Patent ID: 8024580

Claim:
A receiving apparatus which receives encrypted input data on a transmission path obtained by encrypting a part or all of data in accordance with a predetermined rule, outputting the encrypted data, extracting predetermined data from said data, executing a predetermined arithmetic operation to the extracted predetermined data, obtaining arithmetic operation resultant data as a result of said arithmetic operation, inserting said arithmetic operation resultant data to a predetermined position of said encryption output, and transmitting the resultant encryption data to said transmission path, comprising: a first data extracting device to extract first data corresponding to said arithmetic operation resultant data from the encrypted input data received through said transmission path; a first decrypting device to decrypt the extracted first data as transmitter certification data; a second decrypting device to decrypt all or part of the received encrypted input data on the basis of a predetermined rule device and to output decrypted input data; a second data extracting device to extract second data from the predetermined position of the outputted decrypted input data; an arithmetic operating device to execute the same arithmetic operation as said arithmetic operation to the data which corresponds to said predetermined data on the second data and output receiver certification data; a comparing device to compare the transmitter certification data with the receiver certification data; and a switching device to switch the output of the receiver apparatus between the decrypted input data and the output of another output generator in accordance with a comparison result of said comparing device.