I'd recommend against shortening the key length, given that keeping the keys hard to guess is how you're keeping them private. See https://gist.github.com/7224

I'd recommend against shortening the key length, given that keeping the keys hard to guess is how you're keeping them private. See https://gist.github.com/722474 https://gist.github.com/722474 for a proof of concept scraper. If the key length dropped to 4 chars (and you kept l, o, L, and O in the set), there would only be 7,311,616 urls to try to find all the notes.