Abstract: The media inherent key storing unit 220 prestores an inherent key Ki, the conversion unit 230 generates an encrypted inherent key Ji from the inherent key read from the media inherent key storing unit 220, the random number generating unit 331 generates a random number R1, the encryption unit 252 generates an encrypted random number S1, the decryption unit 333 generates a random number R?1 from the encrypted random number R1, and the mutual authentication control unit 334 compares the random number R?1 with the random number R1 and, if the random number R?1 matches the random number R1, judges that the memory card 200 is an authorized device. If the memory card 200 and the memory card writer have successfully authenticated each other, the memory card writer encrypts a content using a decrypted inherent key. If the memory card 200 and the memory card reader have successfully authenticated each other, the memory card reader decrypts an encrypted content using the decrypted inherent key.

Abstract: A content recording/reproducing system, which records and reproduces a sub-content relating to a main content, includes a distribution device, first and second recording media, a recording device and a reproducing device. The first recording medium that is non-rewritable prestores key data based on which a public key is derivable, and the main content. The distribution device outputs verification information that includes the sub-content and is generated by applying a digital signature to relative information relating to the sub-content based on a secret key corresponding to the public key. The recording device acquires and records the verification information on the second recording medium that is rewritable.

Abstract: A data protection system is provided that reduces, to a degree, the amount of encrypted data that is distributed to a plurality of terminals. In the data protection system a terminal whose decryption keys are exposed by a dishonest party is made to be unable to decrypt the data correctly, while other terminals are able to decrypt the data correctly. The data protection system includes a plurality of terminals, and an encryption device that encrypts distribution data distributed to each terminal. Each terminal is corresponded with one node on a lowest level of a 4-ary tree structure or the like having a plurality of hierarchies.

Abstract: A device that ensures that one device acquires and updates a list used for judging whether the other device in communication is valid or invalid, in a device authentication system. When a list H stored in a personal computer 200 is old, the personal computer 200 acquires a latest version of the list H and a latest version of a list D from outside an internal network, updates the list H stored therein to the latest version, and updates the list D stored therein to the latest version.

Abstract: In an information input/output system, a user device inputs and outputs information to and from external sources including a key management device. The system includes the key management device that securely outputs invalid-device information specifying an invalid device unit that has been made invalid for use, and the user device that includes an input/output unit and a host unit. Via the input/output unit, input and output of information is enabled between the host unit and the external sources. The host unit securely receives, via the input/output unit, the invalid-device information outputted by the key management device and judges whether or not the input/output unit is an invalid device unit by referring to the received invalid-device information. When judging, that the input/output unit is an invalid device, the host unit thereafter prohibits input and output via the input/output unit.

Abstract: Apparatuses are classified into a plurality of categories, and based on a media key and device key data held by apparatuses belonging to the respective categories, revocation data intended for revoking the device key held by a specific apparatus of the respective categories is generated for the respective categories, and recorded on a recording medium.

Abstract: An encryption transmission apparatus and an encryption reception apparatus avoid attack that takes advantage of a re-transmission request. A server apparatus encrypts a content key five times, thereby generating five encrypted content keys, calculates a hash value of the content key, and transmits the five encrypted content keys and the hash value. An image playback apparatus receives the five encrypted content keys and the hash value, decrypts the five encrypted content keys thereby generating five content keys, calculates hash values, each corresponding to the generated content keys, and compares the calculated hash values with the received hash value, respectively. If at least one of the five calculated hash values matches the received hash value, the corresponding content key is considered correct. Conversely, if none of the five calculated hash values matches the received hash value, it is considered a decryption error.

Abstract: An encryption device, a decrypting device, a secret key generation device, a copyright protection system and a cipher communication device including: a CRL memory unit memorizing a CRL, a device key ring memory unit memorizing a specific device key KD_A in every IC card used in a decrypting device, a content key memory unit memorizing a content key Kc, which is a secret key for decrypting content, and a hashing function processing unit calculating a hashing value of the CRL memorized in the CRL memory unit. The devices further including an Ex-OR unit carrying out an exclusive OR between the hashing value and the device key KD_A memorized in the device key ring memory unit, and an Enc unit encrypting the content key Kc memorized in the content key memory unit using an output value of an Ex-OR unit.

Abstract: A data player for reading contents encrypted by a decoding key from a digital medium, and playing the encrypted contents by using the decoding key which is stored in a key storage unit, comprises: a key obtaining unit for performing mutual authentication with the key storage unit to obtain the decoding key stored in the key storage unit; a key holding unit for holding the decoding key; a playback state obtaining unit for monitoring the playback state of the digital medium; and a contents decoding unit for decoding the encrypted contents by using the decoding key. The decoding key is obtained by the key obtaining unit and stored in the key holding unit, and the encrypted contents read from the digital medium is decoded with the decoding key by the contents decoding unit to play the contents. The decoding key stored in the key holding unit is discarded according to the playback state of the digital medium which is obtained by the playback state obtaining unit.

Abstract: A copyright protection system includes a recording device and a reproduction device. The recording device writes encrypted content, an encrypted content key for decrypting the encrypted content, and license information on a recording medium on which a unique media number has been recorded in an unrewritable state. The license information is generated using both the media number and the encrypted content key, and therefore reflects both values. The reproduction device reads the media number, the encrypted content key, and the license information from the recording medium, and judges whether the license information reflects both the media number and the encrypted content key. The reproduction device decrypts the encrypted content key, and decrypts the encrypted content using the content key only if the license information reflects both values. Thus, the copyright protection system allows only original recording media to be reproduced, and prohibits reproduction of copy recording media.

