Secure computing device, secure computing method, and program

A secure computing device comprising:

• a processor;
• and
• a storage medium having computer program instructions stored thereon, wherein the computer program instructions, when executed by the processor, perform processing of:
• executing secure computing on encrypted data obtained by encrypting plaintext represented in a prescribed expression format for stochastic computing in a homomorphic encryption scheme,
• wherein the secure computing includes a process of acquiring a sum and a process of acquiring a product, and
• wherein the computer program instructions perform processing of:
• determining a value of each digit of a bit string representing the sum as one of a value of a corresponding digit of a bit string that represents first encrypted data and is represented in the expression format and a value of a corresponding digit of a bit string that represents second encrypted data and is represented in the expression format in the process of acquiring the sum that is a sum of the first encrypted data of the encrypted data and the second encrypted data of the encrypted data;
• and
• acquiring a value of each digit of a bit string representing the product using a logical operation according to the expression format in the process of acquiring the product that is a product of the first encrypted data of the encrypted data and the second encrypted data of the encrypted data, the logical operation being a two-input logical operation in which a value of a corresponding digit of the bit string that represents the first encrypted data and is represented in the expression format and a value of a corresponding digit of the bit string that represents the second encrypted data and is represented in the expression format are input.