Multimedia network system

Claim 2

A multimedia network system for transmitting real-time communication type information such as a television video signal and storage type information such as a computer file using at least one transmission path, comprising: a receiving terminal comprising secret-key decryption means for decrypting the real-time communication type information by a secret-key system in which only transmitting and receiving terminals of the information have encryption and decryption keys, public-key decryption means for decrypting the storage type information by a public-key system in which all the terminals commonly have their own encryption keys, and only a receiving terminal of the information has its own decryption key, and second secret-key control means for causing said secret-key decryption means to change a common decryption key in each communication.

Claim 3

A multimedia network system for transmitting real-time communication type information such as a television video signal and storage type information such as a computer file using at least one transmission path, comprising: a transmitting terminal comprising secret-key encryption means for encrypting the real-time communication type information by a secret-key system in which only transmitting and receiving terminals of the information have encryption and decryption keys, public key encryption means for encrypting the storage type information by a public-key system in which all the terminals commonly have their own encryption keys, and only a receiving terminal of the information has its own decryption key, and first secret-key control means for causing said secret-key encryption means to change a common encryption key in each communication, and causing said public key encryption means to encrypt and transmit the changed key; and a receiving terminal comprising a secret-key decryption means for decrypting the real-time communication type information by secret-key system in which only transmitting and receiving terminals of the information have encryption and decryption keys, public-key decryption means for decrypting the storage type information by a public-key system in which all the terminals commonly have their own encryption keys, and only a receiving terminal of the information has its own decryption key, and second secret-key control means for causing said secret-key decryption means to change a common decryption key in each communication.

Claim 4

The system according to claim 3, wherein said transmitting terminal for performing encryption using the secret-key by said secret-key encryption means or said receiving terminal for performing decryption using the secret-key by said secret-key decryption means further comprises time measurement means for measuring an encryption or decryption time, and charge means for calculating charge information in accordance with a transmission or reception time of information measured by said time measurement means.

Claim 5

The system according to claim 3, wherein a file for ordering information from said receiving terminal to said transmitting terminal, and the real-time communication type information transmitted from said transmitting terminal to said receiving terminal in accordance with the file are encrypted using the secret-key by said secret-key encryption means, and a reception confirmation file for the real-time communication type information, which file is transmitted from said receiving terminal to said transmitting terminal, and a charge demand file from said transmitting terminal to said receiving terminal are encrypted by said public key encryption means, and are decrypted by the decryption key inherent to said receiving terminal.

Claim 6

The system according to claim 5, wherein said public-key encryption means of said transmitting terminal encrypts real-time communication type information by logically EX-ORing a real-time communication type information string and a pseudo random number string generated based on the stored data encryption key, and transmits the encrypted real-time communication type information.

Claim 7

The system according to claim 5, wherein said public-key encryption means of said receiving terminal decrypts real-time communication type information by logically EX-ORing a received real-time communication type information string and a pseudo random number string generated based on the stored data encryption key.

Claim 8

The system according to claim 5, wherein said transmitting terminal further comprises digital signature means for putting a digital signature for certifying a transmission source simultaneously with encryption when files are transmitted, and said receiving terminal further comprises confirmation means for confirming the digital signature.