5. Summary and conclusion

We mustn't forget that a software application is a complex object produced through an artisanal process, and that it ultimately contains defects. All security techniques (redundancy, defensive programming, rework, etc.) have the effect of increasing complexity, and the only reasonable practice is to control the quality of software application production. This quality control involves :

• definition of a (pre-established) quality reference framework ;

• training in these standards (skills) ;

• systematic application and control (improvement).

The introduction of formal methods is a recent development that has made it possible to identify faults as early as the specification phase, and to guarantee that the code produced respects properties that...