Patent ID: 7124434
Filing Date: 2006-10-17
Classification: H04L

Abstract:
1. An information transmission system comprising: an information sending apparatus for sending encryption-resultant main information; an information receiving apparatus for receiving the encryption-resultant main information from the information sending apparatus; first means for, before the information sending apparatus sends the encryption-resultant main information to the information receiving apparatus, performing transmission of specified information between the information sending apparatus and the information receiving apparatus to enable the information sending apparatus and the information receiving apparatus to hold in common an encryption key used to encrypt original main information and decrypt the encryption-resultant main information; second means for generating a first random number; third means in the information receiving apparatus for sending the first random number generated by the second means toward the information sending apparatus; fourth means in the information sending apparatus for generating a sync signal in response to the first random number sent from the information receiving apparatus; fifth means in the information sending apparatus for generating key information relating to the encryption key; sixth means for adding the key information generated by the fifth means to a position immediately following the sync signal generated by the fourth means to generate a set of the sync signal and the key information, wherein the sync signal indicates a position of the key information; seventh means for generating a second random number; eighth means for embedding the set of the sync signal and the key information which is generated by the sixth means in the second random number generated by the seventh means to generate a composite signal; ninth means in the information sending apparatus for sending the composite signal generated by the eighth means toward the information receiving apparatus; tenth means for generating the encryption key in response to the key information generated by the fifth means; eleventh means for encrypting the original main information in response to the encryption key generated by the tenth means to generate the encryption-resultant main information; twelfth means in the information sending apparatus for sending the encryption-resultant main information generated by the eleventh means toward the information receiving apparatus; thirteenth means in the information receiving apparatus for detecting the sync signal in the composite signal sent from the information sending apparatus; fourteenth means in the information receiving apparatus for extracting the key information from the composite signal in response to the sync signal detected by the thirteenth means; fifteenth means in the information receiving apparatus for generating the encryption key in response to the key information extracted by the fourteenth means; and sixteenth means in the information receiving apparatus for decrypting the encryption-resultant main information sent from the information sending apparatus in response to the encryption key generated by the fifteenth means.