Data protection method and data protection system

• US 8,539,606 B2
• Filed: 07/02/2012
• Issued: 09/17/2013
• Est. Priority Date: 08/12/2011
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Zhang, Gong
• Primary Examiner(s): HENNING, MATTHEW T
• Application Number:
  US13/540,288
• Publication Number:
  US 20130042113A1
• Time in Patent Office: 442 Days
• Field of Search: None
• US Class Current: 726/27
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 9/006 involving public key infrastructure [PKI] trust models network architecture or network communication protocol for supporting authentication of entities using certificates in a packet data network H04L63/0823
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/0827 involving distinctive intermediate devices or communication paths network architectures or network communication protocols using different networks H04L63/18
• CPC Class Codes: H04L 9/3013 involving the discrete logarithm problem, e.g. ElGamal or Diffie-Hellman systems
• CPC Class Codes: H04L 9/3073 involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing

Abstract

Present invention provides a data protection method, used by a data owner to share data with a data sharer securely through a data distribution system. The data owner first establishes a proxy relationship with the data sharer, while the data distribution system maintains a proxy relationship between the data owner and the data sharer, and after receiving encrypted shared data sent by the data owner, the data distribution system changes the encrypted shared data according to the proxy relationship, so that the data sharer may decrypt the data. By using the data protection method in the present invention, both encryption and decryption of data are a result of coordination of three parties, thereby avoiding a problem of data leakage caused by a problem of a single party.

Claims

1. A data protection method, comprising:

establishing, by a data owner, a proxy relationship with a data sharer, and generating a proxy relation f_AB according to a private key of the data owner sk_A and a public key of the data sharer pk_B;

sending, by the data owner, proxy relationship information and the proxy relation f_AB to a data distribution system, wherein the proxy relationship information comprises information about the proxy relationship established between the data owner and the data sharer;

updating, by the data distribution system, a proxy relationship table of the data owner according to the proxy relationship information, and establishing a mapping relationship between the proxy relation f_AB and the data sharer, wherein the proxy relationship table is used to record information about a data sharer establishing a proxy relationship with the data owner;

generating, by the data owner, a secret value m of shared data, and encrypting the shared data by using the secret value m;

encrypting, by the data owner and by using a public key of the data owner pk_A, the secret value m to obtain an upper-layer key;

sending, by the data owner, the shared data encrypted by the secret value m and the upper-layer key to the data distribution system;

after receiving the encrypted shared data and the upper-layer key, searching, by the data distribution system, the proxy relationship table and confirming the proxy relationship between the data owner and the data sharer, and when the data distribution system confirms that the proxy relationship is established between the data owner and the data sharer, obtaining, by the data distribution system, the proxy relation f_AB corresponding to the data sharer;

updating, by the data distribution system, the upper-layer key according to the proxy relation f_AB to obtain an updated upper-layer key;

sending, by the data distribution system, the encrypted shared data and the updated upper-layer key to the data sharer;

decrypting, by the data sharer and according to a private key of the data sharer sk_B, the updated upper-layer key to obtain the secret value m; and

decrypting, by the data sharer, the encrypted shared data according to the secret value m to obtain the shared data;

wherein;

the private key of the data owner is sk_A=(S_A1, S_A2), wherein S_A1 and S_A2 are two elements of the private key of the data owner;

the public key of the data owner is Pk_A=(P_A1, P_A2), wherein P_A1 and P_A2 are two elements of the public key of the data owner;

the private key of the data sharer is sk_B=(S_B1, S_B2), wherein S_B1 and S_B2 are two elements of the private key of the data sharer;

the public key of the data sharer is pk_B=(P_B1, P_B2), wherein P_B1 and P_B2 are two elements of the public key of the data sharer; and

S_A1=a₁, S_A2=a₂, P_A1=Z^a1, P_A2=g^a2, S_B1=b₁, S_B2=b₂, P_B1=Z^b1, and P_B2=g^b2, wherein a₁, a₂, b₁, and b₂ are all random numbers, a preset parameter g is a generator of a cyclic group G₁, Z is an element of a cyclic group G₂, G₂ is e;

