04558176 is referenced by 381 patents and cites 17 patents.

A method and apparatus are provided for inhibiting unauthorized copying, unauthorized usage and automated cracking of proprietary software used in computer systems. The computer systems execute protected programs, which are protected by encapsulation and/or encryption. To provide security against unauthorized copying of software, means are provided that detect and inhibit automated cracking of protected programs. These means will destroy or make inaccessible information in the CPU during conditions when automated cracking could occur. These means will also store interrupt contexts in secret to prevent implementation of automated cracking. Additional features may be provided to allow operation as a general purpose computer system, where protected programs are distributed using public key cryptography and a means is provided to convert from this distribution form to the protected execution form.

Title
Computer systems to inhibit unauthorized copying, unauthorized usage, and automated cracking of protected software
Application Number
6/420562
Publication Number
4558176
Application Date
September 20, 1982
Publication Date
December 10, 1985
Inventor
Mark D Winkel
1518 Gloria, Loveland, 80537
CO, US
Mark G Arnold
1400 Grand Ave., Laramie, 82070
WY, US
IPC
H04K 9/00
View Original Source