Thanks Julien for your explanations. It works fine with MD5, with UTF8 to yes or not. No idea why my tests with md5 or not doesn't work yesterday, yet I repeated them several times ? Some confusion and tiredness probably. But now, on the base of your explanation, it's ok :).
nb : I think it would be good to transalte 'clear' by ' mdp en clair' instead of 'Effacer', et 'md5' en 'mdp en md 5' in the frenche translation, it would be more easy to understand.