METHOD AND DEVICE FOR PROTECTING DIGITAL DATA BY DOUBLE RE-ENCRYPTION

摘要

A method and a device capable of protecting digital data reliably. Digital data are doubly re-encrypted by using a fixed key and a variable key. The order of using the encrypting keys is first the variable key and then the fixed key, or first the fixed key and then the variable key. The working examples are exemplified by one using a software, one using a hardware and one using a combination of a software and a hardware. The hardware can use a fixed key which has been developed for digital video. The software performs encryption/decryption in a region other than a kernel portion which cannot be used by the user so as to keep the safety of the program and the key used. Specifically, the encryption/decryption are performed by a filter driver in an I/O manager, a device driver serving as a disk driver/net driver and an RTOS utilizing an HAL. Either or both of two filter drivers on both sides of a file system driver can be used.