1 - Process to protect, using at least one blank unit ( 60 ) including at least memorization means ( 15 ) and processing means ( 16 ), a vulnerable software ( 2 v ) against its unauthorized usage, said vulnerable software ( 2 v ) being produced from a source ( 2 vs ) and working on a data processing system ( 3 ), said protection process comprising: defining: a set of dependent functions, whose dependent functions are liable to be executed in a unit ( 6 ), a set of triggering commands for said set of dependent functions, said triggering commands being liable to be executed in the data processing system ( 3 ) and to trigger the execution in a unit ( 6 ), of the dependent functions, for each triggering command, an order corresponding at least in part to the information transmitted from the data processing system ( 3 ) to a unit ( 6 ), so as to trigger the execution of the corresponding dependent function in a unit ( 6 ), said order having the form of at least one argument of the triggering command, a method of renaming of the orders enabling to rename the orders so as to obtain triggering commands with renamed orders, and restoring means ( 20 ) designed to be implemented in a unit ( 6 ) during a usage phase (U), and enabling to restore the dependent function to execute, from the renamed order, constructing exploitation means enabling to transform the blank unit ( 60 ) into a unit ( 6 ) able to implement the restoring means ( 20 ), creating a protected software ( 2 p ): by choosing, at least one algorithmic processing which, during the execution of the vulnerable software ( 2 v ), uses at least one operand and enables to obtain at least one result, by choosing at least one portion of the source of the vulnerable software ( 2 vs ) containing at least one chosen algorithmic processing, by producing a source of the protected software ( 2 ps ) from the source of the vulnerable software ( 2 vs ), by modifying at least one chosen portion of the source of the vulnerable software ( 2 vs ) to obtain at least one modified portion of the source of the protected software ( 2 ps ), this modification being such that: during the execution of the protected software ( 2 p ) a first execution part ( 2 pes ) is executed in the data processing system ( 3 ) and a second execution part ( 2 peu ) is executed in a unit ( 6 ), obtained from the blank unit ( 60 ) after upload of information, the second execution part ( 2 peu ) executes at least the functionality of at least one chosen algorithmic processing, at least one chosen algorithmic processing is split so that during the execution of the protected software ( 2 p ), said algorithmic processing is executed, by means of the second execution part ( 2 peu ), using dependent functions, for at least one chosen algorithmic processing, triggering commands with renamed orders are integrated to the source of the protected software ( 2 ps ), so that during the execution of the protected software ( 2 p ), each triggering command with renamed order is executed by the first execution part ( 2 pes ) and triggers in the unit ( 6 ), the restoring, by means of the restoring means ( 20 ), of the order and the execution, by means of the second execution part ( 2 peu ), of the corresponding dependent function, and a sequence of the triggering commands with renamed orders is chosen among the set of sequences allowing the execution of the protected software ( 2 p ), and by producing: a first object part ( 2 pos ) of the protected software ( 2 p ), from the source of the protected software ( 2 ps ), said first object part ( 2 pos ) being such that during the execution of the protected software ( 2 p ), appears a first execution part ( 2 pes ) which is executed in the data processing system ( 3 ) and whose at least a portion takes into account that the triggering commands with renamed orders are executed according to the chosen sequence, and a second object part ( 2 pou ) of the protected software ( 2 p ), containing the exploitation means, said second object part ( 2 pou ) being such that, after upload to the blank unit ( 60 ) and during the execution of the protected software ( 2 p ), appears the second execution part ( 2 peu ) by means of which the orders are restored and the dependent functions are executed, and uploading the second object part ( 2 pou ) to the blank unit ( 60 ), with the intention of obtaining the unit ( 6 ), and during a usage phase (U) during which the protected software ( 2 p ) is executed: in the presence of the unit ( 6 ) and each time a triggering command with renamed order, contained in a portion of the first execution part ( 2 pes ) imposes it, restoring in the unit ( 6 ), the identity of the corresponding dependent function and executing it, so that said portion is executed correctly and that, consequently, the protected software ( 2 p ) is completely functional, and in the absence of the unit ( 6 ), in spite of the request by a portion of the first execution part ( 2 pes ) to trigger the execution of a dependent function in the unit ( 6 ), not being able to fulfill said request correctly, so that at least said portion is not executed correctly and that, consequently, the protected software ( 2 p ) is not completely functional.