×

Method and system for preventing unauthorized use of software

  • US 5,113,518 A
  • Filed: 06/03/1988
  • Issued: 05/12/1992
  • Est. Priority Date: 06/03/1988
  • Status: Expired due to Term
First Claim
Patent Images

1. A system for reducing unauthorized use by data processing apparatus of a software program having, as a portion thereof, predetermined values of selected inherent, system independent characteristics of authorized data processing apparatus, said system comprising:

  • means for determining actual values of said selected characteristics for operating data processing apparatus attempting to run said software program;

    means, response to said means for determining, for comparing said determined actual values with said predetermined values;

    means, responsive to said means for comparing, for selectively running said software program;

    wherein said data processing apparatus includes a read only memory (ROM), and said predetermined values include an identification value for said ROM, and said identification value for said ROM comprises a cyclic redundancy check (CRC) value of contents of said ROM; and

    wherein said data processing apparatus includes a processor having at least one register, and wherein said means for determining further comprises;

    means for multiplying a value contained in said register by a first constant (C);

    addressing means for addressing successive locations of said ROM;

    means, responsive to said successive locations, for then successively adding to said register values contained in said successive locations;

    means for then dividing said values contained in said register by a second constant (D) to produce a quotient and a remainder value;

    and means for loading said register with said remainder value, whereby said register then contains said CRC value.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×