Introduction: How to Use the DaVinci Code Cryptex (Steampunk USB Drive Hardware Encryption): a Fun Improvement to Your USB Dead Drop (or Geocache)

In this instructable I will show you how to use a DaVinci Code cryptex. It can be used as a ready-made beautiful Steampunk-like hardware encryption for your USB drive and/or a fun container to impove your USB Dead Drop ("anonymous, offline, peer-to-peer file sharing network in public space using a USB device"). I'll show you how to rotate the dials of the cryptex and line up the letters of the combination to unlock the cryptex. I'll show you how to open the cryptex and insert your USB flash drive. Finally I'll show you how to close and lock the USB flash drive inside the cryptex.

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

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 ( 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 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 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:

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.

Step 1: A Combination Lock

The DaVinci cryptex is a combination lock much like a bicycle combination lock. For this demonstration I've set the combination to "green."

Step 2: Line Up the Letters

Rotate the dials until all the letters in the word "green" line up between the two arrows on the case of the cryptex.

Step 3: Open the Cryptex

Once the password letters ("green") are lined up between the two arrows on the case of the cryptex, pull the cryptex open.

Step 4: The USB Flash Drive

This is the USB flash Drive I used for this demonstration. It is the kind that folds up and you can attach it to your keychain.

Step 5: Put the Flash Drive in the Cryptex

Insert your flash drive into the internal barrel of the cryptex.

Step 6: Close the Cryptex

Close the cryptex.

Finally, spin all the dials to mix up the combination.

Here's a video that demonstrates the complete procedure for opening and closing the cryptex:

Congratulations! You learned how to use a DaVinci Code cryptex. You learned how to rotate the dials of the cryptex and line up the letters of the combination to unlock the cryptex. You Learned how to open the cryptex and insert your USB flash drive. Finally You learned how to close and lock the USB flash drive inside the cryptex. The cryptex is a fun improvement to your USB dead drop.


SparkySolar (author)2014-11-01

When I made lots of mulah in my past,I bought 2 differet sizes.

The big Cryptex came in a rosewood inlaid box,

Treknology (author)2012-08-02

Libraries, these days, are on top of their catalog of books and rarely keep anything "dull and boring". I suggest you choose something that CANNOT be checked out of the library, such as something from the Reference shelves.

KRA5H (author)Treknology2012-08-03

That might be a good idea. The security of this kind of "public key" encryption relies on being unable to figure out which book was used for the cipher key. It should be ok to select such a book long as the particular section of books that can't be checked out of the library contains hundreds of books to choose from. This will, of course, weaken somewhat the security of the cipher since the set of books to choose from is much smaller.

Treknology (author)KRA5H2012-08-04

The complete set of Encyclopaedia Brittanica, the full version of the Oxford English Dictionary?

KRA5H (author)Treknology2012-08-09

I checked the Nora Branch of the Indianapolis Public Library and it has a very small reference section. It would be easy to conduct a brute force attack to figure out which book was used for the public key--it might only take a few hours to go through all the books to find the correct book.

Maybe the Main Library has a larger reference collection.

A University library might be an even better choice since these libraries often have large collections of books that cannot be checked out.

RabidAlien (author)KRA5H2012-10-08

Heh. See if you can sneak into the "Restricted" section. I'd suggest after bedtime, when Filch is asleep.

Shonenrek (author)2012-08-14

Another great use for a Cryptex is for a really sweet USB holder. As long as only you know the combo, you can use it to keep your flash drive safe from anyone who may wish to access it. Of course, encryption is also a good idea.

KRA5H (author)Shonenrek2012-08-16

I had a previous instructable about using the davinci code cryptex as a steampunk carrying case for your usb drive. it obviously doubles as hardware encryption for said drive.

