[Vince]

This might be besides the point, but limiting a password in any way, be it max length or allowed characters insinuates that you are storing it in plain text, or that you're otherwise using a very insecure storage method. Which is, of course, bad. A hashing method doesn't care about its input and it will always output a fixed length string.

If this is to be used for anything in-game (e.g. a password protected door or something) then I've said nothing.