On the subject of PGP GPG encryption for recreational purposes like in a scavenger hunt or escape...

[G+_Sean Miller]

On the subject of PGP/GPG encryption for recreational purposes like in a scavenger hunt or escape-the-room. Is there any method for doing PGP on paper? Say printing out a Page-size QR code that is then scanned in by a cellphone and then decrypted if you know the key? Revisiting my childhood, I always thought it would be fun to send computer-encrypted messages to a friend via paper.

[G+_Ben Reese]

According to Wikipedia, a Version 40 QR code can handle over 4200 characters. I don't see why you couldn't store a PGP key or encrypted message in a QR code.

 

https://en.m.wikipedia.org/wiki/QR_code

[G+_Sean Miller]

So I would type the text into some encryption (PGP or anything else) software, and it would turn the text into gibberish. Then I copy/paste the gibberish into QR code software which would give me a printable image. The receiver would have to do the same in reverse? Is there any text encryption software good for typing/converting/copy-pasting? What about a desktop app for qr-code? Are there any ways to cut down on steps?

[G+_Sean Miller]

Actually I found a couple of apps that can deal with encrypted text QR. It's pretty cool. However, QR encryption hasn't been standardized yet, so the receiver has to have the exact same app you used to encrypt it. Oh well. It's still cool to play around with. This is something I have been idly investigating for a year now. The day that I actually ask the question, I finally find something along the lines of what I'm looking for. Ben Reese Thanks for the "version 40" bit. It gave me something to search for.

[G+_Ben Reese]

Sweet! The escape room type scenario sounds like a fun use. PGP is probably overkill for that, but it should still be doable.

 

If the thought is for recreational use, maybe have 2 QR codes that together make the message. Maybe one with the message and one with the key. If your message is stored in binary and your key is the same length as your message, it's just a matter of x-or'ing the two together. That's a very common programming function, so it should be easy enough to implement in any language.