Encrypted text matching system, method, and computer readable medium

A method for matching encrypted texts, comprising:

• generating first auxiliary data and second auxiliary data, respectively, which are for verification of matching between a first encrypted text that is obtained by encrypting input data and is registered with a storage device and a second encrypted text that is obtained by encrypting input data to be matched, the verification being performed by using a Hamming distance between plaintexts;
• and
• performing one-way conversion on at least part of the second auxiliary data, performing one-way conversion on intermediate data that is generated based on a difference between the first encrypted text and the second encrypted text and on the first auxiliary data, and determining, by using a result of the one-way conversion performed on the intermediate data as well as using the second auxiliary data that underwent the one-way conversion, whether a Hamming distance between plaintexts is equal to or less than a predetermined certain value, the Hamming distance corresponding to the difference between the first encrypted text and the second encrypted text.

A non-transitory computer readable medium storing a program causing a computer to execute:

• a process which generates first auxiliary data and second auxiliary data, respectively, which are for verification of matching between a first encrypted text that is obtained by encrypting input data and is registered with a storage device and a second encrypted text that is obtained by encrypting input data to be matched, the verification being performed by using a Hamming distance between plaintexts;
• and
• a process which performs one-way conversion on at least part of the second auxiliary data, performs one-way conversion on intermediate data that is generated based on a difference between the first encrypted text and the second encrypted text and on the first auxiliary data, and determines, by using a result of the one-way conversion performed on the intermediate data as well as using the second auxiliary data that underwent the one-way conversion, whether a Hamming distance between plaintexts is equal to or less than a predetermined certain value, the Hamming distance corresponding to the difference between the first encrypted text and the second encrypted text.