CN104735070A - Universal data sharing method for heterogeneous encryption clouds - Google Patents

Abstract

The invention discloses a general data sharing method among heterogeneous encrypted clouds, belonging to the technical field of computer security. The invention includes: data sharing in encrypted cloud storage systems and data sharing among heterogeneous encrypted cloud storage systems. For data sharing in the system, the data is encrypted with the session key, and then the session key is encrypted with the private key of the sender. The cloud uses the re-encryption key authorized by the user to re-encrypt the session key, and finally the data ciphertext and the re-encryption ciphertext sent to the recipient. For data sharing between systems, first bind temporary identities for users in non-sender systems, and generate corresponding temporary public-private key pairs, and then generate corresponding re-encrypted ciphertexts according to the sharing steps in the system, and then encrypt with the public key of the receiver Temporary private key, and then send the encrypted temporary private key, re-encrypted ciphertext and data ciphertext to the recipient, the recipient decrypts with its own private key to obtain the temporary private key, then decrypts with the temporary private key to obtain the session key, and finally Decrypt with session key.

Description

A general data sharing method among heterogeneous encrypted clouds

technical field

The invention belongs to the technical field of computer security, and more specifically relates to a general data sharing method among heterogeneous encryption clouds.

Background technique

In the existing cloud storage technology, data is stored in the cloud which cannot be controlled by the user. In order to protect the security and privacy of sensitive data, data encryption is usually used to protect the security of the data. Commonly used symmetric encryption schemes have security problems. Among them, there is only one key for encrypting data, and both the sending and receiving parties use the same key to encrypt and decrypt the data. This requires the decrypting party to know the encryption key in advance, so that the key The security cannot be guaranteed, so the symmetric encryption system is not suitable for distributed file storage system. Therefore, in order to ensure the confidentiality and privacy of cloud data, encrypted cloud storage systems usually need to use public key cryptography (asymmetric encryption) to encrypt user data. At present, there are many types of public key cryptosystems, the mainstream ones are Certificate-Based Encryption (CBE for short), Identity-Based Encryption (IBE for short), and Attribute-Based Encryption (Attribute-Based Encryption, ABE for short) and Certificateless Encryption (CLE for short).

Proxy re-encryption (proxy re-encryption, hereinafter referred to as PRE) is a conversion mechanism between ciphertexts, which was proposed by Blaze et al. The formal definition of the specification was given at the Distributed System Security Symposium and the 2007 ACM Computer and Communication Security Conference. In PRE, a semi-trusted agent converts the ciphertext encrypted with the public key PKA of the authorizer A to the encrypted text encrypted with the public key PKB of the authorized person (Delegate) B through the conversion key RK generated by the agent A. In this process, the agent cannot obtain the plaintext information of the data, thereby reducing the risk of data leakage. The plaintexts corresponding to the two ciphertexts are the same, so that data sharing between the authorizer A and the authorized person B is realized. The application of PRE in the cloud storage system can improve the flexibility of users to share data on the premise of ensuring the security and privacy of user data. PRE is an extension of the public key encryption system, so there are many types of corresponding PRE, such as CB-PRE, IB-PRE, AB-PRE and CL-PRE.

Different cloud storage systems are likely to adopt different PRE schemes, so it will be very convenient for users within the system to share data, but there will be problems in data sharing between different PRE encrypted cloud storage systems. Since the ciphertexts between different PRE schemes are generally not interchangeable, there is a problem of data sharing in heterogeneous systems. For the ciphertext conversion between different public key encryption systems, there are some technologies trying to solve this problem. In 2007, Matsuo proposed the concept of hybrid proxy re-encryption in the article "Proxyre-encryption systems for identity-based Encryption", and the solution proposed in his article solved the ciphertext conversion from ElGamal type CBE to BB-IBE. Following Matsuo's scheme, there is a hybrid proxy re-encryption scheme from IBE to CBE, ABE to IBE, and CLE to CBE. This kind of hybrid proxy re-encryption scheme can make it easier to share ciphertext between systems using different public key encryption schemes or different schemes of the same system. However, the existing methods or technologies are all aimed at converting specific and special encryption schemes, and all of them need to make more or less changes to the original encrypted cloud storage system, which cannot completely solve the existing heterogeneous encrypted cloud storage. There is a problem of sharing ciphertext between systems, and it cannot be deployed well in practical applications.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a general data sharing method among heterogeneous encryption clouds to realize the sharing of ciphertext among various types of encryption clouds. The present invention adopts the method of temporary public and private keys to realize the proxy re-encryption scheme of the ciphertext data between general heterogeneous encrypted cloud storages. The heterogeneous encrypted cloud storages may apply different types of encryption systems or the same encryption system but Different password schemes, and the changes to the original encrypted cloud system are minimized, thereby improving the practicality.

