Patent ID: 7051213

Claim:
A storage medium data protecting method of protecting data on a storage medium having a plurality of unit storage areas, comprising: a step of generating a random key, encrypting said random key with a password, and writing said encrypted random key the storage medium; a step of encrypting the data with the generated random key, and writing the encrypted data to the storage medium; a step of reading said encrypted key from the storage medium; a step of decoding said encrypted key with said password; and a step of reading and decoding the data on the storage medium with the decoded key, wherein said random key generating step comprises: a step of generating a different random key for each unit storage area of the plurality of unit storage areas, so that said each unit storage area is assigned a different random key, and said assignment of said different random key to said each unit storage area being based on a particular unit storage area to which the data, once encrypted, is to be stored; a step of encrypting each of the different random keys with said password, and a step of writing each of the encrypted different random keys to the storage medium when initializing the storage medium, wherein said data encrypting step comprises a step of encrypting the data with said different random key data corresponding to its said particular unit storage area to write the data, and wherein said data decoding step comprises a step of decoding the data with said decoded key corresponding to said particular unit storage area where the data have been read.