| 摘要 |
PROBLEM TO BE SOLVED: To solve problems of a conventional system that a computing unit with a large scale circuit is required, much time is required for the calculations and the authentication time is extended because complicated (sophisticated) calculations are needed for transmission / reception of an encryption key and an authentication method or the like. SOLUTION: A comparator 38 compares an initial vector produced by a receiver and outputted from a converter 37 with an initial vector obtained from a received signal as to whether or not the initial vectors have an identical value, and when the values of the initial vectors are identical to each other, it can be discriminated that the encryption key obtained after that is the same as that of a transmission apparatus. An initial vector outputted from a register 40 is fed to an encryption unit 41 as a first word, encrypted by using an encryption key from an encryption key storage device 39, part of an output of the encryption unit 41 is returned to the register 40 to form a publicly-known OFB mode for a succeeding word, and the output of the encryption unit 41 is fed to an adder 34 as an encryption key to decrypt the encrypted received signal from a synchronization detector 31. COPYRIGHT: (C)2005,JPO&NCIPI
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