Andrew Findlay writes:
(1): The latest LDAP spec introduced pwprep to solve this problem, but hardly anything implements it yet. It will be many years before you can depend on common LDAP clients doing itproperly.
It's not just a client-side issue. Most sites store a password hash in their server rather than the cleartext password. That means the client needs to encode password with the same character encoding and preparation as whatever hashed the server-side password. (E.g. the /etc/passwd program.) Or the server needs to prepare cleartext passwords it receives from the client the same way, but it's likely a bad idea for the server to e.g. assume client passwords are latin-1 and convert to UTF-8.