G₁×

G₁→

G₂ obtained by G₁ through bilinear mapping, and Z=e(g, g);

wherein the establishing, by a data owner, a proxy relationship with a data sharer, and generating a proxy relation, and the sending, by the data owner, the proxy relation to a data distribution system comprise;

establishing, by the data owner, the proxy relationship with the data sharer, and generating multiple proxy relations, and sending, by the data owner, each relation in the multiple proxy relations to a corresponding data distribution system in multiple data distribution systems separately;

the updating, by the data distribution system, the upper-layer key according to the proxy relation to obtain an updated upper-layer key comprises;

updating, by each data distribution system and according to a proxy relation received by itself separately, the upper-layer key to obtain an updated upper-layer key;

the decrypting, by the data sharer and according to a private key of the data sharer, the updated upper-layer key to obtain the secret value m comprises;

obtaining, by the data sharer and according to multiple updated upper-layer keys generated by the multiple data distribution systems, a combined key; and

obtaining, by the data sharer and according to the combined key and the private key of the data sharer, the secret value m;

wherein the establishing, by the data owner, the proxy relationship with the data sharer, and generating multiple proxy relations, and the sending, by the data owner, each proxy relation in the multiple proxy relations to a corresponding data distribution system in multiple data distribution systems separately comprise;

according to the private key of the data owner and the public key of the data sharer and according to a formula

f_AB(i)=(P_B2)^ri; and

generating, by the data owner and the data sharer, the multiple proxy relations corresponding to the multiple data distribution systems in a one-to-one manner, wherein f_AB (i) indicates a proxy relation corresponding to an i^th data distribution system, and Σ

_i=1^Tr_i=S_A1, wherein T is the number of the multiple data distribution systems.

2. The data protection method according to claim 1, wherein the encrypting, by the data owner and by using a public key of the data owner, the secret value m to obtain an upper-layer key comprises:

performing public key encryption on the secret value m by using the public key of the data owner (P_A1,P_A2) to obtain an upper-layer key (g^k, m(P_A1)^k), wherein k is a random number; and

the updating, by the multiple data distribution systems and according to the multiple proxy relations, the upper-layer key to obtain multiple updated upper-layer keys comprises;

updating, by the i^th data distribution system and according to the proxy relation f_AB(i)=(P_B2)^ri, the upper-layer key (g^k, m(P_A1)^k) to obtain an updated upper-layer key (e(g^k, f_AB(i)), m(P_A1)^k) of the i^th data distribution system.

3. The data protection method according to claim 1, wherein the combined key is

(Π

_i=1^Te(g^k, f_AB(i)), m(P_A1)^k), and the obtaining, according to the combined key, the secret value m comprises;

solving the secret value m according to a formula

4. A data sharing system, comprising:

a data owner,

a data distribution system,

a data sharer,

wherein the data owner distributes shared data to the data sharer through the data distribution system;

the data owner comprises a proxy relationship establishing module, a key generating module, and a shared data sending module;

the data distribution system comprises a receiving module, a proxy relationship maintaining module, an upper-layer key updating module, and a shared data distributing module;

the data sharer comprises an obtaining module and a decrypting module, wherein;

the proxy relationship establishing module is configured to establish a proxy relationship with the data sharer, generate a proxy relation f_AB according to a private key of the data owner sk_A and a public key of the data sharer pk_B, and send proxy relationship information and the proxy relation f_AB to the data distribution system, wherein the proxy relationship information comprises information about the proxy relationship established between the data owner and the data sharer;

the key generating module is configured to generate a secret value m of the shared data, encrypt the shared data by using the secret value m, and encrypt the secret value m by using a public key of the data owner pk_A to obtain an upper-layer key;

the shared data sending module is configured to send encrypted shared data and the upper-layer key to the data distribution system;

the receiving module is configured to obtain the proxy relationship information, the proxy relation, the encrypted shared data, and the upper-layer key that are from the data owner;

