I think just a string of hexadecimal character should be accepted:
Code:
$ cat Fr_password.txt
limité à
$ cat Fr_password.txt | hexdump -C
00000000 6c 69 6d 69 74 c3 a9 20 c3 a0 0a |limit.. ...|
Code:
6c - l
69 - i
6d - m
69 - i
74 - t
c3 a9 - é
20 - space
c3 a0 - à
0a - newline
So in this case, ignoring the newline, the following should be accepted as password:
0x6c696d6974c3a920c3a0