Some documentation about how to go about decoding and inputting a document should be done.... I still haven't figured out how to do this after spending some time first trying to get it build (didn't build on debian stable, needed a debian testing chroot).
Now I can get the base64-strings from the qr-codes, but it's not clear how to pass this to paperback to decode the main document.
At the moment you need to do the following (and the recovery procedure is a bit cumbersome -- there will be a GUI at some point for all of this since ultimately the project is intended for regular people):
% paperback backup [- or the file to back up] -n [threshold] -k [number of shards to make]
The command will print out the contents of the main document QR codes since at the moment the program can't scan the QR codes in the PDFs so you need to manually input the data. Note that the QR codes don't contain Base64 since that is not an efficient way of encoding binary data using QR codes. The QR code data is all encoded in Base10 (but the recovery code can handle any base data because I use multibase[1] prefixes).
And then to recover:
% paperback recover --interactive [- or the path to output the data to]
And it will ask you for the main document data (just copy-paste it, putting an extra newline after each segment) and then the shard data (you can copy-paste the "text fallback" segments from the QR codes) and shard codewords -- also with a newline after each section section. The prompts tell you what to input
"paperback expand" (create new shards from existing ones) works the same way (and also requires --interactive).
I plan to add support for just taking the PDF file and scanning the data from it directly but it seems a bit complicated to do at the moment, and I'm presenting a talk on this project next month at Linux.conf.au so I'm working on that talk right now.