Abstract: 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.

Abstract: A situation recognizing apparatus has a situation change detecting unit, being provided with situation information, configured to detect a situation change on the basis of the situation information, a first storage which stores the detected situation change, an input unit which is provided with a user operation, and a second storage which combines the user operation provided to the input unit with the situation change stored in the first storage and stores the combined user operation and the situation change as a unique pattern.

Abstract: According to one embodiment, a data transmission control section ends transmission of a title without copyright protection at time t2. When transmission time of the title exceeds prescribed time, interruption of the transmission is posted to a reception-side device, and a key discard/creation section creates a new encryption key. A copyright-protected title is transmitted to the reception-side device by using the new key.

Abstract: 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.

Abstract: 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.

Abstract: With each embodiment of the present invention, a content providing system comprises a content encrypting section which encrypts content by use of a session key and a header generating section which encrypts the session key by use of an encryption key in such a manner that the session key can be obtained by use of a decryption key assigned to a user system and generates header information including the encrypted session key and one or more values based on user identification information of each of the user systems that are permitted to obtain the session key. The content providing system transmits the encrypted content and the header information to each user system. Since the header information does not explicitly include user identification information of the user systems, information about whose decryption keys have been revoked is not leaked out in the block box tracing.

Abstract: 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.

Abstract: A transmitting apparatus transmits, to a receiving apparatus, a content that contains at least, in the stated order, a first portion that is encrypted with a shared key shared between the transmitting apparatus and the receiving apparatus, a second portion that is not encrypted, and a third portion that is encrypted with the shared key. In this situation, in the case where the encrypted third portion has become a transmission target after the second portion has been transmitted, and also, there is a possibility that the shared key stored in the receiving apparatus may be invalidated when the encrypted third portion is received, the transmitting apparatus sequentially transmits a fourth portion and the encrypted third portion to the receiving apparatus, the fourth portion containing at least element data that belongs to the last group in the second portion.

Abstract: With each embodiment of the present invention, a content providing system comprises a content encrypting section which encrypts content by use of a session key and a header generating section which encrypts the session key by use of an encryption key in such a manner that the session key can be obtained by use of a decryption key assigned to a user system and generates header information including the encrypted session key and one or more values based on user identification information of each of the user systems that are permitted to obtain the session key. The content providing system transmits the encrypted content and the header information to each user system. Since the header information does not explicitly include user identification information of the user systems, information about whose decryption keys have been revoked is not leaked out in the block box tracing.

Abstract: An information-processing device includes a first interface configured to transmit content to a first communication unit through a network, a second interface configured to receive a first unique identification allocated to the first communication unit from a second communication unit and transmit a second unique identification allocated to the information-processing device to the second communication unit, an identification list configured to store at least one unique identification through the second interface and an identification judgment unit configured to determine whether the first unique identification received through the first interface is stored in the identification list, wherein when the identification judgment unit determines that the unique identification of the first communication unit is stored in the identification list, the first interface allows the content to be transmitted to the first communication unit.

Abstract: A content playback apparatus includes an SKF selecting unit that selects one segment key file from plural segment key files recorded in a DVD media at a time of playback of a content of the sequence key section, a data selecting unit that selects each content corresponding to a segment number of each key entry registered in the selected segment key file, a moving picture data decrypting unit that decrypts the selected moving picture data by a segment key corresponding to the segment number, and a decoder that plays back the decrypted moving picture data.

Abstract: 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.

Abstract: An information-processing device for communicating with a communication device includes a RTT measurement unit configured to measure a round trip time between the information-processing device and the communication device, a RTT judgment unit configured to determine whether the round trip time exceeds a predetermined upper limit value, a unit-type information acquiring unit configured to acquire an identification of the communication device when the round trip time is not greater than the upper limit value, a limit value judgment unit configured to measure amount of cumulative information accumulated during content is transmitted to the communication device, a cumulative information storage unit configured to store the measured amount of cumulative information, and a cumulative information management unit configured to control to store the cumulative information in the cumulative information storage unit when the amount of cumulative information exceeds a given limit value.

Abstract: An aspect of the present invention provides an information communication device for transmitting electronic data encrypted for the purpose of copyright protection, the device includes that an identification information managing unit configured to hold device identification information in connection with other information communication devices acquired through a network, an ID registration processing unit configured to register the device identification information of another connection device when the other communication device satisfies a predetermined distance condition or when common identification information that is held by both information communication devices is received from a portable device, and an authentication and key exchange processing unit configured to, for the purpose of copyright protection, complete authentication and key exchange process (AKE process) only when another information communication device whose device identification information is registered in the identification information

Abstract: A transmitting apparatus includes a transaction transmitting unit configured to transmit to a receiving apparatus a content to be moved to the receiving apparatus, by using a first transaction established with the receiving apparatus, a counter unit configured to count a progress quantity representing a degree of progress of the transmission of the content from a given point of time with respect to the transmission of the content corresponding to the first transaction to obtain a count value, and a transaction switching unit configured to switch the first transaction used for the transmission of the content to a second transaction, if the count value of the counter unit reaches a predetermined value and the transmission of the content is not completed.

Abstract: A content playback apparatus includes an SKF selecting unit that selects one segment key file from plural segment key files recorded in a DVD media at a time of playback of a content of the sequence key section, a data selecting unit that selects each content corresponding to a segment number of each key entry registered in the selected segment key file, a moving picture data decrypting unit that decrypts the selected moving picture data by a segment key corresponding to the segment number, and a decoder that plays back the decrypted moving picture data.

Abstract: A content distribution system encrypts a content by using different session keys assigned to user systems, encrypts each of the session keys with a public key corresponding to a decryption key unique to each user system, generates, for a group of user identification information items, header information including the encrypted session keys, and a first vector which corresponds to a session key of the session keys and is assigned to arbitrary user identification information u in the group, the first vector being set such that an inner product of the first vector and a second vector concerning the user identification information u becomes equal to zjuv (where zj is a constant value of a session key sj assigned to the user identification information u, and v is group identification information to the group), and transmits the header information and one of the encrypted contents to the user systems.

Abstract: A set of users is divided into subsets, and a decipher key is generated for each subgroup by using different key generation polynomials. A session key, that is, a decipher key for ciphered data is distributed so as to be deciphered with the decipher key of each user. Decipher keys of an arbitrary number of users can be revoked. On confiscating a pirate deciphering unit, the black-box tracing is performed by assuming users subject to revocation to be suspects. The tracer assumes the suspects, and investigates the suspects n times (n being the total number of users), so that all pirates in a coalition can be identified.

Abstract: A set of users is divided into subsets, and a decipher key is generated for each subgroup by using different key generation polynomials. A session key, that is, a decipher key for ciphered data is distributed so as to be deciphered with the decipher key of each user. Decipher keys of an arbitrary number of users can be revoked. On confiscating a pirate deciphering unit, the black-box tracing is performed by assuming users subject to revocation to be suspects. The tracer assumes the suspects, and investigates the suspects n times (n being the total number of users), so that all pirates in a coalition can be identified.

Abstract: According to one embodiment, since key information is written after a drive unit and host unit are assembled into a player, it is not necessary to manage, in the assembled player, the correspondence in secret key information between the drive unit and host unit. Further, in the player, even if, for example, the drive unit must be exchanged for another, encrypted key data can be shared simply by writing another key data item.