摘要:
A communication device is secure against an impersonation attack as well. The communication device secretly communicates, with an external device, target data with use of a key shared with the external device. Without being known to a third party, the communication device generates a key shared with the external device using a scheme of which security is proved. Validity of the external device is determined by authentication with use of a key dependent function that is shared with the external device and is dependent on the shared key. If the external device is determined to be valid, for secretly communicating the target data, verification data for verifying validity of the target data is generated from the target data with use of the key dependent function.
摘要:
At the time of manufacturing a DVD to be provided to a rental agent, a provider device writes an agent-rental expiry along with contents onto the DVD. At the time of renting the DVD to a user, a rental agent device writes a user-expiry onto the DVD. A DVD player acquires a current time from a time source device, and compares the current time with each of a prior time, the agent-rental expiry, and the user-rental expiry. The DVD player plays back the content only when playback conditions are met.
摘要:
There is provided a signature generation apparatus capable of preventing transcript attack on signature data. The signature generation apparatus for generating signature data for message data (i) acquires, according to a predetermined acquisition method, a private key, which is different from a private key used in a previous digital signature operation, from among a plurality of private keys generated using a key generation method of a signature scheme in which the plurality of private keys correspond to a single public key, and (ii) performs, using the acquired private key, a digital signature operation on the message data according to a signature method of the signature scheme to generate the signature data.
摘要:
Processing load on an executing device for conducting playback is high during the playback of contents since the executing device performs verification of the contents validity in parallel with the contents playback, and therefore the executing device has to be equipped with a highly efficient processor. The present invention reduces the processing load involved in the verification by using, for the verification, only a predetermined number of encrypted units selected randomly from multiple encrypted units consisting encrypted contents recorded on the DVD. In addition, the present invention is capable of improving the accuracy of detecting unauthorized contents to some extent by randomly selecting a predetermined number of encrypted units every time the verification is performed.
摘要:
A content distribution system for transferring contents between transmission device and reception device. The transmission device includes: key obtaining unit that obtains, from reception device, public keys and public key identifiers; watermark embedding unit that embeds a different public key identifier, as electronic watermark, into each of contents that are identical in substance; an encryption unit that encrypts contents using public keys to generate encrypted contents; and transmission unit that transmits encrypted contents to reception device. The reception device includes: key storage unit storing public keys, public key identifiers, and a private key that makes a pair with one of the public keys; key transmission unit that transmits public keys and public key identifiers to the transmission device; content receiving unit that receives encrypted contents from transmission device; and decryption unit that obtains a content from the received encrypted contents, using the private key.
摘要:
To provide a content delivery system which enables a ciphertext to be reduced in size when using the ElGamal cipher. A content delivery device performs elliptic curve encryption on a content key, generates an encrypted content key that includes an x coordinate of an elliptic curve point obtained by the elliptic curve encryption, and outputs the encrypted content key. A content reception device receives the encrypted content key, and calculates a y coordinate of the elliptic curve point using the x coordinate included in the encrypted content key. The content reception device then performs elliptic curve decryption using the elliptic curve point and other information included in the encrypted content key, to generate a decrypted content key.
摘要:
A transmission apparatus performs a one-way operation on plaintext to generate a first value and transmits the first value, generates first additional information, performs an invertible operation on the plaintext and first additional information to generate connected information, encrypts the connected information using an encryption algorithm to generate ciphertext, and transmits the ciphertext. A reception apparatus receives the first value and the ciphertext, generates second additional information identical to the first additional information, decrypts the ciphertext using a decryption algorithm, which is an inverse-conversion of the encryption algorithm, to generate decrypted connected information, decrypts the decrypted connected information and the second additional information according to an inverse of the invertible operation to generate decrypted text, performs the one-way operation on the decrypted text to generate a second value, compares the first and second values, and judges that the decrypted text is valid only when the first and second values match.
摘要:
A game system in which game software produced to be used in stationary game machines can be used in portable game machines. The game system includes a stationary game machine, a portable game machine, and a memory card connectable to both the stationary and portable game machines. Image data contained in game software produced for the stationary game machine shows an image in the form of free-form surface. The stationary game machine converts the image data to show the image in the form of a polygon according to processing performance of the portable game machine, and stores the converted image data and a game program executable by the portable game machine onto the memory card. The portable game machine executes the game program stored on the memory card, and generates and displays a display image from the image data stored on the memory card.
摘要:
A data processing device for playing back a digital work reduces the processing load involved in verification by using only a predetermined number of encrypted units selected randomly from multiple encrypted units constituting encrypted contents recorded on a DVD. In addition, the data processing device improves the accuracy of detecting unauthorized contents by randomly selecting a predetermined number of encrypted units every time the verification is performed.
摘要:
A data processing device for playing back a digital work reduces the processing load involved in verification by using only a predetermined number of encrypted units selected randomly from multiple encrypted units constituting encrypted contents recorded on a DVD. In addition, the data processing device improves the accuracy of detecting unauthorized contents by randomly selecting a predetermined number of encrypted units every time the verification is performed.