Secure system for activating personal computer software at remote locations

1. A method of controlling the use of a program file, comprising the steps of:

providing a program file including a loader segment and a registration shell portion to a remote computer having a display, said program file containing a first executive control program representing a limited version of said program file;

entering license transaction information in said registration shell portion;

transmitting said license transaction information from said registration shell to a separate registration program provided in a registration computer, said registration program merging license transaction data with a second executive control program representing a complete version of said program file to generate a unique overlay file;

transmitting said unique overlay file from said registration program to said registration shell, said overlay file containing said second executive control program; and

installing said overlay file in said main program file, thereby allowing complete operation of said program file only when said license transaction information is included in said overlay file.

2. The method in accordance with claim 1 further comprising the step of validating said license transaction information prior to transmitting said overlay file from said registration computer to said remote computer.

3. The method in accordance with claim 2, wherein said validating step insures that said license transaction information is provided by means of a legitimate registration shell.

4. The method in accordance with claim 1 further comprising the step of creating an overlay file which is tamperproof.

5. The method in accordance with claim 4, wherein said tamperproof overlay file is created by encrypting said tamperproof overlay file with an encryption key, providing a cyclic redundancy check value within said encrypted tamperproof overlay file and providing a decryption key to said tamperproof overlay file, said encryption and decryption keys being uniquely determined by the unique contents of the overlay file.

6. The method in accordance with claim 5, wherein a new cyclic redundancy check value is computed each time said overlay is loaded for execution and compared to the cyclic redundancy check value transmitted within said tamperproof overlay file to determine whether said overlay file has been modified since it was originally generated.

7. The method in accordance with claim 1, wherein said license transaction information and said overlay file are transmitted between said registration shell and said registration program through an electronic data link.

8. The method in accordance with claim 1, wherein said license transaction information and said overlay file are entered and installed on a single computer.

9. A system for upgrading a limited program file to a fully operational program file for a period of time comprising;

at least one remote computer, initially provided with a first limited program file containing an overlay loader segment containing a first executive control program representing a limited version of said program file, said overlay loader segment only enabling activation of the fully operational program file when a unique overlay file is presently installed, said remote computer provided with a registration shell program, said registration shell program enabling a user to enter license transaction information, said remote computer provided with an operating system;

a registration computer provided with a registration program, a means for receiving and processing said license transaction information, a means for creating said unique overlay file containing a second executive control program representing a complete version of said program file and at least a portion of said license transaction information, and a means for transmitting said overlay file to said remote computer; and

means provided with said at least one remote computer for receiving said unique overlay file transmitted by said registration computer, for substituting said unique overlay file for said first limited program file and for allowing complete operation of said fully operational program file in said operating system only when said license transaction information is included in said unique overlay file.

10. The system for upgrading a limited program file to a fully operational program file in accordance with claim 9, further including an electronic data link between said remote computer and said registration computer and file transfer processes provided in both said registration computer and said remote computer.

11. The system for upgrading a limited program file to a fully operational program file in accordance with claim 9, wherein said registration computer is provided with a central data base including all registered users as well as a means for validating said license transaction information.

12. The system for upgrading a limited program file to a fully operational program file in accordance with claim 9, wherein said means for creating an overlay file is provided with an encryption key for producing a tamperproof overlay file with a cyclic redundance check value stored therein, and a decryption key, and further wherein said decryption key is transmitted to said remote computer along with said overlay file, said encryption and decryption keys being uniquely determined by the contents of the file.

13. The system for upgrading a limited program file to a fully operational program file in accordance with claim 12, wherein said remote computer is provided with a means for decrypting said overlay file, calculating a new cyclic redundancy check value each time said overlay file is loaded for execution, and comparing this check value to the redundancy check value transmitted by said registration computer within said overlay file.