Importance

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Abstract

A method and apparatus for detecting unauthorized copies of software. Each copy of software is uniquely identified by a license number. Each use of each copy is termed a session. Each copy's sessions are numbered sequentially. Each session is assigned a random session stamp when it begins. For each copy, a stamp history is kept, giving the next session number and the session stamps for prior sessions. If software copies having the same license number are used on two different computers, their stamp histories will show different next-session numbers and/or different session stamps for prior sessions, indicating two copies of the software exist, which may be, e.g., a license violation. Each software copy maintains a stamp history database (SHD) comprising a stamp history for itself and for other copies of software for which it has received a stamp history. When a software copy creates data files or transmits information over a network, it attaches all or part of its SHD to the files or information, in order to relay stamp history data to other copies of software. When another software copy receives the data files or information, it updates its own SHD using the attached SHD information. In addition to protection of a software copy, the present method can be applied to protection of a data set, detecting old versions of software that remain in use after newer versions have been installed, and to limit the number of times a copy of software is executed.

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First Claim