Patent US1097410A successfully refreshed from Google Patents.
Patent US5677952A successfully refreshed from Google Patents.
US5677952A
Expired / Lapsed
US
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Method to protect information on a computer storage device
Assignee: International Business Machines Corp
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Filing: 1994-12-06
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Granted: 1997-10-14
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Expires: 2014-12-06
Abstract
Abstract A method, using a secret key, to protect information in a storage disk of a computer, where the secret key is derived from a password entered into the computer by an authorized user. The method begins by applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length that is a function of the size of a sector of the storage disk. The sector is associated or otherwise identified by the index used by the pseudorandom function to generate the pseudorandom bit string. The pseudorandom bit string is then used to encrypt and decrypt data accesses to and from the sector.
Inventors
- 👤 George R. Blakley, III
- 👤 Phillip W. Rogaway
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:52
CPC Classifications
G; G06; G06F; G06F21/00; G06F21/30; G06F21/31; G06F21/45; G06F21/46; G06F21/60; G06F21/602; G06F21/62; G06F21/70; G06F21/71; G06F21/72; G06F21/78; G06F21/80; G06F21/82; G06F21/85; H; H04; H04L; H04L9/00; H04L9/06; H04L9/065; H04L9/0656; G06F2211/00; G06F2211/007; H04L2209/00; H04L2209/04; H04L2209/046
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
92 words
A method, using a secret key, to protect information in a storage device of a computer, the secret key being derived from a password entered into the computer by an authorized user, comprising the steps of: applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length that is equal to a portion of the storage device associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the portion of the storage device.
Claim 2
Independent Claim
92 words
A method, using a secret key, to protect information in a storage device of a computer, the secret key being derived from a password entered into the computer by an authorized user, comprising the steps of: applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length that is equal to a portion of the storage device associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the portion of the storage device.
Claim 3
Dependent Claim
25 words
The method as described in claim 1 wherein the storage device is a hard disk and the portion is a sector of the hard disk.
Claim 4
Dependent Claim
28 words
The method as described in claim 1 wherein the secret key is stored in a volatile memory of the computer and vanishes under one or more predetermined conditions.
Claim 5
Dependent Claim
51 words
The method as described in claim 3 wherein the predetermined conditions include the authorized user turning off the computer, the authorized user logging off from the computer, the authorized user locking the computer, or expiration of a predetermined time period during which the computer is not used by the authorized user.
Claim 6
Dependent Claim
47 words
The method as described in claim 1 wherein the step of applying the length-increasing pseudorandom function to the secret key includes the step of transforming the secret key into one or more tables of pseudorandom numbers to facilitate generation of the pseudorandom bit string given the index.
Claim 7
Independent Claim
100 words
A method, using a secret key, to protect information in a storage disk Of a computer, the secret key being derived from a password entered into the computer by an authorized user, comprising the steps of: applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage disk associated with the index; combining a data block of the information with the pseudorandom bit string to generate a ciphertext; and storing the ciphertext in the sector to protect the data block against unauthorized disclosure.
Claim 8
Independent Claim
100 words
A method, using a secret key, to protect information in a storage disk Of a computer, the secret key being derived from a password entered into the computer by an authorized user, comprising the steps of: applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage disk associated with the index; combining a data block of the information with the pseudorandom bit string to generate a ciphertext; and storing the ciphertext in the sector to protect the data block against unauthorized disclosure.
Claim 9
Dependent Claim
33 words
The method as described in claim 6 further including the step of using the pseudorandom function to encrypt and decrypt other storage device accesses while the authorized user is logged onto the computer.
Claim 10
Dependent Claim
26 words
The method as described in claim 7 wherein the other storage device accesses are performed by evaluating the pseudorandom function at one or more sector indexes.
Claim 11
Independent Claim
95 words
A method to protect information on a storage device of a computer, comprising the steps of: deriving a secret key from a password entered into the computer by an authorized user; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage device associated with the index; encrypting a data block of the information with the pseudorandom bit string to generate a ciphertext; and storing the ciphertext in the sector to protect the data block against unauthorized disclosure.
Claim 12
Independent Claim
95 words
A method to protect information on a storage device of a computer, comprising the steps of: deriving a secret key from a password entered into the computer by an authorized user; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage device associated with the index; encrypting a data block of the information with the pseudorandom bit string to generate a ciphertext; and storing the ciphertext in the sector to protect the data block against unauthorized disclosure.