The present invention provides a general data sharing method among heterogeneous encrypted clouds, comprising the following steps:

Step 1. The two heterogeneous encryption cloud systems α and β respectively run their system initialization algorithms to generate corresponding public parameter and secret parameter pairs (MP _α , MS _α ) and (MP _β , MS _β ), where MP represents the main Public parameters; MS represents the master secret parameter; and selects the symmetric encryption algorithm (K, SE, SD) as the user data encryption algorithm, wherein K represents the symmetric key space; SE and SD represent the symmetric encryption and decryption algorithms respectively;

The respective key generation centers of the α and β systems described in step 2 distribute public-private key pairs (PK, SK) to users within the system, where PK represents the public key of the user; SK represents the private key of the user;

In step 3, the first user in the β system generates a session symmetric key k for the plaintext data M, runs a symmetric encryption algorithm to encrypt the plaintext data M to obtain ciphertext data C _A,1 , and runs an encryption algorithm to generate the session symmetric key The key ciphertext _{CA, 2} corresponding to k, and then upload the ciphertext data _{CA, 1} and the key ciphertext CA _{, 2} to cloud storage;

Step 4 judges whether the ciphertext data _{CA, 1} is self-acquiring or shared, if the first user in the β system accesses the ciphertext data _{CA, 1,} then perform step 5, otherwise perform step 6;

In step 5, the first user in the β system downloads the ciphertext data C _A,1 and the key ciphertext C _A,2 from the cloud, runs a decryption algorithm to obtain the session symmetric key k, and then runs The symmetric decryption algorithm decrypts the ciphertext data _CA,1 to obtain the plaintext data M;

Step 6: judging whether the receiver and the first user in the β system are in the same system, if so, execute step 7, otherwise execute step 8;

The first user in the β system described in step 7 first runs the re-encryption key generation algorithm to generate a re-encryption key and send it to the cloud; then run the re-encryption algorithm on the cloud to generate the re-encryption key ciphertext _C'A ; the recipient retrieves the shared data of the first user in the β system from the cloud ( _{CA, 1} , _C'A ), run the re-encrypted ciphertext decryption algorithm to obtain the session symmetric key k, and then run the symmetric decryption algorithm to decrypt the ciphertext data _{CA, 1} to obtain the plaintext data M;

Step 8: If the recipient is the first user in the α system, generate a temporary public-private key (PK _t , SK _t ) for the first user in the α system and generate an inter-system re-encryption key Among them, PK _t represents the temporary public key; SK _t represents the temporary private key;

In step 9, the cloud analyzes the inter-system re-encryption key get temporary re-encryption key Run the re-encryption algorithm to obtain the re-encryption key ciphertext C', and send the inter-system re-encryption ciphertext {C', C _α } to the first user in the α system;

In step 10, the first user in the α system obtains the re-encrypted ciphertext {C', C _α }, first parses to obtain the temporary key ciphertext C _α , and runs the decryption algorithm of the α system to obtain the temporary private key key SK _t , and then run the re-encryption ciphertext decryption algorithm of the β system to obtain the session symmetric key k, and finally run the symmetric decryption algorithm to decrypt the ciphertext data _CA,1 to obtain the plaintext data M.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

(1) The versatility of heterogeneous encrypted cloud data sharing. When this scheme is applied to the existing system, no matter what kind of proxy re-encryption scheme is adopted by the system, when the user needs to securely share its data with the external users of the system, as long as the receiving user’s system adopts the public key cryptosystem, This data sharing operation can be realized;

(2) The convenience of program deployment. Since this technical solution does not need to modify the parameters or data in the original running system when expanding the original PRE encrypted storage system, it maintains the advantages of the original proxy encrypted cloud storage system to the greatest extent, so when deploying this technology It is very convenient when planning.

