| 摘要 |
A digital signal recorder for recording a digital signal on a recording medium, including: an input circuit which receives a transmitted digital signal encrypted for protecting said transmitted digital signal using a first encryption method; a decrypting circuit which decrypts said transmitted digital signal into an original data; a key generation circuit which performs a prescribed arithmetic operation to generate a key; an encrypting circuit which receives said key and said original data, and encrypts said original data with said key using a second encryption method; a recording circuit which records, onto said recording medium, a key information which is used for decrypting said encrypted digital signal together with said encrypted digital signal, and a timing control circuit which controls decrypting timing of said decrypting circuit and encryption timing of said encrypting circuit; wherein said key generation circuit has a function for updating said key in connection with recording units of said recording media.
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