摘要:
A signature generation apparatus and a signature verification apparatus which can prevent the occurrence of norm zero vector forgery attack. The signature generation apparatus (110) includes a signature generation unit (114) which generates signature data (S) for a message (m) using a private key stored in a private key storage unit (112), and converts the format of the signature data (S) so that the first sub-element of the N sub-elements in the signature data (S) indicates 0 without changing the norm of the signature data (S). The signature verification apparatus (120) includes a signature verification unit (124) which judges whether or not the first sub-element of the N sub-elements included in the signature data (S) indicates 0, and determines the signature data (S) as unauthorized data when judging that it is not 0.
摘要:
A reception apparatus includes a first timer and sends to a distribution apparatus a first date-time clocked by the first timer. The distributing apparatus includes a second timer, and generates expiry information based on a difference obtained by subtracting, from the first date-time, a second date-time that is clocked by the second timer. The expiry information is used to adjust a usage expiry date-time of content. The reception apparatus judges whether playback of the content is permitted based on the first timer and the expiry information. With this arrangement, unauthorized use of the content beyond the expiry date-time is prevented.
摘要:
A program converter (1) converts a program (P) which performs arithmetic addition processing to execute encryption, into a converted program (tP) which performs processing equivalent to the processing of the program (P). The program converter (1) includes: a key data extraction unit (10) which extracts key data from the program (P); an addition table generation unit (11) which generates an addition table from the extracted key data; a conversion table extraction unit (12) which extracts a conversion table from the program (P); a table merger unit (13) which generates a merger table by merging the generated addition table and the extracted conversion table; a random number generation unit (14) which generates a random number; a table randomization unit (15) which generates a randomized merger table by randomizing the merger table using the generated random number; and a converted-program generation unit (16) which generates the converted program (tP) according to the generated randomized merger table.
摘要:
A parameter generation apparatus for generating parameters causing no decryption error for an NTRU cryptosystem so that an encrypted communication can be carried out between an encryption apparatus and a decryption apparatus in a secure and reliable manner. The parameter generation apparatus includes: a provisional parameter generation unit operable to generate a set of provisional parameters that do not cause any decryption errors, based on error condition information that is provided in advance, the error condition information indicating a condition for causing no decryption error; and an output parameter generation unit operable to generate an output parameter that does not cause any decryption errors, using the set of provisional parameters, based on a lattice constant that is calculated from the set of provisional parameters.
摘要:
An encrypted communication system, capable of performing processing with the speed higher than the conventionally achieved speed, includes an encryption device and a decryption device sharing parameters that satisfy p=3 and q=2^k (k: an integer of 2 or greater). The decryption device generates a public key and a private key using the parameters, the encryption device encrypts a plain text using the public key, and then, the decryption device decrypts the encrypted text using its own private key.
摘要:
A program converter (1) converts a program (P) which performs arithmetic addition processing to execute encryption, into a converted program (tP) which performs processing equivalent to the processing of the program (P). The program converter (1) includes: a key data extraction unit (10) which extracts key data from the program (P); an addition table generation unit (11) which generates an addition table from the extracted key data; a conversion table extraction unit (12) which extracts a conversion table from the program (P); a table merger unit (13) which generates a merger table by merging the generated addition table and the extracted conversion table; a random number generation unit (14) which generates a random number; a table randomization unit (15) which generates a randomized merger table by randomizing the merger table using the generated random number; and a converted-program generation unit (16) which generates the converted program (tP) according to the generated randomized merger table.
摘要:
A signature generation apparatus and a signature verification apparatus which can prevent the occurrence of norm zero vector forgery attack. The signature generation apparatus (110) includes a signature generation unit (114) which generates signature data (S) for a message (m) using a private key stored in a private key storage unit (112), and converts the format of the signature data (S) so that the first sub-element of the N sub-elements in the signature data (S) indicates 0 without changing the norm of the signature data (S). The signature verification apparatus (120) includes a signature verification unit (124) which judges whether or not the first sub-element of the N sub-elements included in the signature data (S) indicates 0, and determines the signature data (S) as unauthorized data when judging that it is not 0.
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.