The recommended protocol for authentication is Diffie Hellman(DHX) or Diffie Hellman 2(DHX2). They provide a secure way to transport clear-text passwords of up to 64 characters to the server for further processing.
Other authentication modes like Cleartext, Random Number Exchange, and the Two-Way Random Key Exchange protocol support only 8-character passwords. With these modes, any attempt to log in fails if the eDirectory password is longer than 8 characters.