| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption conversion apparatus and an encryption conversion method and program capable of preventing the protection strength required by a content owner from being degraded in the case of conversion of encryption systems when organizations share information. SOLUTION: The encryption conversion apparatus 50 carrying out encryption conversion for using a second encryption method to encrypt again data encrypted by a first encryption method includes a conversion means for carrying out the encryption conversion so that the protection strength of the data encrypted by the first encryption method is equal to or more than the protection strength of the data encrypted by the second encryption method. In this case, the conversion means utilizes a computational complexity required for decrypting the encryption to perform the encryption conversion so that the protection strength of the data encrypted by the first encryption method is equal to or more than the protection strength of the data encrypted by the second encryption method. COPYRIGHT: (C)2007,JPO&INPIT
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