US-12625975-B2 - Secure secret sharing storage system using cloud service

US12625975B2US 12625975 B2US12625975 B2US 12625975B2US-12625975-B2

Abstract

A secret sharing storage system includes at least one user terminal, n units (n: an integer of 2 or more) of storage devices, and a main controller that is communicably connected to a random number generator. The main controller acquires a random number generated by the random number generator in a case of receiving original data sent from the user terminal, executes distributed processing on the original data by using the random number to generate n pieces of distributed data, and stores the n pieces of distributed data respectively in the corresponding n units of storage devices.

Inventors

Masakatsu Matsuo
Katsunori KOGATA
Masahide Sasaki
Mikio Fujiwara

Assignees

PANASONIC CORPORATION
NATIONAL INSTITUTE OF INFORMATION AND COMMUNICATIONS TECHNOLOGY

Dates

Publication Date: 20260512
Application Date: 20200121
Priority Date: 20190222

Claims (6)

1 . A secret sharing storage system, comprising: at least one user terminal; n units of storage devices, n being an integer of 2 or more, each storage device of the n units of storage devices including a first processor, a first memory, a first recording device, and a first communication circuit; n units of controllers that correspond respectively to the n units of storage devices, each controller of the n units of controllers including a second processor, a second memory, a second recording device, and a second communication circuit; and a main controller that is communicably connected to a random number generator and to the n units of controllers, wherein the main controller acquires a random number generated by the random number generator in a case of receiving original data sent from the user terminal, executes distributed processing on the original data by using the random number to generate n pieces of distributed data, generates logical distributed information relating to generation of the n pieces of distributed data, transmits the n pieces of distributed data and the logical distributed information to the n units of controllers in a first associated manner, and deletes the random number and the original data after transmitting the n pieces of distributed data and the logical distributed information to the n units of controllers in the first associated manner, wherein the n units of controllers receive the n pieces of distributed data and the logical distributed information from the main controller, generate substantial distributed information, including (i) information relating to the n pieces of distributed data received by the n units of controllers and (ii) biographical information of the n pieces of distributed data, by using the logical distributed information, and store the substantial distributed information and the n pieces of distributed data received by the n units of controllers in corresponding ones of the n units of storage devices in a second associated manner, wherein the n units of controllers are interposed respectively between the main controller and the n units of storage devices in a one-to-one correspondence with the n units of storage devices, with the n units of controllers being physically separate from the n units of storage devices, and wherein the n units of controllers transmit the substantial distributed information and the n pieces of distributed data received by the n units of controllers to the corresponding ones of the n units of storage devices in the second associated manner, whereby the main controller can only indirectly receive the n pieces of distributed data via each of the n units of controllers and cannot directly acquire the n pieces of distributed data from the n units of storage devices.
2 . The secret sharing storage system according to claim 1 , wherein the main controller acquires the n pieces of distributed data stored respectively in the n units of storage devices in response to a restore indication from the user terminal, restores the original data from the n pieces of distributed data, and sends the original data to the user terminal.
3 . The secret sharing storage system according to claim 1 , further comprising: a second main controller that is communicably connected to the at least one user terminal, the n units of controllers, the random number generator, and the main controller, wherein the main controller sends the logical distributed information and an authority delegation notification to the second main controller, in a case that a malfunction of the main controller is detected; and wherein the second main controller executes distributed processing and restoration processing of the original data in substitution for the main controller in response to the logical distributed information and the authority delegation notification being received from the main controller.
4 . The secret sharing storage system according to claim 1 , further comprising: a communication management server that is communicably connected to a second random number generator, wherein the communication management server sends a second random number generated by the second random number generator to the n units of controllers and the user terminal; and wherein the main controller receives encrypted original data from the user terminal, the encrypted original data being encrypted by the user terminal by using the second random number, and executes the distributed processing on the encrypted original data by using the random number, generates n pieces of encrypted distributed data, and sends the n pieces of encrypted distributed data to the n units of controllers; and wherein, in a case that the n units of controllers receives the encrypted distributed data from the main controller, the n units of controllers decrypt the encrypted distributed data by using the second random number and store distributed data obtained by decryption in the n units of storage devices corresponding to the n units of controllers.
5 . The secret sharing storage system according to claim 4 , wherein the main controller sends an acquisition demand of the n pieces of distributed data to the n units of controllers in response to a restore indication from the user terminal; wherein the n units of controllers encrypt the n pieces of distributed data stored respectively in the n units of storage devices by using the second random number, generate encrypted distributed data, and send the encrypted distributed data to the main controller in response to the acquisition demand; and wherein the main controller restores the encrypted original data from the encrypted distributed data received from the n units of controllers by using the second random number and sends the encrypted original data to the user terminal.
6 . A secret sharing storage method using a secret sharing storage system including a main controller that is communicably connected to at least one user terminal, n units of storage devices, n units of controllers that correspond respectively to the n units of storage devices and are communicably connected to the main controller, and a random number generator, n being an integer of 2 or more, the secret sharing storage method comprising: acquiring, by the main controller, a random number generated by the random number generator, in a case that original data sent from the user terminal is received; executing, by the main controller, distributed processing on the original data by using the random number to generate n pieces of distributed data; generating, by the main controller, logical distributed information relating to generation of the n pieces of distributed data; transmitting, by the main controller, the n pieces of distributed data and the logical distributed information to the n units of controllers in a first associated manner, each controller of the n units of controllers including a first processor, a first memory, a first recording device, and a first communication circuit; deleting, by the main controller, the random number and the original data after transmitting the n pieces of distributed data and the logical distributed information to the n units of controllers in the first associated manner, receiving, by the n units of controllers via the first communication circuit, the n pieces of distributed data and the logical distributed information from the main controller, the n units of controllers being interposed respectively between the main controller and the n units of storage devices in a one-to-one correspondence with the n units of storage devices, with the n units of controllers being physically separate from the n units of storage devices; generating substantial distributed information, including (i) information relating to the n pieces of distributed data received by the n units of controllers and (ii) biographical information of the n pieces of distributed data, by using the logical distributed information; transmitting, by the n units of controllers, the substantial distributed information and the n pieces of distributed data received by the n units of controllers to corresponding ones of the n units of storage devices in a second associated manner, each storage device of the n units of storage devices including a second processor, a second memory, a second recording device, and a second communication circuit; and receiving and storing, by the n units of storage devices via the second communication circuit and the second recording device, the substantial distributed information and the n pieces of distributed data in the second associated manner, whereby the main controller can only indirectly receive the n pieces of distributed data via each of the n units of controllers and cannot directly acquire the n pieces of distributed data from the n units of storage devices.