Claim 13
Dependent Claim
43 words
The method to protect information as described in claim 9 further including the step of: retrieving the ciphertext stored at the physical location in response to a read request; and decrypting the ciphertext with the pseudorandom bit string to derive the data block.
Claim 14
Dependent Claim
23 words
The method as described in claim 9 wherein the secret key is derived from the password and other information stored in the computer.
Claim 15
Dependent Claim
18 words
The method as described in claim 11 wherein the other information includes a unique identifier for the computer.
Claim 16
Dependent Claim
22 words
The method as described in claim 9 wherein a slow-to-compute function is applied to the password prior to deriving the secret key.
Claim 17
Dependent Claim
59 words
A computer, comprising: a storage device; means for processing a password entered by an authorized user to generate a secret key; means for using the secret key and an index to generate a pseudorandom bit string having a predetermined length; and means for encrypting and decrypting data accesses to and from the storage device using the pseudorandom bit string.
Claim 18
Dependent Claim
59 words
A computer, comprising: a storage device; means for processing a password entered by an authorized user to generate a secret key; means for using the secret key and an index to generate a pseudorandom bit string having a predetermined length; and means for encrypting and decrypting data accesses to and from the storage device using the pseudorandom bit string.
Claim 19
Dependent Claim
44 words
The computer as described in claim 14 wherein the index is a file number identifying a file associated with the location in the storage device, and wherein the predetermined length of the pseudorandom bit string is made equal to the length of the file.
Claim 20
Dependent Claim
29 words
The computer as described in claim 15 further including means for compressing and decompressing the file, such that the file is compressed prior to encryption and decompressed following decryption.
Claim 21
Independent Claim
121 words
A method, using a secret key, to protect information on a computer having a disk, comprising the steps of: deriving a user key from a password entered into the computer from an authorized user; encrypting the secret key with the user key to generate a value that is stored along with information identifying the authorized user; recovering the secret key in response to subsequent entry of the password by the authorized user; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the disk associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the sector.
Claim 22
Independent Claim
121 words
A method, using a secret key, to protect information on a computer having a disk, comprising the steps of: deriving a user key from a password entered into the computer from an authorized user; encrypting the secret key with the user key to generate a value that is stored along with information identifying the authorized user; recovering the secret key in response to subsequent entry of the password by the authorized user; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the disk associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the sector.
Claim 23
Dependent Claim
28 words
The method as described in claim 17 further including the step of replacing the value with a second value associated with a second password of the authorized user.
Claim 24
Independent Claim
133 words
A method, using a secret key shared by a plurality of authorized users, to protect information on a computer having a disk, comprising the steps of: for each authorized user of the computer, deriving a user key from the authorized user's password and encrypting the secret key with the user key to generate a value that is then stored along with an identifier for the user; recovering the secret key in response to subsequent entry of a password from one of the authorized users; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the disk associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the sector.
Claim 25
Independent Claim
133 words
A method, using a secret key shared by a plurality of authorized users, to protect information on a computer having a disk, comprising the steps of: for each authorized user of the computer, deriving a user key from the authorized user's password and encrypting the secret key with the user key to generate a value that is then stored along with an identifier for the user; recovering the secret key in response to subsequent entry of a password from one of the authorized users; applying a length-increasing pseudorandom function to the secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the disk associated with the index; and using the pseudorandom bit string to encrypt and decrypt data accesses to and from the sector.
Claim 26
Dependent Claim
97 words
An article of manufacture, comprising: a computer-readable storage medium having a substrate; and computer program data encoded in the substrate of the computer-readable storage medium, wherein the computer program data comprises: means for applying a length-increasing pseudorandom function to a secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage disk associated with the index; and means for using the pseudorandom bit string to encrypt data accesses to the sector of the storage disk and to decrypt data accesses from the sector of the storage disk.
Claim 27
Dependent Claim
97 words
An article of manufacture, comprising: a computer-readable storage medium having a substrate; and computer program data encoded in the substrate of the computer-readable storage medium, wherein the computer program data comprises: means for applying a length-increasing pseudorandom function to a secret key and an index to generate a pseudorandom bit string having a length equal to a sector of the storage disk associated with the index; and means for using the pseudorandom bit string to encrypt data accesses to the sector of the storage disk and to decrypt data accesses from the sector of the storage disk.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-10-13 | 2001-04-14 | 2001-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-10-13 | 2005-04-14 | 2005-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-10-13 | 2009-04-14 | 2009-10-14 | $7700.00 | Window Closed / Lapsed |