When we say "off the grid," we often mean off the power grid.

"Off the grid," however, can also mean off of any interconnected network including the Internet. Back in the day before the World Wide Web, many people communicated using what was called FidoNet . You set up a home computer with a dialup modem and the FidoNet software. The FidoNet software 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 acoustic 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 becoming one of these popular methods.
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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 on deaddrops.com or 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 from the reference section of the library--at a library that has a large reference section such as a university library or the main branch of the public library. As long as everyone in the group with whom you wish to communicate the location of your flash drive knows which book to use, you can use a book cipher to encrypt the coordinates of your dead drop.

Let's say you wanted to encrypt the coordinates 39.7682, -86.158. 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 (including spaces) to find the letter (no need to encrypt the spaces between words):

24 5 = t
110 9 = h
40 8 = r
154 10 = e
64 10 = e

If you don’t 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 that you have chosen a location and a method of communicating the coordinates, you’ll need to decide on a container for your USB flash drive. Form follows function and the USB flash drive that I want to use is a micro-SD to USB adapter with a 1GB micro-SD card. It might be more convenient to use since it might be impractical to lug a laptop to the site and instead bring a smart phone. Simply swap out the smart phone’s micro-SD card with the USB dead drop’s micro-SD card and copy files to and from the smart phone’s memory to the USB dead drop’s micro-SD card.

Once the files have been transferred, don’t forget to remove the USB dead drop micro-SD and replace it with the smart phone’s original micro-SD. Reinsert the USB dead drop’s micro-SD into the adapter, put it back in its container, and leave it for the next person to use.

The container, then, could be a simple pill bottle.

Or you can go all fancy-schmancy and use the DaVinci Code Cryptex.

I got mine from Dollar General for around $5.00 USD—you probably won’t find them for that price any more. I would have bought several of them at that price, but it was the only one left. I was very lucky to get it since in the packaging it looked like it was broken. It only took the minor fix of screwing the end cap back on to fix it.

If you can't find an inexpensive DaVinci Code Cryptex you can use a boring old pill bottle or get creative with your container. Nonetheless, if you’re into steampunk the DaVinci Code Cryptex can be used as a hardware lock for your personal USB flash drive.

For geocachers, you may elect not to use a traditional log book and instead make a text file on the flash drive where people can log their visits.