Cryptsetup - problem when booting the Jessie machine

[roger.tarani@free.fr]

Hi
I use a Jessie machine since approx oct 2016. 
LVM + cryptsetup (standard options of the Debian installer). 
I've done updates each time it was possible. 
I shut up this machine approx in march-may. When i came to boot in in june, i was stuck with cryptsetup :
My passphrase is not ok for cryptsetup. 
«No key available for this passphrase.
cryptsetup: cryptsetup failed, bad password or options?»

I'm 100% sure of my passphrase. 
I've seen on some forums that a Debian update can sometimes lead to this situation. 

I've done nothing on that disk. 

i just tried to enter my passphrase assuming the keyboard is qwerty instead of azerty I use. Howerver, I'm not sure I coul enter special and accentuated characters.  

Is there a way to make visible the characters of my passphrase when typing it?

Thanks for your help

Regards 
Roger