1},W_0=g^{r_2},$ For each at _j ∈ Atts, compute $W_j=h_1{\left({\mathrm{at}}_j\right)}^{r_2},$ Encrypt W with the server's public key to get $W_{\mathrm{E.}}=W^{e_2}={\left(g^{a(r_1+r_2)}{g}^{{\mathrm{bH}}_2\left(w\right)r_1}\right)}^{e_2},$ In this way, the ciphertext keywords can be recorded as: cph=(Atts, W', W _E , W ₀ , W _j , F, A, B, C);

Step 4. Generate search password (sk,w): select s←Z _p , calculate for each leaf node v∈lvs(T) $A_v^{\′}=A_v^{\mathrm{the\; s}},B_v^{\′}=B_v^{\mathrm{the\; s}},$ The search password is ${\mathrm{tok}}_1={\left(g^a{g}^{{\mathrm{bH}}_2\left(w\right)}\right)}^{\mathrm{the\; s}},$ tok ₂ = g ^cs , encrypt tok ₂ with the server's public key: Remember tk＝(tok ₁ ,(tok ₂ ) _Enc ,T,(A' _v ,B' _v )|v∈lvs(T));

Step 5. Search (tk,cph): The server selects the attribute set S from cph to satisfy the access tree specified in the search password. If such a set S does not exist, return 0; otherwise, for each at _j ∈ S, calculate ${\mathrm{E.}}_v=e(A_v^{\′},W_0)/e(B_v^{\′},W_j)=e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}\mathrm{att}\left(v\right)={\mathrm{at}}_j,v\∈\mathrm{lvs}\left(T\right),$ Combining (T,E _v |att(v)∈S), calculate $e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}=e{(g,g)}^{{\mathrm{sr}}_2{q}_{\mathrm{root}}\left(0\right)},$ and then ${\mathrm{E.}}_{\mathrm{root}}=e{(g,g)}^{{\mathrm{acsr}}_2}$ The server decrypts W _E with its own private key, (tok ₂ ) _Enc to get W and tok ₂ , if e(W',tok ₁ )E _root ＝e(W,tok ₂ ), return {W,F,A,B ,C} to the user; otherwise, just return A;

Step 6. Verification {W, F, A, B, C} data The user performs verification operation after receiving the search result returned by the cloud server.

Further, the specific method of the verification operation is:

Step 1. Search for the existence of keywords: When the data user only receives A returned by the cloud server, first use the public key A of the data owner to verify if Then the verification is passed; decrypt C to obtain the symmetric key sk ₁ , decrypt A to obtain the Bloom filter BF, if BF(w)=0, it means that the keyword searched by the user does not exist on the cloud server, otherwise, reject Return the result;

Step 2. The correctness of the search keywords: when the data user receives {W, F, A, B, C}, calculate W/f ₁ and if The explanation is correct, otherwise, the explanation is a wrong result;

Step 3. Integrity of the address of the data file containing the keyword w: After the data user verifies the correctness of the keyword, then verify B, if Then obtain sk ₁ by decrypting C, and then obtain the target data file.

Further, the analysis of the correctness of the effective and verifiable public key searchable encryption method based on KP-ABE is as follows:

Step 1. Search for matching correctness:

After the cloud server receives the search request from the data user, it executes the search operation. First, it uses its own private key to decrypt the ciphertext keyword and the search password, uses the RSA algorithm, and then performs the following matching operations:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; W</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; tok</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; root</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; cr</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\\ \mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; acs</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>\end{array}$

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; tok</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; cs</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\\ \mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; acs</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; .</span>\end{array}$

If w and w ₁ are the same keyword, then e(W',tok ₁ )E _root and e(W,tok ₂ ) are equal, indicating that the search is successful;

Step 2. Verify correctness:

When the data user receives the search result {W,F,A,B,C} returned by the cloud server, he must first verify the correctness of the keywords, find f ₁ and f ₂ from F, and perform the following calculation:

$\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; b</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

The hash value H ₂ (w ₁ ) of the keyword that the user searches for is calculated as follows:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

If w and w ₁ are the same keyword, Equal, it means that the search result is correct. After that, verify the correctness and integrity of the address of the data file through the signature.

