| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To independently control read right and write right to a file with a simple constitution. <P>SOLUTION: Client devices 20<SB>1</SB>, 20<SB>2</SB>do not hold common key cipher-type common key data F<SB>crypt</SB>, and manage only a public key cipher-type public key data F<SB>pub</SB>or a pair of keys F<SB>pub</SB>, F<SB>pri</SB>), to a file server device storing the encrypted file, a digital signature and the authentication data for writing F<SB>write</SB>. In read processing, the client device derives the common key data F<SB>crypt</SB>from the public key data F<SB>pub</SB>by unidirectional function f, decrypts the encrypted file on the basis of the common key data F<SB>crypt</SB>, and verifies the digital signature on the basis of the public key data F<SB>pub</SB>. In write processing, the client device derives the authentication data for write F<SB>write</SB>from the secret key data F<SB>pri</SB>by unidirectional function f, transmits the authentication data for write F<SB>write</SB>to the server device to receive the authentication of write right, and stores the encrypted file and the digital signature. <P>COPYRIGHT: (C)2003,JPO</p> |
