I would suggest increasing the maximum length from 5. Many applications that don't use iterated hashing schemes like PBKDF2 recommend much longer passphrases for security against brute-force [1].
[1] Off the top of my head: cryptsetup with plain dm-crypt recommends a random English sentence of > 135 characters length (i.e. a passphrase of 27 words at 5 characters per word).
[1] Off the top of my head: cryptsetup with plain dm-crypt recommends a random English sentence of > 135 characters length (i.e. a passphrase of 27 words at 5 characters per word).