Effect summary

The effective and verifiable public-key searchable encryption method based on KP-ABE of the present invention first generates a public-private key pair for the data owner and the cloud server, and first uses the public-private key pair of the cloud server when sending ciphertext keywords and search passwords. It is re-encrypted with the key, which effectively prevents offline guessing attacks by external attackers, improves the security of the scheme, and reduces the complexity, greatly reduces the amount of calculation for users, and greatly improves the efficiency.

Description of drawings

Fig. 1 is a model schematic diagram of an effective and verifiable public key searchable encryption method based on KP-ABE provided by an embodiment of the present invention;

Fig. 2 is a comparison chart of the execution time of the correctness verification of the present invention and the comparison scheme provided by the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The present invention is realized in this way, as shown in Figure 1, a kind of effective and verifiable public key searchable encryption method based on KP-ABE comprises trusted authority center, data owner, cloud server, data user; Trusted authority center Generate certificates for all cloud users; data owners outsource data files and keywords to cloud servers; cloud servers provide storage services and perform search operations after receiving search requests from users; data users generate search passwords and send them to cloud servers to find Target file.

Further, the public key searchable encryption method specifically includes:

The trusted authority center selects bilinear pairing and hash function as a searchable encryption system: the trusted authority center manages data owners, users and cloud servers;

The data owner sends the data file to the cloud server;

Cloud servers provide storage and retrieval services;

The user searches the data files stored on the cloud server through the cloud server;

The trusted authority center generates the public parameter pm and the master key mk; by running the following RSA algorithm:

Follow these 3 steps:

i) select different large prime numbers p and q, and calculate n=p*q;

ii) Choose e with Mutually prime, (n, e) as the public key;

iii) pass Calculate d, (n,d) as the private key;

here The numbers n, e, and d are modulus, encryption index and decryption index respectively;

According to this algorithm, select different large prime numbers p ₁ and q ₁ , p ₂ and q ₂ to generate public-private key pairs {(n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ };

By accessing the Share(T,ac) algorithm in the structure, follow the steps below:

Each leaf node of the access tree T is associated with the partial share q _v (0) of the secret ac. For each leaf node v∈lvs(T), select t←Z _p and calculate and B _v =g ^t , record sk=(T,A _v ,B _v )|v∈lvs(T)) as the user's private key.

Further, the effective and verifiable public key searchable encryption method based on KP-ABE includes six algorithms, l is a security parameter, and the trusted authority center runs the RSA algorithm to generate a public-private key pair for the cloud server and the data owner:{ (n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ }, the data owner guarantees the integrity of the data file through digital signature, and uses the public key of the cloud server to pair the ciphertext keywords Perform re-encryption to prevent offline guessing attacks by external attackers. When the data owner encrypts the data file with the SYM _Enc () encryption algorithm and outsources it to the cloud server, the server returns the address of the encrypted file, which is recorded as ID{F _i }, so A data file containing the keyword w can be expressed as ID _w =ID{F ₁ }||ID{F ₂ }...||ID{F _i }.

Further, the specific scheme of the effective and verifiable public key searchable encryption method based on KP-ABE is:

Step 1. Initialization (1 ^l ): The trusted authority center selects a bilinear pairing: e:G×G→G _T , where G and G _T are cyclic groups of order p, and p is a prime element with a length of l bits. Select The hash function H ₁ :{0,1} ^* →G under the random oracle model; H ₂ :{0,1} ^* →Z _p is a one-way hash function, choose a,b,c←Z _p , g←G, pm=(H ₁ ,H ₂ ,e,g,p,g ^a ,g ^b ,g ^c ,G,G _T ),mk=(a,b,c)