Description of drawings

Fig. 1 is the flowchart of the data sharing method among general heterogeneous encrypted clouds of the present invention;

Fig. 2 is an interactive flow chart of inter-system re-encryption key generation in 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. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Fig. 1 shows the flow chart of the data sharing method among general heterogeneous encrypted clouds of the present invention, specifically comprises the following steps:

Step 1 System initialization. In the embodiment of the present invention, there are two encryption cloud systems α, β, wherein, system α adopts the certificateless proxy re-encryption scheme CL-PRE, for example, by the algorithm (Setup _α , PartialSKGen _α , PKGen _α , SKGen _α , Enc _α , Dec-1 _α , RK _α , ReEnc _α , Dec-2 _α ), each algorithm is program initialization, partial private key generation, public key generation, private key generation, encryption, original decryption, re-encryption key generation , re-encryption, and re-encryption ciphertext decryption; system β, for example, adopts the identity-based proxy re-encryption scheme IB-PRE, by the algorithm (Setup _β , Extrac β , Enc _{β ,} Dec-1 _β , RK _β , ReEnc _β , Dec- 2 _β ), each algorithm is scheme initialization, key generation, encryption, original decryption, re-encryption key generation, re-encryption, and re-encryption ciphertext decryption. The two systems α and β each run the system initialization algorithm (such as the Setup(1 ^k ) algorithm) and generate corresponding public and secret parameter pairs (MP _α , MS _α ) and (MP _β , MS _β ), respectively, where MP Indicates the main public parameter; MS indicates the main secret parameter; and selects the symmetric encryption algorithm (K, SE, SD) as the user data encryption algorithm, where K represents the symmetric key space; SE and SD represent the symmetric encryption and decryption algorithms respectively.

Step 2 key distribution. The respective Key Generation Centers (Key Generating Center, hereinafter referred to as KGC) of the α and β systems run the Extrac (MP _x , MS _x , aux _x ) algorithm to distribute public-private key pairs (PK, SK) to users within the system, where PK Represents the user's public key; SK represents the user's private key; aux is the user's auxiliary information (for example: identity information, attribute information, random numbers for traditional proxy re-encryption, etc.); x={α, β}. The details are as follows: User A submits his identity information ID _A as a public key to KGC _β , the key distribution organization of the system β, and KGC _β runs the Extrac _β algorithm to generate a private key SK _A for him, then his public-private key pair is (ID _A , SK _A ). Similarly, user B in the β system obtains its public-private key pair (ID _B , SK _B ). User C submits his identity information ID _C to the key distribution organization KGC α of the system _α , and KGC _α runs the algorithm PartialSKGen _α to generate a partial private key DK _c , and user C selects an algebraic structure determined by the main public parameter MP _α Run the algorithm PKGen _α and SKGen _α respectively to generate the public-private key pair (PK _C , SK _C ) by combining the random number r in the identity information ID _C and the partial private key DK _c .

Step 3 encrypt data and upload. User A wants to upload the plaintext data M to the cloud, firstly generate a session symmetric key k for the plaintext data M, run the symmetric encryption algorithm SE(k, M) to obtain the ciphertext data C _{A, 1} , run the encryption algorithm Enc(MP _β , ID _A , k) Generate the key ciphertext CA _{, 2} corresponding to the session symmetric key k, and then upload the ciphertext data CA _{, 1} and the key ciphertext _{CA, 2} to the cloud storage.

Step 4 judges whether the ciphertext data _{CA, 1} is self-collected or shared. If user A accesses the ciphertext data by himself, go to step 5, otherwise go to step 6, that is, share the data with others.

Step 5: Download and decrypt the ciphertext data _{CA, 1} and key ciphertext _{CA, 2} . If user A needs to use plaintext data M, download ciphertext data C _{A, 1} and key ciphertext C _{A, 2} from the cloud, and then run the decryption algorithm Dec-1 _β (MP _β , SK _A , C _{A, 2} ) Get the session symmetric key k, and then run the symmetric decryption algorithm SD(k, CA _{, 1} ) to get the plaintext data M.

Step 6 judges whether the receiver and the sender (namely user A) are in the same system, if the receiver and the sender are in the same system, go to step 7, otherwise go to step 8, that is, share it with users outside the system.

