Parts needed for your cryptex improvement to your USB Dead Drop:
1 DaVinci Code Cryptex (I got my DaVinci Code cryptex from Dollar General for $5.00 USD, but you could use a homemade cryptex)
1 USB Flash Drive (obviously one small enough in size to fit inside your cryptex--the storage capacity is up to you, but large enough to store the kinds of data you want to share).
When we say "off the grid," we often mean off the power grid. "Off the grid," however, can also mean off of any internconnected network including the Internet. Back in the day before there even was an Internet, many people communicated using what was called FidoNet. You set up a home computer with a dialup modem and the FidoNet software, which was a lot like a modern day discussion forum (back then called "bulletin boards") where you could exchange discussion posts, emails, and even files. You used your computer to dial up the remote computer with your modem, logged in to the FidoNet software and you could check your email, read or post to any discussions you happened to be following, and download or upload data files or software. I liked to download text based role playing games. Lots of people liked to write them and would let you download the games for free. To give you an idea of how long ago this was, one of my first text based role-playing games was one I download using a 300 baud modem with an accoustic coupler!
I don't know if nowadays there are any FidoNet type systems up and running, but if you think about it you still had to be "on the grid," or on the telephone network to use it. These days more and more people are coming up with interesting ways of communicating without being "on the grid;" more and more people are coming up with interesting ways of communicating offline. USB dead drops are becomming one of these popular methods:
Of course, it might be difficult for some people to mount a USB flash drive in a brick wall. I say, set your file sharing free from the brick wall! This way, if you need to, you can move the location of your USB Dead Drop (maybe someone deleted all the data or installed malware on it).
People will then need some method of finding your USB Dead Drop. If you want the location of your USB flash drive to be public, then you can publish the location as a geocache on geocaching.com.
If you want to limit the number of people who have access to your dead drop you can use the public library to communicate the location. Choose an obscure and very boring book that you are confident no one will ever want to read and thus, no one will ever want to check out of the library. As long as everyone in the group with whom you wish to communicat the location of your flash drive knows which book to use, you can use a book cipher (http://en.wikipedia.org/wiki/Book_cipher) to encrypt the coordinates of your dead drop.
Let's say you wanted to encrypt the coordinates 39.7682, -86.158. If you live in indianapolis you can use your GPS to find this location. If you don't live in Indy or don't have a GPS you can use http://maps.google.com/ to find it.
First write the coordinates out in words:
three nine point seven six eight two comma minus eight six point one five eight.
Here's what the first word "three" looks like after it passes through the book cipher:
24 5 110 9 40 8 154 10 64 10
The first number is the page number, the second number is the number of characters to count to find the letter:
24 5 = t
110 9 = h
40 8 = r
154 10 = e
64 10 = e
If you don'y know which book I used then it should be near impossible for you to decipher the message. Thus you could send the coded message by courier, by snail mail, or by ordinary email and even if the message is intercepted, it would be near impossible to decipher the message through cryptanalysis.
On the other hand, if you know which book to use it is simple to decipher the message.
Now you have two methods of communicating the coordinates of your USB dead drop. If you want your flash drive to be accessed by everyone, you can communicate the coordinates by posting it as a geocache on geocaching.com. If you only want a select group of people you've chosen to be able to access your flash drive, you will have to tell that specific group of people which book at the library to use to decipher your book cipher.
Next you have to choose where to place your USB dead drop. It could be as simple as the hollow of a tree where you could just place the naked flash drive. How boring. Or you could choose to put the flash drive in a pill bottle and then put it in the hollow of the tree. Again, how boring.
Get creative with your containers! For example, I placed a geocache in a mole chaser: http://molechasersinternational.com/original.html
The mole chaser uses a 555 timer to make a relay buzz. It seemed to keep the moles out of the yard, but eventually the relay broke, so I took the guts out and put a note pad and pen in it and placed it as a geocache.
Using the DaVinci Code cryptex adds a nice steampunk look to your USB Dead Drop. Read the rest of this instructable to learn how to use it.