| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem that an interceptor also decodes data when a decryption key for decoding encryption flows out to the interceptor in the case data distribution is performed only to a predetermined receiver by encryption. <P>SOLUTION: When data distribution is performed between a transmitter 10 and a receiver 30 via relay devices 20a, 20b, different encryption keys are used at each part of a communication path by encrypting the data using different encryption keys respectively to be transmitted by the transmitter 10 and the relay devices 20a, 20b and decoding of the data by the interceptor is avoided unless a necessary decoding key flows out at a part where the interceptor performs interception. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