Step 7 Share the internal users of the system. User A wants to share the data stored in the cloud with user B in the same system. User A first runs the re-encryption key generation algorithm RK _β (MP _β , PK _B , SK _A ) to generate a re-encryption key and send it to the cloud; then run the re-encryption algorithm ReEnc _β ( C _{A, 2} ) Generate re-encryption key ciphertext C'_A; user B retrieves user A's shared data (C _{A, 1} , C' _A ) from the cloud, and runs re-encryption ciphertext decryption algorithm Dec-2 _β ( MP _β , SK _B , C' _A ) to obtain the session symmetric key k, and then run the symmetric decryption algorithm SD(k, CA _{, 1} ) to obtain the plaintext data M.

Step 8. User A wants to share data with user C in the α system. The process of generating temporary public and private keys for user C is shown in Figure 2, which specifically includes the following sub-steps:

(8-1) User A first randomly selects a temporary auxiliary information Aux _t to identify the temporary user. Specifically, it is the identity information ID _t in the β system, which is sent to the KGC _β of the β system;

(8-2) KGC _β runs the key generation algorithm Extrac _β (MP _β , MS _β , ID _t ) to generate a corresponding temporary public-private key (PK _t , SK _t ) for the identity information and sends it to user A, where PK _t represents the temporary public key; SK _t represents the temporary private key;

(8-3) User A runs the re-encryption key generation algorithm RK _β (MP _β , PK _t , SK _A ) to generate a temporary re-encryption key

(8-4) User A runs the encryption algorithm Enc _α (MP _α , PK _C , SK _t ) of the α system to encrypt the temporary private key to obtain the temporary key ciphertext C _α ;

(8-5) Re-encrypt the key between systems sent to the cloud.

Step 9 Cloud analysis inter-system re-encryption key get temporary re-encryption key Run the re-encryption algorithm ReEnc _β ( C _{A, 2} ) Obtain the re-encryption key ciphertext C', and send the inter-system re-encryption ciphertext {C', C _α } to user C.

Step 10 User C obtains the inter-system re-encrypted ciphertext {C', C _α }, first parses to obtain the temporary key ciphertext C _α , and runs the decryption algorithm Dec-1 _α (MP _α , SK _C , C _α ) to obtain the temporary private key SK _t , and then run the re-encrypted ciphertext decryption algorithm Dec-2 _β (MP _β , SK _t , C') of the β system to obtain the session symmetric key k, and finally run the symmetric decryption algorithm SD(k, C _{A, 1} ) Obtain plaintext data M.

Proxy re-encryption schemes in the present invention include but are not limited to listed types: traditional PKI-based proxy re-encryption PKI-PRE, identity-based proxy re-encryption IB-PRE, attribute-based proxy re-encryption AB-PRE and Certificateless proxy re-encryption based on CL-PRE. The two heterogeneous proxy re-encryption schemes adopted by the α and β systems can be all combinations of the above-mentioned types of schemes; it also includes all combinations of different instantiation schemes in the same type. The instantiation scheme is the calculation of each algorithm The specific type scheme of the details; it also includes all combinations of the same instantiation scheme but using different security parameters and public parameters. The implementation scheme is the instantiation scheme of the security parameters and public parameters.

The present invention can be extended to data security sharing from PRE encrypted cloud storage to PKE encrypted cloud storage. That is, users in the PRE encrypted cloud storage system can safely share their data with another user in the PKE encrypted cloud storage system that is heterogeneous with PRE, and vice versa. The PRE scheme is a functional extension of PKE, and the scheme in α in the above embodiment can be replaced with the PKE encryption scheme. At this time, the heterogeneity of PRE and PKE is represented by: different key schemes are adopted in the key generation algorithm, or the same key scheme is adopted, but different security parameters and public parameters are used.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (3)

1. general isomery adds the data sharing method between Miyun, it is characterized in that, comprising:

Step 1 two its system initialization algorithms of each self-operating of isomery encryption cloud system α, β, generate corresponding openly parameter, secret parameter respectively to (MP _α, MS _α) and (MP _β, MS _β), wherein, MP represents that Your Majesty opens parameter; MS represents main secret parameter; And choose symmetric encipherment algorithm (K, SE, SD) as ciphering user data algorithm, wherein, K represents symmetric key space; SE and SD represents symmetric cryptography and decipherment algorithm respectively;