Then select k independent hash functions H ₁ ',...,H' _k , use m bits to construct m bits Bloom filter BF and send it to the data owner to generate a public-private key pair for the data owner and the cloud server {(n ₁ ,e ₁ ),d ₁ } and {(n ₂ ,e ₂ ),d ₂ };

Step 2, key generation (mk, T): the trusted authority center executes the Share(T, ac) algorithm, and each leaf node of the access tree T will get the partial share q _v (0) of the secret ac, for each For leaf node v∈lvs(T), select t←Z _p and calculate Sum B _v ＝g ^t , remember the private key sk＝(T,A _v ,B _v )|v∈lvs(T));

Step 3. Encryption of keywords and file addresses: (w,atts,ID(w)) The data owner generates a Bloom filter through the hash function sent by the trusted authority center, BF←BFGen({H ₁ ', …,H' _k },{w ₁ ,…,w _l }), for data file address ID w containing keyword _w and Bloom filter, SYM _Enc () encryption algorithm encryption, symmetric key is sk ₁ :

BF _Enc =SYM(BF),(ID _w ) _Enc =SYM(ID _w );

User data owner signs ABF _Enc and (ID _w ) _Enc : $A={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|\mathrm{sig}\left({\mathrm{BF}}_{\mathrm{Enc}}\right)={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|{\left({\mathrm{BF}}_{\mathrm{Enc}}\right)}^{d_1},B={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|\mathrm{sig}{\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|{\left({\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\right)}^{d_1}$ Encrypt sk ₁ with the ABE () encryption algorithm: C=ABE(sk ₁ );

After the search is over, legitimate users whose attributes meet the access policy can decrypt C to obtain sk ₁ , and then decrypt to obtain the target file;

Choose r ₁ ,r ₂ ←Z _p , calculate $W^{\&prime;}=g^{{\mathrm{cr}}_1},W=g^{a(r_1+r_2)}{g}^{b{h}_2\left(w\right)r_1};$ F=(f ₁ ,f ₂ ) where $f_1=g^{a(r_1+r_2)},f_2=g^{{\mathrm{br}}_1},W_0=g^{r_2},$ For each at _j ∈ Atts, compute $W_j=h_1{\left({\mathrm{at}}_j\right)}^{r_2},$ Encrypt W with the server's public key to get $W_{\mathrm{E.}}=W^{e_2}={\left(g^{a(r_1+r_2)}{g}^{{\mathrm{bH}}_2\left(w\right)r_1}\right)}^{e_2},$ In this way, the ciphertext keyword can be remembered as: cph=(Atts, W', W _E , W ₀ , W _j , F, A, B, C);

Step 4. Generate search password (sk,w): select s←Z _p , calculate for each leaf node v∈lvs(T) $A_v^{\&prime;}=A_v^{\mathrm{the\; s}},B_v^{\&prime;}=B_v^{\mathrm{the\; s}},$ The search password is ${\mathrm{tok}}_1={\left(g^a{g}^{{\mathrm{bH}}_2\left(w\right)}\right)}^{\mathrm{the\; s}},$ tok ₂ = g ^cs , encrypt tok ₂ with the server's public key: Remember tk＝(tok ₁ ,(tok ₂ ) _Enc ,T,(A' _v ,B' _v )|v∈lvs(T));

Step 5. Search (tk,cph): The server selects the attribute set S from cph to satisfy the access tree specified in the search password. If such a set S does not exist, return 0; otherwise, for each at _j ∈ S, calculate ${\mathrm{E.}}_v=e(A_v^{\&prime;},W_0)/e(B_v^{\&prime;},W_j)=e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}\mathrm{att}\left(v\right)={\mathrm{at}}_j,v\&Element;\mathrm{lvs}\left(T\right),$ Combining (T,E _v |att(v)∈S), calculate $e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}=e{(g,g)}^{{\mathrm{sr}}_2{q}_{\mathrm{root}}\left(0\right)},$ and then ${\mathrm{E.}}_{\mathrm{root}}=e{(g,g)}^{{\mathrm{acsr}}_2}$ The server decrypts W _E with its own private key, (tok ₂ ) _Enc to get W and tok ₂ , if e(W',tok ₁ )E _root ＝e(W,tok ₂ ), return {W,F,A,B ,C} to the user; otherwise, just return A;

Step 6. Verification {W, F, A, B, C} data The user performs verification operation after receiving the search result returned by the cloud server.

