CN102034061A - Cryptographic algorithm homogeneity-based data possession proving method - Google Patents

Abstract

A data possession proof method based on cryptographic algorithm homomorphism, the purpose is to verify whether the untrusted storage server holds the data owner's data correctly, and prevent the storage service provider from deleting or tampering with the data. The technical solution is that before the data owner stores the data in the storage server, the data owner uses a cryptographic algorithm with homomorphism to calculate the label for the data block, and then stores the data block and its label in the storage server. When performing a data holding check, the data owner randomly selects some data blocks, and the storage server returns the sum of the data blocks requested by the data owner and the sum of their labels. Due to homomorphism, the data owner can It is consistent with the sum of tags to verify whether the storage server holds the data correctly. During the life cycle of data, data owners can regularly or irregularly verify whether their data is correct or not. Applicable to any storage system that stores data on untrusted storage servers.

Description

Data Possession Proof Method Based on Cryptographic Algorithm Homomorphism

technical field

The invention belongs to the field of computer storage technology, and specifically relates to a method for proving data possession based on cryptographic algorithm homomorphism. When a user stores data on an untrusted storage server, he is most concerned about whether the data is still correct Yes, the method proposed by the present invention can allow users to regularly or irregularly verify whether their data is still correctly stored on the server of the service provider, and is applicable to any storage system that stores data on untrusted storage servers.

Background technique

Outsourced storage services or cloud storage services can achieve any location, any time, any data access and ensure compliance with laws and regulations. For users who have unpredictable storage requirements and need cheap storage, outsourcing storage services or cloud storage services that purchase storage capacity on demand will obviously bring more convenience and benefits than purchasing a complete storage system at one time, and the external Purchasing storage services or cloud storage services not only saves investment for users, but also saves social resources and energy. However, because there are still many problems to be solved urgently in the security, reliability and service level of outsourced storage services or cloud storage services, they have not been widely used by people. When users store data in outsourced storage services or servers of cloud storage service providers, they are most concerned about whether their data is correct or not. Only when users are sure that their data is still complete and correct, can they use outsourced storage services or cloud storage services with confidence.

All currently known asymmetric encryption algorithms and some hash functions are homomorphic. There are two kinds of homomorphism, one is homomorphism for multiplication, that is, for cryptographic algorithm E, there is E(a*b)=E(a)*E(b), where * represents multiplication operation; the other is It is homomorphic to addition, that is, E(a+b)=E(a)+E(b), where + represents addition. In this paper, a cryptographic algorithm refers to any cryptographic algorithm that is homomorphic to addition.

Contents of the invention

The present invention proposes a data possession proof method based on cryptographic algorithm homomorphism, with the purpose of verifying whether an untrustworthy storage server still holds the user's data correctly, and preventing the storage service provider from deleting or tampering with the data.

The data possession proof method of the present invention comprises the following steps:

In the first step, the data owner calculates a label t _i =E _sk (d _i ) for each data block d _i , where E _sk ( ) is the encryption or signature operation of the cryptographic algorithm, and sk is the secret key;

In the second step, the data owner stores all data blocks <d _i , t _i > on the storage server;

In the third step, the data owner randomly selects c data blocks d _i1 , d _i2 , … d _ic , and requests the storage server to return the data holding evidence;

In the fourth step, the storage server fetches the data blocks d _i1 , d _i2 , … d _ic and their tags t _i1 , t _i2 , … t _ic requested by the data owner, and calculates the sum D of the data blocks and the sum T of their tags, namely D=d _i1 +d _i2 +…+d _ic , T=t _i1 +t _i2 +…+t _ic , send D and T to the data owner;

In the fifth step, the data owner uses the secret key sk to calculate E _sk (D) for the sum D of the data block. Because of the homomorphism of the cryptographic algorithm, E _sk (D)=E _sk (d _i1 +d _i2 + …+d _ic )=E _sk (d _i1 )+E _sk (d _i2 )+…+E _sk (d _ic )=t _i1 +t _i2 +…+t _ic ;

In the sixth step, the data owner judges whether E _sk (D) is equal to T sent by the storage server. If they are equal, it means that the storage server holds the data correctly; otherwise, it means that the data is destroyed.