Abstract: An encryption device, a decrypting device, a secret key generation device, a copyright protection system and a cipher communication device including: a CRL memory unit memorizing a CRL, a device key ring memory unit memorizing a specific device key KD_A in every IC card used in a decrypting device, a content key memory unit memorizing a content key Kc, which is a secret key for decrypting content, and a hashing function processing unit calculating a hashing value of the CRL memorized in the CRL memory unit. The devices further including an Ex-OR unit carrying out an exclusive OR between the hashing value and the device key KD_A memorized in the device key ring memory unit, and an Enc unit encrypting the content key Kc memorized in the content key memory unit using an output value of an Ex-OR unit.

Abstract: An apparatus generates first shared information that is shared by the apparatus and a recording medium by performing a first bilateral authentication. The apparatus encrypts overwrite data that is used to erase key information item recorded in the recording medium using the first shared information. Encrypted overwrite data is transferred to the recording medium. Second shared information is generated and shared by the apparatus and the recording medium by performing a second bilateral authentication between them. The apparatus receives data that is encrypted using the second shared information and that has been used by the recording medium for erasing key information. Encrypted data is decrypted using second shared information item and key information recorded in the recording medium is erased when the decrypted data is identical to overwrite data.

Abstract: A deactivation method is for a system including a communication terminal, a secure device, and a management apparatus. An identification number and communication identification code are notified to the management apparatus while the secure device is attached to the communication terminal. The management apparatus holds the identification number and the communication identification code by correlating them, acquires an identification number of a secure device to be deactivated, when instructed to deactivate the secure device by an authentic owner of a right to use the secure device, extracts the communication identification code in accordance with the identification number, and transmits the deactivation authentication code to an apparatus identified by the extracted communication identification code. If the communication terminal receives the deactivation authentication code while the secure device is attached to it, the secure device is deactivated.

Abstract: An encryption apparatus 100a including: a CRL storage unit 111 storing a CRL; a device key ring storage unit 112 storing a device key KD_A specific to each copyright protection module 210a used by a decryption apparatus 200a; a content key storage unit 113 storing a content key Kc that is a secret key for encrypting a content; a hashing function processing unit 114 calculating a hash value of the CRL stored in the CRL storage unit 111 according to a hashing function; and an Ex-OR unit 115 obtaining an exclusive OR value between the hash value and the device key KD_A. The encryption apparatus also includes an Enc unit 116 encrypting the content key Kc using an output value from the Ex-OR unit, and storing the hash value, the encrypted content key and the encrypted content in a DVD2a.

Abstract: Provided is a content distribution system that prevents different keys to be derived between an encryption apparatus and a decryption apparatus. A random-number generating unit 112d, in an encryption apparatus 110d, generates a random number s, and a first function unit 113d generates a functional value G(s) of the random number s, and generates a verification value a and a shared key K from the functional value G(s). An encryption unit 114d generates a first cipher text c1 of the verification value a using a public-key polynomial h, and a second function unit 115d generates a functional value H(a,c1) of the verification value a and the first cipher text c1, and a random-number mask unit 116d generates a second cipher text c2=s xor H(a,c1). A decryption unit 123d, in a decryption apparatus 120d, decrypts the first cipher text c1 using a secret-key polynomial f, to generate a decryption verification value a?.

Abstract: The media inherent key storing unit 220 prestores an inherent key Ki, the conversion unit 230 generates an encrypted inherent key Ji from the inherent key read from the media inherent key storing unit 220, the random number generating unit 331 generates a random number R1, the encryption unit 252 generates an encrypted random number S1, the decryption unit 333 generates a random number R?1 from the encrypted random number R1, and the mutual authentication control unit 334 compares the random number R?1 with the random number R1 and, if the random number R?1 matches the random number R1, judges that the memory card 200 is an authorized device. If the memory card 200 and the memory card writer have successfully authenticated each other, the memory card writer encrypts a content using a decrypted inherent key. If the memory card 200 and the memory card reader have successfully authenticated each other, the memory card reader decrypts an encrypted content using the decrypted inherent key.

Abstract: A system structured from a management device, a content key distribution device and a plurality of terminals suppresses the data volume of a terminal revocation list (TRL). The management device generates and transmits a TRL formed from data that expresses terminal IDs of all terminals to be invalidated, by only a value and a position of a common bit string in the IDs, to the content key distribution device. Each terminal holds a terminal ID that includes a manufacturer ID and a serial number, and requests the distribution of a content key by sending the terminal ID to the content key distribution device. The content key distribution device refers to the TRL, judges whether the terminal ID transmitted from the terminal is that of an invalidated terminal, and if negative, encrypts and transmits the content key to the terminal.

Abstract: 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.

Abstract: A content protection system prevents illegal key acquisition, without checking uniqueness of device keys. The content protection system includes a key data generation apparatus and a user terminal. The key data generation apparatus converts first key data, which is for using content, based on a predetermined conversion rule, thereby generating second key data, encrypts the second key data using a device key held by valid terminals, and outputs the encrypted key data. The user terminal obtains the encrypted key data, decrypts the encrypted key data using a device key held by the user terminal, thereby generating second key data, converts the second key data based on a re-conversion rule corresponding to the conversion rule, thereby generating the first key data, and uses the content with use of the generated first key data.

Abstract: A data converter (1) capable of reducing a size of the total implementation in a device is a processing apparatus that performs secret converting processing predetermined to input data with 64 bits, the data converter including a finite field polynomial cubing unit (10), data integrating units (11a) to (11d), (12) and (13), a first converter (14), a second converter (15), a data splitting unit (16), and a data integrating unit (17). The finite field polynomial cubing unit (10) performs cubing, on the 32 bits data, in the polynomial residue class ring with a value in the finite field GF (28) as a coefficient and respectively outputs data with 32 bits.