The last time SSH was updated in DragonFly, a DragonFly-specific customization, “PasswordAuthentication No”, was reverted to the default.  This meant password logins through SSH worked on DragonFly – which is normal for perhaps every other UNIX-ish operating system, but DragonFly has traditionally defaulted to requiring a key out-of-the-box.

It has been fixed, and you can change the setting back.  This only affected DragonFly-master from August through March.  4.6 users are unaffected.