A cryptographic algorithm refers to any cryptographic algorithm that is homomorphic to addition.

The method for proving data possession in the present invention can allow the data owner to verify whether the storage server still holds its data correctly.

Description of drawings

FIG. 1 is a relationship diagram of various entities involved in the present invention.

Fig. 2 is a flowchart of the present invention.

Detailed ways

As shown in Figure 1, before storing the data in the storage server 5, the data owner 9 uses the homomorphic encryption algorithm to calculate the label _{t i for} all data blocks d i, and then passes the data and its labels <d _i , t _i > through 2 is stored in the storage server 5, and the storage server 5 saves the data. Then the data owner 9 can regularly or aperiodically verify whether the storage server still holds its data correctly. When performing the holding check, the data owner 9 randomly selects c data blocks, and requires the storage server 5 to return the holding evidence through 1, and the storage server 5 calculates D=d _i1 +d _i2 +...+d _ic , T=t _i1 +t _i2 +…+t _ic , send D and T to the data owner 9 via 1. Due to the homomorphism of the cryptographic algorithm for calculating tags, the data owner 9 can use its secret key to calculate E _sk (D), and judge whether it is equal to the T sent by the storage server 5, which means that the storage server 5 holds its data correctly , otherwise the data is corrupted.

As shown in Figure 2, the concrete process of the present invention is:

In the first step, the data owner calculates a label t _i =E _sk (d _i ) for each data block d _i ;

In the second step, the data owner stores all data blocks <d _i , t _i > on the storage server;

In the third step, the data owner randomly selects c data blocks and requests the storage server to return data holding evidence;

In the fourth step, the storage server takes out the data blocks d _i1 , d _i2 , ...d _ic requested by the data owner and their tags t _i1 , t _i2 , ...t _ic , and calculates D=d _i1 +d _i2 +...+d _ic , T=t _i1 +t _i2 +…+t _ic , send D and T to the data owner;

In the fifth step, the data owner uses the secret key sk to calculate E _sk (D), because of the homomorphism of the cryptographic algorithm, E _sk (D)=E _sk (d _i1 +d _i2 +…+d _ic )= E _sk (d _i1 )+E _sk (d _i2 )+…+E _sk (d _ic )=t _i1 +t _i2 +…+t _ic ;

In the sixth step, the data owner judges whether E _sk (D) is equal to T sent by the storage server. If they are equal, it means that the storage server holds the data correctly; otherwise, it means that the data is destroyed.

Claims (2)

1. A data possession proof method based on cryptographic algorithm homomorphism, characterized in that it comprises the following steps: In the first step, the data owner calculates a label t _i =E _sk (d _i ) for each data block d _i , where E _sk () is the encryption or signature operation of the cryptographic algorithm, and sk is the secret key; In the second step, the data owner stores all data blocks <d _i , t _i > on the storage server; In the third step, the data owner randomly selects c data blocks and requests the storage server to return data holding evidence; In the fourth step, the storage server takes out the data blocks d _i1 , d _i2 , ...d _ic requested by the data owner and their tags t _i1 , t _i2 , ...t _ic , and calculates D=d _i1 +d _i2 +...+d _ic , T=t _i1 +t _i2 +…+t _ic , send D and T to the data owner; In the fifth step, the data owner uses the secret key sk to calculate E _sk (D), because of the homomorphism of the cryptographic algorithm, E _sk (D)=E _sk (d _i1 +d _i2 +…+d _ic )= E _sk (d _i1 )+E _sk (d _i2 )+…+E _sk (d _ic )=t _i1 +t _i2 +…+t _ic ; In the sixth step, the data owner judges whether E _sk (D) is equal to T sent by the storage server. If they are equal, it means that the storage server holds the data correctly; otherwise, it means that the data is destroyed. 2. A method for proving data possession based on cryptographic algorithm homomorphism according to claim 1, characterized in that said cryptographic algorithm refers to any cryptographic algorithm that is homomorphic to addition.

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