Further, the specific method of the verification operation is:

Step 1. Search for the existence of keywords: When the data user only receives A returned by the cloud server, first use the public key A of the data owner to verify if Then the verification is passed; decrypt C to obtain the symmetric key sk ₁ , decrypt A to obtain the Bloom filter BF, if BF(w)=0, it means that the keyword searched by the user does not exist on the cloud server, otherwise, reject Return the result;

Step 2. The correctness of the search keywords: when the data user receives {W, F, A, B, C}, calculate W/f ₁ and if The explanation is correct, otherwise, the explanation is a wrong result;

Step 3. Integrity of the address of the data file containing the keyword w: After the data user verifies the correctness of the keyword, then verify B, if Then obtain sk ₁ by decrypting C, and then obtain the target data file.

Further, the analysis of the correctness of the effective and verifiable public key searchable encryption method based on KP-ABE is as follows:

Step 1. Search for matching correctness:

After the cloud server receives the search request from the data user, it executes the search operation. First, it uses its own private key to decrypt the ciphertext keyword and the search password, uses the RSA algorithm, and then performs the following matching operations:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; W</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; tok</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; root</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; cr</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\\ \mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; acs</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>\end{array}$

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; tok</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; cs</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\\ \mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; acs</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; e</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; .</span>\end{array}$

If w and w ₁ are the same keyword, then e(W',tok ₁ )E _root and e(W,tok ₂ ) are equal, indicating that the search is successful;

Step 2. Verify correctness:

When the data user receives the search result {W,F,A,B,C} returned by the cloud server, he must first verify the correctness of the keywords, find f ₁ and f ₂ from F, and perform the following calculation:

$\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; b</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

The hash value H ₂ (w ₁ ) of the keyword that the user searches for is calculated as follows:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; g</span>}}^{{\mathrm{<span\; class="notranslate">\; bH</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

If w and w ₁ are the same keyword, W/f ₁ and Equal, it means that the search result is correct. After that, verify the correctness and integrity of the address of the data file through the signature.

The present invention is compared with the scheme in the document "Verifiable attribute-based keyword search overoutsourced encrypted data" (Q. Zheng, Xu, S. Ateniese, G.: Vabks, IACR Cryptology ePrint Archive2013 (2013)), in the present invention In the scheme, firstly, a public-private key pair is generated for the data owner and the cloud server. When sending the ciphertext keywords and search passwords, firstly use the public key of the cloud server to re-encrypt them, which effectively prevents offline attacks by external attackers. Guess the attack. This is not covered in the comparison. In addition, compared with the comparison scheme, the operation performed by the comparison scheme when verifying correctness is the same as that of the cloud server, while the method used in the present invention has obvious advantages, as shown in Table 1:

Table 1

BF stands for Bloom filter; here the complexity considers the asymptotic complexity, mainly Pair and E _T . Pair represents bilinear pairing operation; E _T represents the exponential operation in group G _T ; S represents the number of attributes of the user. As in the comparison scheme, because the multiplication and hashing operations are less complex than the pairing and exponentiation operations. So when discussing complexity, multiplication and hash operations are ignored.

The user verifies the correctness of the search results returned by the server:

C language programming, using Ubuntu Linux12.04 system. Computer configuration: Intel(R) Core(TM) i3-3240Cpu, 2GB RAM. Pairwise-Based Cryptography (PBC) Lab Version 0.514. All experimental results are the average value of 50 experiments. The modulus lengths of 512 bits and 1024 bits are respectively selected, and the number of attributes ranges from 10 to 50. Finally, as shown in Figure 2, the experimental results show that the verification method of the present invention has high efficiency and stronger practicability.

