Patent ID: 7174464

Claim:
A method of making a user piece of software secure by means of a user processing and memorizing unit containing at least one reconstitution secret, said piece of software operating on a user data processing system, and the method comprising the following steps: (a) in a stage of generating modified data: (1) and in a substage of creating data, using a generation piece of software to establish original data associated with the user piece of software; (2) and in a modification substage, using a generation secret and at least a portion of the associated original data to determine modified data; (b) in a stage of distribution, distributing the user piece of software and the associated modified data to a user; and (c) in a stage of using the user piece of software together with the associated modified data on a user system, and in a substage of reconstituting the original data; (1) for a user possessing a reconstitution unit including a reconstitution secret: (i) subdividing the modified data into at least a first portion and a second portion; (ii) selecting the first portion of the modified data as an input parameter; (iii) transferring the input parameter from the user system to the reconstitution unit; (iv) enabling the reconstitution unit to determine at least one output parameter on the basis of the reconstitution secret and the input parameter; (v) transferring the output parameter from the reconstitution unit to the user system; and (vi) running at least one reconstitution function making use of at least a portion of the output parameter and the second portion of the modified data to obtain the original data; and (2) for a user not possessing the reconstitution unit, allowing the user piece of software to be used at best with the modified data.