| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To eliminate trouble that it is necessary to acquire a title key for decoding for each information block in a service for dividing information contents into information blocks to which serial numbers are given, encrypting and transmitting the information blocks. <P>SOLUTION: An encryption section C of a server side device 1 encrypts a master key M(J) that is original for second and following information blocks, using a master key M(J-1) to which a preceding number is given, and non-encrypted arbitrary M(K), a title key T(J) encrypted by an encryption section B13 using a master key, and an information block C(J) encrypted by an encryption section A12 are transmitted to a client side device 3 via a transmission section 15 and a network 2 (1≤J≤12). A decryption section C35 first uses a release key M(K) to sequentially decrypt master keys after M(K+1), further, the title key T(J) is decrypted by a decryption section B34, and the information block C(J) is decrypted by a decryption section A35, respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
