04903296 is referenced by 103 patents and cites 6 patents.

Method and apparatus which restricts software, distributed on magnetic media, to use on a single computing machine. The original medium is functionally uncopyable, until it is modified by the execution of a program stored in a tamper proof co-processor which forms a part of the computing machine. The modified software on the original medium may then be copied, but the copy is operable only on the computing machine containing the co-processor that performed the modification.

Title
Implementing a shared higher level of privilege on personal computers for copy protection of software
Application Number
651184
Publication Number
4903296
Application Date
November 12, 1986
Publication Date
February 20, 1990
Inventor
Steve R White
New York
NY, US
Liam D Comerford
Carmel
NY, US
Akhileshwari N Chandra
Mahopac
NY, US
Agent
Jack M Arnold
Assignee
International Business Machines Corporation
NY, US
IPC
H04L 9/00
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