Fig. 2 shows the execution time of correctness verification for the scheme of the present invention and the comparison scheme. Compared with the comparison scheme, the running time of the scheme of the present invention does not change with the increase of the number of attributes, which further illustrates the practicability of the present invention. The double slashes in the figure represent interruptions in the vertical direction, and ORIGIN8.0 software was used here for data analysis and graphing.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay any creative effort. Various modifications or deformations that can be made by labor are still within the protection scope of the present invention.

Claims (6)

1. the PKI that effectively can verify based on KP-ABE can be searched for an encryption method, it is characterized in that, the described PKI that effectively can verify based on KP-ABE can be searched for encryption method and comprise the following steps:

Data owner extracts keyword w from the data file F of outsourcing; Outsourcing F, and generate keyword w ciphertext cph and send to Cloud Server;

The data that Cloud Server sends data owner provide stores service and after receiving the search password tk that user sends, carry out search, and Search Results and search evidence are returned to user;

Data user generates search password tk and sends to Cloud Server with private key sk; After receiving the Search Results that Cloud Server returns, the correctness of result and integrality are verified.

2. the PKI that effectively can verify based on KP-ABE as claimed in claim 1 can be searched for encryption method, it is characterized in that, described PKI can be searched for encryption method and specifically comprise:

Can search for encryption system: trusted authorization centre management data owner, user and Cloud Server;

Data owner is sent to Cloud Server by data file;

Cloud Server provides storage and retrieval service;

User searches for data file stored thereon by Cloud Server;

Trusted authority center choose bilinearity to and hash function, and generate public ginseng pm and master key mk; By moving following RSA Algorithm:

Press following 3 steps:

I) select different large prime number p and q, calculate n=p*q;

Ii) select e with coprime, (n, e) is as PKI;

Iii) pass through calculate d, (n, d) is as private key;

Here number n, e, d is respectively modulus, encryption exponent and decryption exponent;

According to this algorithm, choose different large prime number p ₁and q ₁, p ₂and q ₂, be data owner and server generation public private key pair { (n ₁, e ₁), d ₁and { (n ₂, e ₂), d ₂;

By Share (T, the ac) algorithm in access structure, as follows:

Each leaf node of access tree T associated the part of secret ac share q _v(0),, to each leaf node v ∈ lvs (T), choose t ← Z _p, calculate and B _v=g ^t, note sk=(T, A _v, B _v) | v ∈ lvs (T)) be user's private key.

3. the PKI that effectively can verify based on KP-ABE as claimed in claim 1 can be searched for encryption method, it is characterized in that, the described PKI that effectively can verify based on KP-ABE can be searched for encryption method and comprise: initialization, key generate, the encryption of keyword and file address, generation are searched for to password, search, checking; The method is mainly used in the search to a large amount of enciphered datas in cloud computing.

4. the PKI that effectively can verify based on KP-ABE as claimed in claim 1 can be searched for encryption method, it is characterized in that, the concrete scheme that the described PKI that effectively can verify based on KP-ABE can be searched for encryption method is:

Trusted authority center operation RSA Algorithm is that Cloud Server and data owner generate public private key pair: { (n ₁, e ₁), d ₁and { (n ₂, e ₂), d ₂; Data owner guarantees the integrality of data file by digital signature; With the PKI of Cloud Server, ciphertext keyword is encrypted to prevent again the off-line guessing attack of external attacker, as data owner SYM _enc() cryptographic algorithm is contracted out to Cloud Server after to data file encryption, and server returns to the address of encrypt file, is designated as ID{F _i, the data file that comprises like this keyword w can be expressed as ID _w=ID{F ₁|| ID{F ₂... || ID{F _i; Specifically comprise:

