Abstract: A signature generating device includes a receiving unit that receives a sequence of data; a summary data generating unit that generates summary data of the data upon reception of each of the data by the receiving unit; an obtaining unit that obtains, when the number of data included in a sequence of the generated summary data reaches a given number, the sequence of the summary data as a block; a setting unit that sets, as a signature subject, a current block constituted by the sequence of the summary data, and the summary data selected from at least one block contiguous to the current block; a digital signature generating unit that generates a digital signature concerning data summarized for the current block; and a sending unit that sends the generated digital signature, the signature subject associated with the digital signature, and the data summarized for the current block.

Abstract: When input data (f0) is read into a digital signature generating apparatus, a hash value (h0) is calculated. The hash value (h0) is stored to a storage area (M1), which has the highest priority rank among 5 storage areas. Subsequently, when input data (f1) is read in, a hash value (h1) is calculated. Since the storage area (M1) is already occupied by the hash value (h0), the hash value (h0) is read out from storage area (M1), emptying the storage area (M1). The read hash value (h0) and the hash value (h1) are concatenated, forming a concatenated hash value (h0|h1) and a hash value (h0,1) is calculated. The hash value (h0,1) is stored to a storage area (M2), which has the highest priority rank after the storage area (M1). When input data (f2) is read in, a hash value (h2) is calculated and stored to the storage area (M1).

Abstract: An image managing method includes dividing the original moving image into a header and a body and generating the group hash value of the header portion, generating the hash value of each item of still image data, connecting the group hash value of the header portion and the hash value of each item of still image data to generate connected hash values, generating a group of the connected hash values as a hash value list, generating the hash value of a Huffman table on the basis of cutting out one still image, and signing to generate signature information of the original moving image, using the group hash value of the header portion, the hash value of the Huffman table, and the hash list as verification data of the original moving image, by adding a digital signature of a video recording terminal to it.

Abstract: A signature generating device includes a receiving unit that receives a sequence of data; a summary data generating unit that generates summary data of the data upon reception of each of the data by the receiving unit; an obtaining unit that obtains, when the number of data included in a sequence of the generated summary data reaches a given number, the sequence of the summary data as a block; a setting unit that sets, as a signature subject, a current block constituted by the sequence of the summary data, and the summary data selected from at least one block contiguous to the current block; a digital signature generating unit that generates a digital signature concerning data summarized for the current block; and a sending unit that sends the generated digital signature, the signature subject associated with the digital signature, and the data summarized for the current block.

Abstract: A print image generating program is capable of printing information that discourages fraudulent distribution of printed documents, irrespective of the type of printer. A print image generating apparatus has an application, a printer driver, a print management unit, and a virtual driver, and is designed to add tracking information that discourages distribution of printed documents when print data is printed. The print management unit monitors print requests from the application. When detecting a print request which was output from the application to the printer driver, the print management unit acquires and interrupts the print request destined for the printer driver. When the virtual driver receives a command from the print management unit, it acquires print data and tracking information, and generates tracking print image data by adding the tracking information to the print data, and gives the generated data to the printer driver.