Description

TECHNICAL FIELD The present disclosure relates to a secure secret sharing storage system using a cloud service which stores a plurality of pieces of distributed data generated by distributed processing of original data. BACKGROUND ART In the related art, a method using polynomial interpolation as a threshold secret sharing method is well known, but this method requires time for calculation processing. Therefore, a threshold secret sharing method using exclusive OR (so-called XOR processing) is well known as a method for satisfying real-time performance. For example, Patent Document 1 suggests a configuration of a secret sharing device that reduces the data amount of distributed data by using a threshold secret sharing method that uses secure XOR processing in which original data is not guessed from distributed data and that can be easily used since the number of variances and a threshold can be freely set. As a threshold secret sharing method in the related art including Patent Literature 1, for example, there is known a method of using a physical random number originally generated based on a signal such as thermal noise (that is, a random number that is difficult to guess) as a random number to be used for the secret sharing processing so that it is difficult to recover the original data from the distributed data. CITATION LIST Patent Literature Patent Literature 1: JP-A-2014-509753 SUMMARY OF INVENTION Technical Problem However, when such a physical random number is used, since a physical random number generator is expensive, it is not easy to install a physical random number generator to each user who performs secret sharing and thus it is difficult to disseminate the secret sharing technology in substance and socially. The present disclosure is suggested in view of the above circumstances in the related art, and an object thereof is to provide a secret sharing storage system and a secret sharing storage method that suppress cost increase due to the installation of a physical random number generator that generates a physical random number used for secret sharing regardless of the number of users who require secret sharing and that support the realization of secure storage of original data to be concealed. Solution to Problem According to the present disclosure, there is provided a secret sharing storage system including at least one user terminal; n units (n: an integer of 2 or more) of storage devices; and a main controller that is communicably connected to a random number generator, in which the main controller acquires a random number generated by the random number generator in a case of receiving original data sent from the user terminal, generates n pieces of distributed data by executing distributed processing on the original data by using the random number, and stores the n pieces of distributed data respectively in the corresponding n units of storage devices. According to the present disclosure, there is provided a secret sharing storage system including n units (n: an integer of 2 or more) of controllers that are provided to correspond respectively to n units of storage devices; a main controller that is communicably connected to the n units of controllers, at least one user terminal, and a random number generator; and a communication management server that is communicably connected to the n units of controllers, the user terminal, and a second random number generator, in which, in a case that the communication management server receives bibliographic information of original data, the communication management server executes distributed processing on a second random number generated by the second random number generator to generate n pieces of distributed random number data, sends the n pieces of distributed random number data respectively to the corresponding n units of controllers, and also sends the second random number respectively to the user terminal, and in a case that the main controller receives encrypted original data obtained by encrypting the original data by using the second random number from the user terminal, the main controller acquires a random number generated by the random number generator, performs distributed processing on the encrypted original data by using the random number to generate n pieces of encrypted distributed data, and sends the n pieces of encrypted distributed data respectively to the corresponding n units of controllers. According to the present disclosure, there is provided a secret sharing storage method using a secret sharing storage system including a main controller that is communicably connected to at least one user terminal, n unit (n: an integer of 2 or more) of storage devices, and a random number generator. The method includes acquiring a random number generated by the random number generator, in a case that original data sent from the user terminal is received; executing distributed processing on the original data by using the random number to ge