Step 1, initialization (1 ^l): bilinearity pair: e:G * G → G is selected at trusted authority center _t, G and G _tbe that rank are the cyclic group of p, p is the primitive element of l bit long, selects the hash function H under random oracle ₁: { 0,1} ^*→ G; H ₂: { 0,1} ^*→ Z _pbe one-way Hash function, select a, b, c ← Z _p, g ← G,

pm＝(H ₁,H ₂,e,g,p,g ^a,g ^b,g ^c,G,G _T),

mk＝(a,b,c)

Then choose k independently hash function H ₁' ..., H' _k, be used for the Bloom filter BF of structure m bit of m bit to send to data owner, be that data owner and Cloud Server generate public private key pair { (n ₁, e ₁), d ₁and { (n ₂, e ₂), d ₂;

Step 2, key generate (mk, T): Share (T, ac) algorithm is carried out at trusted authority center, and each leaf node of access tree T can obtain the part of relevant secret ac and share q _v(0),, to each leaf node v ∈ lvs (T), choose t ← Z _p, calculate and B _v=g ^t, note private key sk=(T, A _v, B _v) | v ∈ lvs (T));

Step 3, the encryption to keyword and file address: the hash function that (w, atts, ID (w)) data owner sends by trusted authority center generates Bloom filter, BF ← BFGen ({ H ₁' ..., H' _k, { w ₁..., w _l), to containing keyword w data file address ID _wand Bloom filter, SYM _enc() cryptographic algorithm is encrypted, and symmetric key is sk ₁:

BF _Enc＝SYM(BF),(ID _w) _Enc＝SYM(ID _w)；

User data owner is to BF _enc(ID _w) _encsign: $A={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|\mathrm{sig}\left({\mathrm{BF}}_{\mathrm{Enc}}\right)={\mathrm{BF}}_{\mathrm{Enc}}\left|\right|{\left({\mathrm{BF}}_{\mathrm{Enc}}\right)}^{d_1},B={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|\mathrm{sig}{\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}={\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\left|\right|{\left({\left({\mathrm{ID}}_w\right)}_{\mathrm{Enc}}\right)}^{d_1}$ To sk ₁by ABE () cryptographic algorithm, be encrypted: C=ABE (sk ₁);

After search finishes, the validated user that attribute meets access strategy just can be deciphered C and obtain sk ₁, and then file destination is obtained in deciphering;

Select r ₁, r ₂← Z _p, calculate $W^{\&prime;}=g^{{\mathrm{cr}}_1},W=g^{a(r_1+r_2)}{g}^{b{H}_2\left(w\right)r_1};$ F=(f ₁, f ₂) wherein $f_1=g^{a(r_1+r_2)},f_2=g^{{\mathrm{br}}_1},W_0=g^{r_2},$ To each at _j∈ Atts, calculates $W_j=H_1{\left({\mathrm{at}}_j\right)}^{r_2},$ With the PKI of server, W is encrypted and obtained $W_E=W^{e_2}={\left(g^{a(r_1+r_2)}{g}^{{\mathrm{bH}}_2\left(w\right)r_1}\right)}^{e_2},$ Can remember that like this ciphertext keyword is:

cph＝(Atts,W',W _E,W ₀,W _j,F,A,B,C)；

Step 4, generation search password (sk, w): select s ← Z _p, each leaf node v ∈ lvs (T) is calculated $A_v^{\&prime;}=A_v^s,B_v^{\&prime;}=B_v^s,$ Search password is ${\mathrm{tok}}_1={\left(g^a{g}^{{\mathrm{bH}}_2\left(w\right)}\right)}^s,$ Tok ₂=g ^cs, use the PKI of server to tok ₂be encrypted: note tk=(tok ₁, (tok ₂) _enc, T, (A' _v, B' _v) | v ∈ lvs (T));