I deleted it because it wasn't a featured instructable. I like to keep my featured versus not featured average at or above 50%.

vincent7520 (author)2012-08-02

Same idea as a combination lock.
The great improvement is that with this very clever device they will stole both the USB key AND the Criptex. -LOL-

KRA5H (author)vincent75202012-08-02

Any USB dead drop is subject to vandalism or theft. If your USB dead drop is cemented into a brick wall and someone accidenlty or intentionally breaks the connector off, the USB is useless. Then you have to chip it out of the wall, replace it, and re-mortar it.

This improvement makes your USB dead drop easy to replace if stolen. It is also easy to move to another location, and easy to notify your peer-to-peer file sharing network of the new coordinates.

vincent7520 (author)KRA5H2012-08-02

You are certainly right.

But then again it may well be the whole thing didn't improve your sense of humor !

Gilius (author)2012-08-02

Where can you buy a cryptex?

KRA5H (author)Gilius2012-08-02

If you can't find the Dollar General DaVinci Code cryptex for $5.00 you can make one:

tinpusher (author)KRA5H2012-08-02

I have a Cryptex that I won during the Google "Davinci Code Challenge" back in 2006 before the movie came out. Sadly, though, I did not win the grand prize. I did, obviously since I received the cryptex with url for final puzzles, make it into the finals. It was great fun.

tjk1939 (author)2012-08-02

I found the Cryptex pictured on Amazon for $59.95, you got a steal for the $5.00 stated.

KRA5H (author)tjk19392012-08-02

If you can't find the Dollar General DaVinci Code cryptex for $5.00 you can make one:

Istarian (author)2012-07-31

Nice project, and that's a cool thing there. :)


I think how hard the code is to break depends both on the means of encryption and the message itself.

Any straight substitution cipher using words would need to carry a message short enough not to contain too many commonly used letters. Using e, for instance, too much means that which code stands for e is more easily guessed if the basic cipher is known.

Security through obscurity helps, but once we know it's a book cipher, if it exceeds a certain length and doesn't hide the words (i.e. the sequences are words and each word is a separate sequence) then vowels can probably be found and if the words contain enough vowels then the human brain might be able to come up with them.

If I suspected that you were hiding a gps location and I knew it was an ordinary book cipher of the sort you suggest, I suspect it could probably be cracked even without the book.

phase90 (author)Istarian2012-08-02

I don't see how the vowels could be found. Using his example of the the word "T H R E E," the numbers are 154 10 and 64 10. It is just coincidence that the second number is 10. Depending on the book, it could be 15, 21, or even 237. It doesn't even have to be the first instance of the letter on that page. Because you are not limited to reusing a number pair for each letter, there are more that 26 combinations for the alphabet. I would think it would be hard to find a pattern if it is applied right.

Now if the coder gets lazy and starts reusing pairs for letters because he doesn't want to find a new one, all bets are off.

vikingboy (author)Istarian2012-08-02

I am sorry but you are wrong, it is exactly for the reason you describe, i.e. that the frequency of certain letters etc can reveal the message in a straight substitution cypher, that a public key type cypher was developed.
In a book code as described there is absolutely no relationship between the encrypted message as sent and the original message. How are you going to work out what a message is, ie. 12,34,56,766,234,234. when firstly you dont know what type of cypher it is and then even if you know it is some type of book code you cant resolve that "12" represents as the 12th page,or word,or chapter of any particular book even less what particular letter, it could be anything.

This code type is so effective that it was used and I believe continues to be used by both sides during the cold war , number sequences were simply transmitted in the open over radio , and received by the spies wherever they are operating. Without knowing the "book" it is virtually indecipherable..

actimm (author)2012-08-02

Yes, the book cipher you describe is very similar to the "Playfair Cipher" described in Arthur C Clarke's Venus Prime series. He also spells out, no pun intended, how to use it and another cipher as well.

As for the dead drop idea, I would be more inclined to try to come up with a way to lock it to something to keep people from walking off with it.

planetroverrobo (author)2012-07-31

Hey I have the same flashdrive

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