α, beta system key generation centre separately described in step 2 is that the user of its internal system distributes public private key pair (PK, SK), and wherein, PK represents the PKI of user; SK represents the private key of user;

In beta system described in step 3, first user is that clear data M generates session symmetric key k, and operation symmetric encipherment algorithm is encrypted described clear data M and obtained encrypt data C _{a, 1}, run cryptographic algorithm and generate key ciphertext C corresponding to described session symmetric key k _{a, 2}, then by described encrypt data C _{a, 1}with described key ciphertext C _{a, 2}be uploaded to high in the clouds to store;

Step 4 judges described encrypt data C _{a, 1}ask for or share, if first user oneself takes described encrypt data C in described beta system _{a, 1}then perform step 5, otherwise perform step 6;

In beta system described in step 5, first user downloads described encrypt data C from described high in the clouds _{a, 1}with described key ciphertext C _{a, 2}, run decipherment algorithm and obtain described session symmetric key k, the symmetrical decipherment algorithm that reruns deciphers described encrypt data C _{a, 1}obtain described clear data M;

Step 6 to judge in recipient and described beta system first user whether in same system, if then perform step 7, otherwise performs step 8;

In beta system described in step 7, first first user runs re-encrypted private key generating algorithm and generates re-encrypted private key RK _{β, A → B}, and send it to described high in the clouds; Run re-encryption algorithm by described high in the clouds again and generate re-encrypted private key ciphertext C ' _a; Described recipient fetches the shared data (C of first user in described beta system from described high in the clouds _{a, 1}, C ' _a), run re-encryption decrypt ciphertext algorithm and obtain described session symmetric key k, the symmetrical decipherment algorithm that reruns deciphers described encrypt data C _{a, 1}obtain described clear data M;

If step 8 recipient is first user in described α system, for first user in described α system generates interim public and private key (PK _t, SK _t) and re-encrypted private key RK between generation system _{a → C}, wherein, PK _trepresent temporary public key; SK _trepresent temporary private;

Re-encrypted private key RK between described system is resolved in high in the clouds described in step 9 _{a → C}obtain interim re-encrypted private key RK _{β, A → PKt}, run re-encryption algorithm and obtain re-encrypted private key ciphertext C ', by re-encryption ciphertext between system C ', C _αsend to first user in described α system;

In α system described in step 10 first user get described re-encryption ciphertext C ', C _α, first resolve and obtain temporary key ciphertext C _α, the decipherment algorithm running described α system obtains described temporary private SK _t, the re-encryption decrypt ciphertext algorithm of the described beta system that reruns obtains described session symmetric key k, finally runs symmetrical decipherment algorithm and deciphers described encrypt data C _{a, 1}obtain described clear data M.

2. the method for claim 1, is characterized in that, in described step 2, the user in described beta system is to the cipher key distribution mechanism KGC of described system β _βsubmit the identity information ID of oneself to _aas PKI, the cipher key distribution mechanism KGC of described system β _βfor it generates private key SK _a, then its public private key pair is (ID _a, SK _a); The intrasystem user of described α is to the cipher key distribution mechanism KGC of described system α _αsubmit the identity information ID of oneself to _c, the cipher key distribution mechanism KGC of described system α _αfor its generating portion private key DK _c, the intrasystem user of described α chooses a Your Majesty again and opens parameter MP _αrandom number r in the Algebraic Structure determined is in conjunction with described identity information ID _cwith described part private key DK _cgenerate public private key pair (PK _c, SK _c).

3. method as claimed in claim 1 or 2, it is characterized in that, described step 8 comprises following sub-step:

(8-1) the supplementary Aux that in described beta system, first user random selecting one is interim _tto identify casual user, send it to the key generation centre KGC of described beta system _β;

(8-2) the key generation centre KGC of described beta system _βrunning key schedule is described interim supplementary Aux _tgenerate corresponding interim public and private key (PK _t, SK _t) and send to first user in described beta system;

(8-3) in described beta system, first user runs re-encrypted private key generating algorithm and generates interim re-encrypted private key RK _{β, A → PKt};

(8-4) in described beta system, first user runs the cryptographic algorithm of described α system by described temporary private SK _tencryption obtains temporary key ciphertext C _α;

(8-5) by re-encrypted private key RK between described system _{a → C}={ RK _{β, A → PKt}, C _αsend to described high in the clouds.