Patent ID: 7227956

Claim:
A system for encrypting a first signal having successive parts and transmitting the first signal from a first device to a second device in an encrypted form, the system including a transmitting section disposed in the first device and a receiving section disposed in the second device, the transmitting section comprising: an encryption key generator for receiving each part of the first signal and generating an encryption key from each received part of the first signal; a memory for temporarily storing the encryption key, thereby delaying the encryption key with respect to the first signal; an encryption circuit for encrypting each part of the first signal by use of the delayed encryption key generated from an earlier part of the first signal, thereby generating an encrypted signal having successive parts; and a transmitting circuit for transmitting the encrypted signal to the second device; the receiving section comprising: a receiving circuit for receiving the encrypted signal from the first device; a decryption circuit for decrypting each part of the encrypted signal by use of a delayed decryption key, thereby obtaining a decrypted signal having successive parts; a decryption key generator for generating a decryption key from each part of the decrypted signal; and a memory for temporarily storing the decryption key, thereby delaying the decryption key with respect to the decrypted signal and obtaining the delayed decryption key that will be used to decrypt a subsequent part of the encrypted signal.