TECHNICAL FIELD

The present invention relates to a technical field of secret computation that performs data processing while keeping data concealed. For example, the present invention relates to a technique of secret multivariate analysis.

BACKGROUND ART

As a conventional art of secret computation for performing data processing while keeping data concealed, a technique described in Patent literature 1 is known. In the conventional art of secret computation, the following three phases are performed.

1. Encryption phase: to encrypt data to make it concealed.

2. Secret computation phase: to use an algorithm or a protocol capable of target computation for the original data while keeping the encrypted data, that is, cyphertext as is and to process the cyphertext.

3. Decryption phase: to decrypt the cyphertext obtained as a result of processing in the secret computation phase to obtain a target computation result.

PRIOR ART LITERATURE

Patent Literature

Patent literature 1: Japanese Patent Application Laid-Open No. 2017-028617

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The above conventional art performs all of target computation processing in “2. Secret computation phase.”

In general, secret computation algorithms are more complicated in processing than algorithms that compute data without encrypting. For this reason, time necessary for processing computation by secret computation algorithms is longer than time necessary for processing computation by plaintext computation algorithms. Therefore, if all algorithms that use complicated computation such as linear regression that requires solving linear equations and principal component analysis that requires computing eigenvalues and eigenvectors of matrices are processed by secret computation, the time required for the processing may become enormous.

An object of the present invention is to provide a secret computation system and method that can perform secret computation at faster speed than before while keeping data concealed.

Means to Solve the Problems

A secret computation system according to one aspect of the present invention is a secret computation system for performing computation while keeping data concealed, comprising a cyphertext generation device that generates cyphertext by encrypting the data, a secret computation device that generates encrypted basic statistics by performing secret computation of predetermined basic statistics using the cyphertext while keeping the cyphertext concealed, and a computation device that generates decrypted basic statistics by decrypting the encrypted basic statistics and performs predetermined computation using the decrypted basic statistics.

Effects of the Invention

It is possible to perform secret computation at faster speed than before while keeping data concealed.

