Method for unlocking software files locked to a specific storage device

• US 5,628,015 A
• Filed: 10/24/1995
• Issued: 05/06/1997
• Est. Priority Date: 11/13/1992
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Singh, Jitendra K.
• Primary Examiner(s): Kriess, Kevin A.
• Assistant Examiner(s): Chavis, John Q.
• Application Number:
  US08/547,969
• Time in Patent Office: 560 Days
• Field of Search: 395/650, 395/700, 380/4
• US Class Current: 726/32
• CPC Class Codes: G06F 21/1063 Personalisation
• CPC Class Codes: G06F 21/121 Restricting unauthorised execution of programs
• CPC Class Codes: G06F 21/80 in storage media based on magnetic or optical technology, e.g. disks with sectors preventing unauthorised reproduction or copying of disc-type recordable media G11B20/00
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G06F 2221/2135 Metering
• CPC Class Codes: G06F 2221/2137 Time limited access, e.g. to a computer or data

Abstract

The present invention provides a method for unlocking software programs which have been locked to a particular disk by the method described in U.S. Pat. No. 5,327,563. This unlocking method determines if a software program has been moved to a new location since it was originally written to a magnetic disk. In addition this method determines if the program has been executed more than a preset number of times and deciphers the software program if deciphering is authorized.

Claims

1. A computer implemented method to unlock a software program, the software program having a known original sector location and a current sector location on a hard disk having sectors, comprising the steps of:

causing the software program to execute if a verification process determines that all of the following conditions are true;

1. the current sector location of the software program on the hard disk is the same as the known original sector location on the hard disk where the computer retrieves the known original sector location on the hard disk; and

2. the computer determines that the software program has been executed less than a trial count number by retrieving from either a first file or a second randomly-generated and randomly-stored file the number of times the program has been executed and determining that the number of times the program has been executed does not exceed the trial count number; and

3. the computer determines that the current sector location on the hard disk of the first file, is the same location as the sector location on the hard disk at which said first file was originally stored by retrieving from said first file or a third randomly-generated and randomly-stored file the original sector location on the hard disk of the first file and comparing the original sector location on the hard disk to the current sector location on the hard disk.

2. A method as in claim 1 further comprising the steps of:

a) retriving, from a file, a decipher key; and

b) utilizing the decipher key to decipher the software program as the computer retrieves the software program from the hard disk and stores the program in a computer memory while keeping the software program on the hard disk encrypted.

3. A method as in claim 1 wherein the verification process executes the software program only if the current sector location of the software program on the hard disk is the same as the known original sector location on the hard disk where the computer retrieves the known original sector location on the hard disk from a fourth computer file previously stored at an original sector location on the hard disk.