| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption and decryption method of downloading data in which downloading data can be encrypted and decrypted with high security in a system comprising a continuous data generator, a date reproducer and a key management device while facilitating key management, and to provide a monitoring system employing that method. SOLUTION: In a system comprising a device for generating continuous data and downloading it while encrypting, a device for decrypting and reproducing the downloaded encrypted data, and a key management device holding information about the keys, the downloading device acquires newest key number and corresponding key information from the key management device, encrypts the generated data by using that key information and downloads the encrypted data while adding a key number. When the downloaded encrypted data is decrypted by the decryption device, the key number added to the encrypted data is acquired and transmitted to the key management device in order to acquire corresponding key information and then the encrypted data is decrypted and reproduced by using the key information. COPYRIGHT: (C)2006,JPO&NCIPI
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