Storage medium and method and apparatus for separately protecting data in different areas of the storage medium

• US 7,051,213 B1
• Filed: 11/06/1998
• Issued: 05/23/2006
• Est. Priority Date: 03/18/1998
• Status: Expired due to Term

• Current Assignee: Fujitsu Client Computing Limited (Lenovo Group Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Uchida, Yoshiaki, Kobayashi, Hiroyuki
• Primary Examiner(s): Smithers, Matthew
• Assistant Examiner(s): NGUYEN, MINH DIEU T
• Application Number:
  US09/187,700
• Time in Patent Office: 2,755 Days
• Field of Search: 713/183, 713/168, 713193-194, 380/286, 380/4, 380/21, 380/277, 365/52
• US Class Current: 713/194
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00

Abstract

Disclosed are a method and an apparatus for protecting data on a storage medium by encrypting the data to be recorded on the storage medium with a password. This method comprises a step of, generating, for changing key data on each memory unit by one password, the key data, thereafter encrypting the key data with the password and writing the encrypted data to the storage medium, and a step of encrypting the data with the key data and encrypted data to the storage medium. The method further comprises a step of reading the encrypted key data from the storage medium, a step of decoding the encrypted key data with the password, and a step of decoding the data on the storage medium with the decoded key data. The encryption is done by using the key data generated separately from the password, and it is therefore feasible to prevent the password from being analyzed by decoding a cipher text.

Claims

1. 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.

2. A storage medium data protecting method according to claim 1, wherein said random key generating step comprises a step of generating said random key per logic sector on the storage medium.

3. A storage medium data protecting method according to claim 1, wherein said random key generating step comprises a step of generating different random keys for each writing to said plurality of unit storage areas.

4. A storage medium data protecting method according to claim 1, wherein said random key generating step comprises a step of generating said random keys by combining a predetermined number of pieces of random data.

5. A storage medium data protecting method according to claim 1, further comprising:

a step of decoding, after reading said encrypted key from the storage medium, said encrypted data with an old password designated by a user; and

a step of writing, after encrypting said decoded key with a new password designated by said user, the encrypted data to the storage medium.

6. A storage medium data protecting method according to claim 1, wherein said writing said encrypted random key to the storage medium comprises a step of encrypting said random key with each of a plurality of passwords, and writing said encrypted random keys to the storage medium, and said step of decoding the encrypted key comprises a step of decoding said encrypted key with a designated password.

7. A storage medium data protecting method according to claim 1, wherein said writing encrypted random key to d the storage medium comprises a step of encrypting said random key with a first password, writing the encrypted random key to the storage medium, encrypting said first password with a second password, and writing encrypted first password to the storage medium, and said step of decoding the encrypted key data comprises a step of decoding said encrypted first password with said second password, and obtaining said first password, and a step of decoding said encrypted key with obtained said first password.

8. The storage medium protecting method according to claim 1, said writing said encrypted key is performed for all unit storage areas of the storage medium when initializing the storage medium.

9. The storage medium protecting method according to claim 8, wherein said encrypting the data step comprises:

a step of reading said encrypted key from the storage medium;

a step of decoding the read encrypted key with said password; and

a step of encrypting the data with the decoded key.

10. A storage medium data protecting apparatus for protecting data, comprising:

a storage medium having a plurality of unit storage areas; and

a control circuit for reading and writing the data from and to said storage medium,

wherein said control circuit has;

a write mode of encrypting, after generating a random key, said random key with a password, writing the encrypted key to said storage medium, encrypting the data with the random key, and writing the encrypted data to said storage medium;

a read mode of decoding, after reading said encrypted key from said storage medium, the encrypted key with said password, and decoding the data on said storage medium with the decoded key,

wherein said write mode comprises a mode of generating a different random key for each unit storage area of said plurality of unit storage areas so that said each unit storage area is assigned a different random key, and the 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, encrypting each of the different random keys with said password, writing each of the encrypted keys to said storage medium when initializing the storage medium, and encrypting the data with the random key corresponding to its said particular unit storage area to write the data,

wherein said read mode comprises a mode of decoding the data with the decoded key corresponding to said particular unit storage area where the data have been read.

11. A storage medium data protecting apparatus according to claim 10, wherein said storage medium is constructed of a storage medium from and to which the data is read and written per logic sector, and said control circuit generates said different random key per logic sector on said storage medium.

