Data management apparatus and data management method

A data management apparatus comprising:

• a storage that stores a distributed ledger in which one or more hash values and one or more time stamp tokens are stored in time series, the one or more hash values respectively being generated from one or more files, the one or more time stamp tokens proving one or more confirmation times;
• and
• a processor that performs a plurality of verification processes for the one or more files and the one or more confirmation times, the plurality of verification processes including first to third verification processes, wherein
• the first verification process is a process of verifying whether or not the one or more files used to generate the one or more hash values have been tampered with,
• the second verification process is a process of verifying whether or not the one or more confirmation times proven by the one or more time stamp tokens have been tampered with, and
• the third verification process is a process of verifying a sequence of the one or more files and the one or more confirmation times, wherein when the processor controls an output device to display verification results for three or more files or confirmation times,
• the processor controls the output device to display a verification result for an oldest file or confirmation time and a verification result for a latest file or confirmation time, and
• the processor controls the output device not to display a verification result for at least one file or confirmation time between the oldest file or confirmation time and the latest file or confirmation time until an operation performed by a user on an input device is received.

A data management method comprising:

• storing, in a distributed ledger by a processor in time series, one or more hash values and one or more time stamp tokens, the one or more hash values respectively being generated from one or more files, the one or more time stamp tokens proving one or more confirmation times;
• and
• performing, by the processor, based on a received user input a plurality of verification processes for the one or more files and the one or more confirmation times, the plurality of verification processes including first to third verification processes, wherein
• the first verification process is a process of verifying whether or not the one or more files used to generate the one or more hash values have been tampered with,
• the second verification process is a process of verifying whether or not the one or more confirmation times proven by the one or more time stamp tokens have been tampered with, and
• the third verification process is a process of verifying a sequence of the one or more files and the one or more confirmation times, wherein
• in response to receiving a first predetermined user operation from an input device, the processor performs the third verification process and does not perform the first verification process and the second verification process.