| Patent application number | Description | Published |
|---|
| 20090138714 | COMMUNICATION APPARATUS, KEY SERVER, MANAGEMENT SERVER, COMMUNICATION SERVER, CONTENT DISTRIBUTION SYSTEM, COMMUNICATION METHOD, AND RECORDING MEDIUM - A plurality of first encrypted pieces is generated by encrypting the pieces with a first encryption key. The second encrypted piece is generated by encrypting at least one of the pieces with a second encryption key. The first encryption key and the second encryption key for encrypting the same piece are different from each other. A communication apparatus receives a first encrypted piece or a second encrypted piece from other communication apparatus for each piece, transmits a request message for requesting a decryption key for decrypting the encrypted piece to a key server, and receives the decryption key from the key server in response to the request message. | 05-28-2009 |
| 20090249490 | COMMUNICATION APPARATUS, COMMUNICATION SYSTEM, TRANSMISSION METHOD, AND COMPUTER PROGRAM PRODUCT - A communication apparatus stores encrypted pieces having plural pieces as a part of a content encrypted, and number of transmission times. At least one first piece is encrypted by plural different encryption keys. The communication apparatus selects as priority pieces plural encrypted pieces corresponding to at least one first piece among the first pieces, based on number of untransmitted encrypted pieces of which number of transmission times is zero among plural encrypted pieces of which first piece is encrypted, and stores priority piece information specifying the priority piece. When a piece request is received from other communication apparatus, the communication apparatus determines an encrypted piece to be transmitted, based on priority piece information, and transmits the encrypted piece to the other communication apparatus. | 10-01-2009 |
| 20090282250 | COMMUNICATION APPARATUS, SERVER, AND COMPUTER PROGRAM PRODUCT THEREFOR - A communication apparatus receives, from another communication apparatus, a plurality of encrypted pieces obtained by encrypting a plurality of pieces constituting a part of a content and obtains a part or all of decryption keys used for decrypting the encrypted pieces. The communication apparatus also obtains an invalid piece list showing one or more identifiers of one or more encrypted pieces that can respectively be decrypted by using one or more decryption keys that have already been invalidated. In the case where at least one of the encrypted pieces is listed in the invalid piece list, the communication apparatus deletes the at least one of the encrypted pieces, based on an obtainment status of the encrypted pieces or an obtainment status of the decryption keys. | 11-12-2009 |
| 20090316897 | COMMUNICATION APPARATUS, KEY SERVER, AND DATA - A communication apparatus that encrypts a plurality of pieces that constitute a part of data and transmits the encrypted pieces stores an encrypted piece that is one of the pieces encrypted by another communication apparatus, and first decryption key information used for decrypting the encrypted piece, while keeping the encrypted piece and the first decryption key information in correspondence with each other. Further, the communication apparatus generates temporary information that can be different at each time of generation, further performs an encrypting process on the encrypted piece based on the temporary information, and outputs a new encrypted piece. The communication apparatus transmits the new encrypted piece, the first decryption key information that is stored in correspondence with the encrypted piece, and second decryption key information used for decrypting the encrypting process. | 12-24-2009 |
| 20100008509 | COMMUNICATION APPARATUS, KEY SERVER, AND MANAGEMENT SERVER - A communication apparatus obtains file information indicating all or a part of first and second encrypted pieces obtained by encrypting a plurality of pieces constituting a part of a content and version management information with which it is possible to judge whether the file information has validity and receives, for each of the pieces, one of the first encrypted piece and the second encrypted piece from another communication apparatus, by using the file information. The communication apparatus transmits, to a key server, a request message for requesting decryption keys each being used for decrypting the one of the first encrypted piece and the second encrypted piece received for a different one of the pieces and the version management information of the file information used to obtain the one of the first encrypted piece and the second encrypted piece in correspondence with each of the pieces and receives the decryption keys. | 01-14-2010 |
| 20100054698 | APPARATUS, METHOD, AND COMPUTER PROGRAM PRODUCT FOR RECORDING CONTENT - An apparatus determines whether a combination of a certificate type of a content certificate recorded on a source recording medium and a medium type of the source recording medium is a proper combination. If the combination is a proper combination, the apparatus requests a license server, which is connected to the apparatus via a network, to give approval to record content on a target recording medium. If the apparatus is a legitimate DVD recorder, the license server sends to the content recording apparatus a content certificate including on the source recording medium as the certificate type. The apparatus records the content together with the received content certificate on the target recording medium. | 03-04-2010 |
| 20110131470 | MEMORY CHIP - According to one embodiment, a memory chip, which is connected to a controller that controls reading and writing of data in response to a request from an external device, includes: a memory including a special area that is a predetermined data storage area; a key storage unit that stores therein a second key that corresponds to a first key used by the external device to convert the data; a converting unit that receives, from the controller, data to be written into the special area and generates converted data by converting the data to be written using the second key; and a writing unit that writes the converted data into the special area. | 06-02-2011 |
| 20110246791 | MEMORY CHIP, INFORMATION STORING SYSTEM, AND READING DEVICE - According to one embodiment, a memory chip, which is connected to a writing device that writes data and to a reading device that reads data, includes: a memory including a first area that is a predetermined data storage area; a second encryption key generating unit that receives second key information stored in the reading device and generates a third key; and a sending unit that transmits, to the reading device, second encrypted data obtained by encrypting data stored in the memory using the third key. The second encrypted data is received by the reading device and is decrypted by using a fourth key that is stored in the reading device and that corresponds to the third key. | 10-06-2011 |
