Data maintenance system, data maintenance method, computer readable medium, and data verification apparatus

A data maintenance method comprising:

• retrieving original data saved in a data source, processing the retrieved original data, and registering obtained processed data;
• during registration of the processed data, computing a digest value of the retrieved original data and a digest value of the processed data, generating reference combined data based on the computed digest values, and computing a digest value of the reference combined data as a reference digest value;
• computing a digest value of the registered processed data as a provisional digest value during verification of the processed data;
• and
• retrieving the digest value that is saved in the data source as the digest value of the original data as a provisional digest value, generating verification combined data based on the provisional digest value of the original data and the provisional digest value of the processed data, computing a digest value of the verification combined data as a verification digest value, comparing the verification digest value with the reference digest value, and determining whether the registered processed data is data derived from the original data in the data source.

A non-transitory computer readable medium recorded with a data maintenance program that causes a computer to execute:

• a data process of retrieving original data saved in a data source, processing the retrieved original data, and registering obtained processed data;
• a reference digest value computation process of, during registration of the processed data, computing a digest value of the retrieved original data and a digest value of the processed data, generating reference combined data based on the computed digest values, and computing a digest value of the reference combined data as a reference digest value;
• a provisional digest value computation process of computing a digest value of the registered processed data as a provisional digest value during verification of the processed data;
• and
• a data verification process of retrieving the digest value that is saved in the data source as the digest value of the original data as a provisional digest value, generating verification combined data based on the provisional digest value of the original data and the provisional digest value of the processed data, computing a digest value of the verification combined data as a verification digest value, comparing the verification digest value with the reference digest value, and determining whether the registered processed data is data derived from the original data in the data source.

A data verification apparatus to verify processed data, the processed data being obtained by processing original data saved in a data source and being registered,

• the data verification apparatus comprising:
• processing circuitry
• to, during registration of the processed data, compute a digest value of retrieved original data and a digest value of the processed data, to generate reference combined data based on the computed digest values, and to compute a digest value of the generated reference combined data as a reference digest value,
• to compute a digest value of the registered processed data as a provisional digest value during verification of the processed data, and
• to retrieve the digest value that is saved in the data source as the digest value of the original data as a provisional digest value, to generate verification combined data based on the provisional digest value of the original data and the provisional digest value of the processed data, to compute a digest value of the generated verification combined data as a verification digest value, to compare the computed verification digest value with the reference digest value, and to determine whether the registered processed data is data derived from the original data in the data source.