Thanks for the answers. I'll be looking forward to see it hit hackernews.† :)

I've mentioned it elsewhere here, but i'd suggest you also look into https://github.com/habnabit/passacre , since its creators put a LOT of value in getting the crypto parts right and its main creator is very responsive online.

And thanks for answering the footnotes. It is an interesting thought that users can be helped by the wiggling animation of the barcode and its inherent suggestion. (That would be worth a trip report on how you got there.)

† I'd prefer to follow an rss feed, but your blog seems to be 90% marketing and only 10% user-relevant posts with no categories.