| 摘要 |
The owner of proprietor interest is in a better position to control access to the encrypted content in the medium if the encryption-decryption key is stored in the medium itself and substantially inaccessible to external devices. Only those host devices with the proper credentials are able to access the key. An access policy may be stored which grants different permissions (e.g. to different authorized entities) for accessing data stored in the medium. A system incorporating a combination of the two above features is particularly advantageous. On the one hand, the content owner or proprietor has the ability to control access to the content by using keys that are substantially inaccessible to external devices and at the same time has the ability to grant different permissions for accessing content in the medium. Thus, even where external devices gain access, their access may still be subject to the different permissions set by the content owner or proprietor recorded in the storage medium. When implemented in a flash memory, the above features result in a particularly useful medium for content protection. Many storage devices are not aware of file systems while many computer host devices read and write data in the form of files. The host device provides a key reference or ID, while the storage device generates a key value in response which is associated with the key ID, which is used as the handle through which the memory retains complete and exclusive control over the generation and use of the key value for cryptographic processes, while the host retains control of files.
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