Abstract: A message receiving apparatus for receiving messages from a message transmitting apparatus generates first data for producing a display which urges a user of the message transmitting apparatus to input a message, and generates second data within the first data for specifying a conversion type for secret communication of the message. The message receiving apparatus sends the first data including the second data to the message transmitting apparatus and subsequently receives the message from the message transmitting apparatus. The message transmitting apparatus for transmitting messages to the message receiving apparatus receives the first data for producing the display and the accompanying second data for specifying the conversion type and produces the display according to the first data.

Abstract: A verifier and a claimant notify each other of verifier type information and claimant type information, respectively. The verifier determines a verifier method corresponding to a combination of the verifier type information and the notified claimant type information, generates challenge data in accordance with the determined verifier method, and transmits the challenge data to the claimant. On receiving the challenge data from the verifier, the claimant determines a claimant method corresponding to the combination of the claimant type information and the notified verifier type information. The claimant then performs claimant processing on the challenge data using the determined claimant method to obtain response data, and transmits the response data to the verifier. On receiving the response data from the claimant, the verifier performs verifier processing on the response data using the determined verifier method.

Abstract: In the first devices, MPU 53 generates random number R1 as challenge data. Random number R3 is generated by first encryption IC 54, and then combined with random number R1, encrypted, and sent to second device 52 as encrypted text C1. When encrypted text C2 is similarly received from second device 52, first encryption IC 54 decrypts C2 and separates the decrypted result into first separated data RR2 and second separated data RR4. The first encryption IC 54 returns the first separated data to second device 52 as response data. MPU 53 compares the first separated data returned from second device 52 with random number R1, and in the event of a match, authenticates second device 52 as a legitimate device. The first encryption IC 54 generates the time-varying data transfer key by combining second separated data RR4 with random number R3, and transfers the digital copyrighted data to second device 52 by using the data transfer key.

Abstract: A data transmitting device capable of performing copyright protection processing, when digital data retrieved from the information recording medium is AV data, which includes: an interface section for receiving information specifying the digital data to be output and the data receiving device and for outputting the digital data via the digital interface; a judgment section for judging whether or not the digital data includes video information; an authentication section for authenticating whether not the data receiving device is a proper data receiving device having a function of converting digital data into video data based on authentication data output from the data receiving device; a data retrieval section for retrieving the specified digital data from an external medium; and a control section for controlling the interface section to output the digital data via the digital interface only when the judgment section judges that the digital data includes video information and the authentication section authent

Abstract: A supplier device 70 which supplies title data is equipped with a encryption module 74 for performing an encryption which is substitutive in nature and the user device 90 which uses the title data is equipped with a decryption module 93 for performing a decryption which corresponds to the encryption. The supplier device 70 uses this encryption module 74 to prove its own authorization and authenticate other devices. Similarly, the user device 90 uses this decryption module 93 to prove its own authorization and authenticate other devices.