A data generating apparatus is provided that includes a memory storing a program and a processor configured to execute the program to implement processes of sequentially acquiring n sets of data (where n is an integer greater than or equal to 2) included in a predetermined section of time series data and calculating, based on the acquired data, parameter information satisfying a polynomial of degree (k−1) including k random numbers (where k is an integer greater than or equal to 1 and less than n); generating a signature value by adding a signature to secret information based on a secret sharing protocol, the secret information being calculable by acquiring k sets of the acquired data and the parameter information calculated based on the acquired data; and outputting output data including the signature value and a set of the acquired data and the parameter information calculated based on the acquired data.