This feature should be not very hard to implement.
With a few enhancements the cobinatorics of the passphrase go through the roof.
- Include more languages. Maybe let the user import word lists for their language. Maybe I speak English, French and Spanish. So my passphrase could use words for all three languages.
- Use more than one word separator. It would be nice to give a list of characters which are suitable for the user to use as a word seperator. And the generator could randomly use one of them between each word.
- Give an option for typos. Maybe one can choose how many words should include typos. Meaning one or more words will be chosen an a character will be switched with a random character/symbol (or randomly chosen from a user defined set).
So the passphrase generator could be customized such that instead of just giving
boxcar_april_shoplift_gothic
it could give
boxcar*avril Ladendiebstahl_go&hic
- english word
- star as separator
- french word
- space as separator
- german word
- underscore as seperator
- english word with typo
So EVEN if I knew you used 2 english words and 1 french and 1 german word the complexity would be rather high