Note that the 'plaintext password' value is encoded in ISO-10646
UTF-8. It is up to the server how to interpret the password and
validate it against the password database. However, if the client
reads the password in some other encoding (e.g., ISO 8859-1 - ISO
Latin1), it MUST convert the password to ISO-10646 UTF-8 before
transmitting, and the server MUST convert the password to the
encoding used on that system for passwords.