PaperBack: Backing up on… paper?

If you’re holding off on buying a new hard drive until prices return to their pre-flood norms (which may be a while, as we discussed in another article), here’s a novel idea. If you have a ream of A4 paper and a high resolution printer, an open source Windows application lets you store up to 500KB – half a megabyte! – per side of paper.

Called PaperBack, the app is basically a way of turning any file on your computer into a giant bitmap of data matrices – square barcodes that look similar to QR codes, but without the three “targets” around the edge. Each data matrix stores around 80 bytes of data, and with a 200 DPI printer you can squeeze 2400 matrices onto an A4 page, for a total of around 200 kilobytes. Pump the DPI to 600 and the storage capacity of a double-sided sheet of paper jumps to 1 megabyte.

PaperBack was created as a joke by Oleh Yuschuk, but rest assured that it actually works. To test it, I took a screenshot of our website and used PaperBack to print out an encoded version at 200 DPI. You can see the result above. I then dusted off an old USB scanner, plugged it in, hit the Scan button in PaperBack… and voila! The screenshot was restored to its former glory.

To counter some obvious issues with paper-based storage, such as coffee cup rings, PaperBack also includes error correction by way of redundant data blocks. By default, 1 in 5 data matrices is redundant – meaning, in theory, you could restore the original file even if 20 per cent of the paper has been destroyed. There is also built-in compression that’s optimised for text files, which can cram up to 3 megabytes of data onto a single side of paper.

By now you are probably nodding, smiling, quite possibly both, but doubtless at the same time you’re desperately trying to answer a rather valid question: So what’s the point? It may surprise you to learn that there are actually a few valid applications for PaperBack.

Long-term storage, for example: Other than tapes and sapphire hard disks, there are surprisingly few storage mediums that can stand the test of time – and then, the bigger problem is whether you’ll have the hardware to read that data in 50 or 100 years. Acid-free paper with decent ink can last a hundred years without special storage requirements, and can be hand-decoded by a human if for some reason post-apocalyptic Earth lacks digital scanners.

Because of its minimal storage capacity, though, paper-based storage is likely to have just one sensible use: Storing encryption keys. You have probably experienced a CD or USB stick that has become unreadable – and if that happens to be your private encryption keychain, you’re in trouble. If you have a copy of your private key backed up using PaperBack, however – and stored in a safe, perhaps – then you have nothing (except house fires, floods, and other acts of God) to worry about.