Step 5, search (tk, cph): server is chosen the access tree that property set S meets appointment in search password from cph, if such S set does not exist, returns to 0; Otherwise, to each at _j∈ S, calculates $E_v=e(A_v^{\&prime;},W_0)/e(B_v^{\&prime;},W_j)=e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}\mathrm{att}\left(v\right)={\mathrm{at}}_j,v\&Element;\mathrm{lvs}\left(T\right),$ In conjunction with (T, E _v| att (v) ∈ S), calculate $e{(g,g)}^{{\mathrm{sr}}_2{q}_v\left(0\right)}=e{(g,g)}^{{\mathrm{sr}}_2{q}_{\mathrm{root}}\left(0\right)},$ And then $E_{\mathrm{root}}=e{(g,g)}^{{\mathrm{acsr}}_2}$ The private key deciphering W of oneself for server _e, (tok ₂) _encobtain W and tok ₂if, e (W', tok ₁) E _root=e (W, tok ₂), return W, F, A, B, C} is to user; Otherwise, only return to A;

Step 6, checking { W, F, A, B, C}: data user receives after the Search Results that Cloud Server returns, and carries out verification operation.

5. the PKI that effectively can verify based on KP-ABE as claimed in claim 1 can be searched for encryption method, it is characterized in that, the concrete grammar of described verification operation is:

The existence of step 1, searched key word: when data user only receives the A that Cloud Server returns, first with data owner's PKI, A is verified; If by checking; C is decrypted to operation and obtains symmetric key sk ₁, deciphering A obtains Bloom filter BF, if BFverify (w)=0 means the keyword that does not exist user to search on Cloud Server, otherwise rejection returns results;

The correctness of step 2, searched key word: data user receive W, F, A, B, during C}, calculates W/f ₁with if illustrate correctly, otherwise explanation is error result;

Step 3, the integrality of data file address that comprises keyword w: when data user has verified after the correctness of keyword, then B is verified, if by deciphering C, obtain sk ₁, and then obtain target data file.

6. the PKI that effectively can verify based on KP-ABE as claimed in claim 1 can be searched for encryption method, it is characterized in that, the described PKI that effectively can verify based on KP-ABE can be searched for being analyzed as follows of correctness of encryption method:

Step 1, search coupling correctness:

Cloud Server, after receiving data user's searching request, is carried out search operation.First by with RSA Algorithm, with the private key of oneself, ciphertext keyword and search password are decrypted, then, carry out following matching operation:

$\begin{array}{c}e(W^{\&prime;},{\mathrm{tok}}_1)E_{\mathrm{root}}={e(g^{{\mathrm{cr}}_1},\left(g^a{g}^{{\mathrm{bH}}_2\left(w\right)}\right))}^s=\\ e{(g,g)}^{\mathrm{acs}(r_1+r_2)}e{(g,g)}^{{\mathrm{bcsH}}_2\left(w\right)r_1};\end{array}$

$\begin{array}{c}e(W,{\mathrm{tok}}_2)={e\left(g^{a(r_1+r_2)}{g}^{{\mathrm{bH}}_2\left(w_1\right)r_1},g^{\mathrm{cs}})\right)}^s=\\ e{(g,g)}^{\mathrm{acs}(r_1+r_2)}e{(g,g)}^{{\mathrm{bcsH}}_2\left(w_1\right)r_1}.\end{array}$

If w and w ₁same keyword, e (W', tok so ₁) E _rootand e (W, tok ₂) be exactly what equate, illustrate and search for successfully;

Step 2, proving correctness:

When data user receive the Search Results that Cloud Server returns W, F, A, B, during C}, first will verify the correctness of keyword, finds f in F ₁, f ₂, do to calculate as follows:

$W/f_1=g^{a(r_1+r_2)}{g}^{b{H}_2\left(w\right)r_1}/g^{a(r_1+r_2)}=g^{{\mathrm{bH}}_2\left(w\right)r_1}$

The cryptographic Hash H of the keyword that user searches for oneself ₂(w ₁) be calculated as follows:

$f_2^{H_2\left(w_1\right)}=g^{{\mathrm{bH}}_2\left(w_1\right)r_1}$

If w and w ₁while being same keyword, W/f ₁with equate, illustrate, Search Results is correct, after this, carrys out correctness and the integrality of verification msg file address by signature.