Patent ID: 7363448

Claim:
A data storage apparatus including a storage unit having a storage area, the data storage apparatus comprising: read key registration means for registering a first read key that is transmitted from a first information processing apparatus and that permits reading data from the storage area; write control means for controlling writing data in the storage unit so that writing new data in the storage area is prohibited until data stored in the storage area is read for the first time; and read control means for controlling reading data from the storage unit so that reading data from the storage area is permitted if a second read key that is transmitted from the first information processing apparatus or a second information processing apparatus matches the first read key when reading data from the storage area is requested by the first information processing apparatus or the second information processing apparatus, wherein the write control means controls writing data in the storage unit so as to further write a digital signature in the storage area, the digital signature being generated by encrypting data to be written in the storage area and being transmitted together with the data to be written in the storage area, and wherein, when checking the data stored in the storage area is requested without the second key being transmitted from the first information processing apparatus or the second information processing apparatus, the read control means controls reading data from the storage unit so as to read the digital signature from the storage area and to transmit the digital signature to the first information processing apparatus or the second information processing apparatus.