12. A storage medium data protecting apparatus according to claim 11, wherein said control circuit decodes, after reading said encrypted key from said storage medium, said encrypted key with an old password designated by a user, and writes, after encrypting said decoded key with a new password designated by the user, said encrypted key to said storage medium.

13. A storage medium data protecting apparatus according to claim 10, wherein said control circuit generates different random keys for each writing to said plurality of unit storage areas.

14. A storage medium data protecting apparatus according to claim 10, wherein said control circuit generates said different random keys by combining a predetermined number of pieces of random data.

15. A storage medium data protecting apparatus according to claim 10, wherein said control circuit has:

a write mode of encrypting said random keys with each of a plurality of passwords and writing the encrypted keys to said storage medium; and

a read mode of decoding the read/encrypted key with a designated password.

16. A storage medium data protecting apparatus according to claim 10, wherein said control circuit has:

a write mode of encrypting said key with a first password, writing said encrypted key to said storage medium, encrypting said first password with a second password, and writing the first encrypted password to said storage medium; and

a read mode of decoding said first encrypted password with said second password, obtaining said first password, and thereafter decoding said encrypted key with said first password.

17. An encoding method for protecting data on a storage medium having a plurality of unit storage areas, comprising:

a step of generating different random keys for each unit storage area of the storage medium, encrypting said different random keys with a password, and writing the encrypted keys to the storage medium;

a step of encrypting the data with a different random key corresponding to a particular unit storage area to which the data, once encrypted is to be written, and writing the encrypted data to the storage medium.

18. A decoding method for protecting data on a storage medium having a plurality of unit storage areas, wherein different keys are used for each unit storage area and the different keys are encrypted with at least one password, comprising:

a step of reading the different encrypted keys from the storage medium;

a step of decoding said different encrypted keys with the at least one password; and

a step of decoding the data on the storage medium with a particular decoded key corresponding to a particular unit storage area where the data, once encrypted have been read.

19. A storage medium data protecting method for protecting data on a removable storage medium having a plurality of unit storage areas, comprising:

a step of generating random keys, encrypting said random keys with a password, and writing the encrypted keys to the removable storage medium;

a step of encrypting the data on the removable storage medium with the generated random keys, and writing the encrypted data to the removable storage medium;

a step of reading said encrypted key from the removable storage medium;

a step of decoding said encrypted key with said password; and

a step of decoding and reading the data on the removable storage medium with the decoded encrypted key,

wherein said random key generating step further comprises;

a step of generating different random keys for each a unit storage area of the removable storage medium;

a step of encrypting each of said different random keys for said each unit storage area with said password; and

a step of writing each of the encrypted keys to the removable storage medium,

wherein the data encrypting step comprises a step of encrypting the data on the removable storage medium with a particular random key corresponding to a particular unit storage area to write the data, and

wherein the data decoding step comprises a step of decoding the data on the removable storage medium with said decoded encrypted key corresponding to said plurality of said particular unit storage area where the data, once encrypted, have been read.

20. A storage medium data protecting method of protecting data on a storage medium comprising:

a step of generating a random key, encrypting said random key with a password, and writing said encrypted random key to 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 decoding the data on the storage medium with the decoded key,

wherein said writing encrypted key is performed for all unit storage areas of the storage medium when initializing the storage medium,

and wherein said encrypting the data step comprises;

a step of reading said encrypted key from the storage medium;

a step of decoding the read encrypted key with said password; and

a step of encrypting the data with the decoded key.

21. A storage medium data protecting apparatus for protecting data, comprising:

a storage medium having a plurality of unit storage areas; and

a control circuit for reading and writing the data from and to said storage medium,

wherein said control circuit has;

a write mode of encrypting, after generating a random key, said random key with a password, writing said encrypted random key to the storage medium, encrypting the data with the generated random key, and writing the encrypted data to the storage medium; and

a read mode of decoding, after reading said encrypted key from the storage medium, said encrypted key with said password, and decoding the data on the storage medium with the decoded key, and wherein said write mode has a mode of performing to write encrypted key for all unit storage areas of the storage medium when initializing the storage medium,

and wherein said write mode has a mode of reading said encrypted key from the storage medium, decoding the read encrypted key with said password, and encrypting the data with the decoded key.