the proxy relationship maintaining module is configured to update a proxy relationship table of the data owner according to the proxy relationship information, and establish a mapping relationship between the proxy relation f_AB and the data sharer, and when the receiving module receives the encrypted shared data and the upper-layer key, the proxy relationship maintaining module is further configured to search the proxy relationship table and confirm the proxy relationship between the data owner and the data sharer, and obtain the proxy relation f_AB corresponding to the data sharer when confirming that the proxy relationship is established between the data owner and the data sharer, wherein the proxy relationship table is used to record information about a data sharer establishing a proxy relationship with the data owner;

the upper-layer key updating module is configured to update the upper-layer key according to the proxy relation to obtain an updated upper-layer key;

the distributing module is configured to send the shared data and the updated upper-layer key to the data sharer;

the obtaining module is configured to receive the shared data and the updated upper-layer key that are from the data distribution system; and

the decrypting module is configured to decrypt the updated upper-layer key according to a private key of the data sharer sk_B to obtain the secret value m;

wherein;

the private key of the data owner is sk_A=(S_A1, S_A2) , wherein S_A1 and S_A2 are two elements of the private key of the data owner;

the public key of the data owner is pk_A=(P_A1, P_A2), wherein P_A1 and P_A2 are two elements of the public key of the data owner;

the private key of the data sharer is sk_B=(S_B1, S_B2), wherein S_B1 and S_B2 are two elements of the private key of the data sharer;

the public key of the data sharer is pk_B=(P_B1, P_B2), wherein P_B1 and P_B2 are two elements of the public key of the data sharer; and

S_A1=a₁, S_A2=a₂, P_A1=Z^a1, P_A2=g^a2, S_B1=b₁, S_B2=b₂, P_B1=Z^b1, and P_B2=g^b2, wherein a₁, a₂, b₁, and b₂ are all random numbers, a preset parameter g is a generator of a cyclic group G₁, Z is an element of a cyclic group G₂, G₂ is e;

G₁×

G₁→

G₂ obtained by G₁ through bilinear mapping, and Z=e(g, g);

wherein;

the data sharing system comprises multiple data distribution systems;

the data owner distributes data to the data sharer through the multiple data distribution systems; and

the proxy relationship establishing module generates multiple proxy relations according to f_AB(i)=(P_B2)^ri, and sends the multiple proxy relations to the multiple data distribution systems separately, wherein f_AB(i) indicates a proxy relation sent to an i^th data distribution system, and Σ

_i=1^Tr_i=S_A1, wherein T is the number of the multiple data distribution systems.

5. The data sharing system according to claim 4, wherein:

the key generating module performs public key encryption on the secret value m by using the public key of the data owner (P_A1,P_A2) to obtain an upper-layer key (g^k, m(P_A1)^k), wherein k is a random number; and

the upper-layer key updating module updates the upper-layer key (g^k, m(P_A1)^k), according to the proxy relation f_AB(i)=(P_B2)^ri to obtain an updated upper-layer key (e(g^k, f_AB(i)), m(P_A1)^k) of the i^th data distribution system.

6. The data sharing system according to claim 5, wherein:

the decrypting module obtains a combined key (Π

_i=1^Te(g^k, f_AB(i)), m(P_A1)^k) according to the updated upper-layer key (e(g^k, f_AB(i)), m(P_A1)^k) obtained from the multiple data distribution systems, and the decrypting module obtains the secret value m

7. The data sharing system according to claim 4, wherein:

the data owner further comprises a key updating module, configured to update the private key of the data owner and the public key of the data owner, wherein the key updating module generates a second private key of data owner (S_A1′

, S_A2′

) and a second public key of the data owner (P_A1′

, P_A2′

) and calculates an update coefficient t₁=S_A1′

/S_A1, and the data owner is further configured to send the update coefficient t₁=S_A1′

/S_A1 to the data distribution system; and

the data distribution system further comprises a key update responding module, configured to update the proxy relation, namely, f_AB′

(f_AB)^t1, or f_AB′

(i)=(f_AB(i))^t1 according to the update coefficient.