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Mystery Cache

Solving Puzzles III - Codes & Ciphers (Basic)

A cache by Bob & Brenda - Reno Send Message to Owner Message this owner
Hidden : 5/26/2013
2.5 out of 5
2 out of 5

Size: Size: micro (micro)

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Geocache Description:

Cache is not located at the posted coordinates.

Congratulations to Doctor A for the FTF

This is the third in a series of caches that we hope will help cachers learn some of the tricks to solving puzzle caches. Although experienced puzzle solvers can jump in at any point in the series, each successive lesson is meant to build on concepts that were demonstrated in the previous caches. The first cache in the series contains some background information on puzzle caches as well as a link to the tools we use when solving puzzle caches.

This series is not meant to be an "end all" on how to solve every puzzle cache that exists. It is only a starting point on what to look for when you see a puzzle cache. If you go through this series, you should be able to solve most puzzle caches that have a difficult of 3 stars or less. If we gave away all our secrets, then we wouldn't have anything to do but put out lamp post caches.

This series of caches contains the following caches

Cache Techniques
GC4AFC5 Hidden Information
GC4AJ0W Lists
GC4ANJW Codes & Ciphers (Basic)
GC4ANKB Codes & Ciphers (Advanced)
GC4AZHP Images & Steganography
GC4AZHW Wordplay
GC4B2YM Mathematics
GC4B2YP Logic
GC4B2ZK Final Exam


Alert: There are downloadable files in our toolbox and printable copies (PDF) of the puzzles for the caches in this series. These files are not required to solve the puzzles, although they may be useful to you for both this cache series and other puzzle caches you solve. As the cache owner, I represent that these files are safe to download although they have not been checked by Groundspeak or by the reviewer for possible malicious content. Download these files at your own risk.


The goal of decyphering puzzle is to reveal the hidden message/coordinates. The cache title, description, hints, or hidden information may give clues as to what the cipher and key are. Quickly scan the encypted message and look for things that stand out such as strange fonts or groupings of numbers. These may give you an eduated guess as to what cipher is being used. Don't be afraid to experiment with different ideas. Not every attempt at decryption will yield a plain text message.

Remember that the end goal will be a set of coordinates. Look at what is encrypted. Is there any way to decrypt the beginning word to north or three, which would be common for most caches in our area? For example, if the beginning of some encrypted text would be FGJLZ LZJWW, we could assume that some sort of substitution cipher was being used. Since we see the second encrypted word ends in ww, we could make our first hypothesis that W = E, and the second word is THREE. Since the first word ends in JLZ, we can decypher that as fgRTH--probably a good indication that the first word is NORTH.

Having said that, of course, puzzle creators will omit punctuation and spaces, and possibly add extraneous text to make it harder for you to solve.

If the information is just a single list of numbers and they don't match any of the numbering systems described below is the total number of chacters evenly divisible by 15? If so, break down the list with whatever the quotient is and each of those numbers should yield a portion of the coordinates.

Basic Codes and Ciphers

Codes and ciphers have been around for hundreds if not thousands of years. Julius Caesar (100 B.C. – 44 B.C.) used a very simple cipher for secret communication. He substituted each letter of the alphabet with a letter three positions further along. Later, any cipher that used this displacement concept for the creation of a cipher alphabet, was referred to as a Caesar cipher.

Cryptography has two different forms--codes and ciphers. Many people believe that these terms are interchangable, and to some extent they are. However, to be more precise, a code is a language that is invented to conceal the meaning of a message or make it easier to disseminate, while a cipher conceals the message by replacing and/or scrambling the message's characters that make up its text. The simplest form of a code is what is known as jargon code. A historic example of this the only unbroken code in modern military history--The Navajo Code Talkers. The Navajo would use terms for items that they encountered in nature that resembled military items. For example, "chay-da-gahi", the Navajo word for tortoise, meant tank. Codes can be very hard to break without a common reference point.

Another type of code that was popular for a while (but has fallen out of favor with the advent of smartphones) was the keypresses required for texting. If you see repeating digits, look at your phone and think what the letters would spell if you pressed that button x number of times. 777-444-6-7-555-33-2-77-7-444-33.

So, you ask, "How do I tell if the cache is using a code or a cipher?"

Unless the hider comes right out and tells you (such as these caches: PDF417 Barcode or UPC-A Barcode, you really won't know until you start researching the puzzle. More than likely you'll have a cipher or a combination of the two.


The code that is probably most familiar to people is the barcode--there's one on just about everything we buy. Although barcodes used in the retail industry can only contain the number 0 through 9, there are many other barcodes out there that can display just about anything you want. Two codes that are seeing widespread use are QR Codes and more recently Microsoft Tag. Unfortunately these two codes are incompatible with each other. While most barcode scanning software on smart phones can read a QR code, a special application from Microsoft is required to read the Tags. The way these work is different as well. Whereas QR codes store the information within the code itself, when a Tag is scanned, the application sends the tag information to Microsoft which returns the data.

Here is a sample QR Code (left) and a Microsoft Tag (right)

QRCode Microsoft Tag

Barcodes puzzles are usually very straight-forward puzzles to solve, assuming the hider didn't put further puzzles inside of the barcode. Simply scan the barcode and get the answer you're looking for.


Ciphers can be broken down into two basic types: substitution and transposition. Substitution ciphers are probably what most people are familiar with; each plaintext letter of the alphabet has a corresponding substitution encrypted letter. For example, given the following cipher alphabet and plaintext message:

plaintext alphabet  abcdefghijklmnopqrstuvwxyz

we could encrypt the message meet me at the CITO event to YCCS YC TS SRC NOSF CKCVS.

This type of substitution cipher (where the same cipher letter always represents the same plaintext letter) is known as a monoalphabetic substitution cipher.

The simplest form of this type of cipher is known as a Caesar shift which involves shifting the letters by one or more positions. The Little Orphan Annie Secret Decoder Ring from the movie A Christmas Story, was a simple Caesar shift decoder. Every cacher should be familiar with this type of cipher since the hints sections uses a 13 place Caesar shift (also known as ROT13). These types of ciphers are very easy to crack since there are only 25 possible substitution alphabets. All you need to do is try each one until one provides a decrypted message.

Our example above uses a randomized ciphertext alphabet, which although slightly more secure than a Caesar shift, it's still easily broken by simple frequency analysis, which is based on the fact that in a written language, certain letters and combinations occur at a higher frequency than others. For example, in English, the letters E, T, A, and O are most common, and SS, EE, TT, and FF are the most common repeats. Just with this knowledge alone, I can guess that the first word is probably _eet and gives me a good starting location to decrypt the rest of the sentence.

Cipher Disk

Other types of monoalphabetic ciphers include using different keyboard fonts to change the letters from one form to another. Although these are easy to solve, they usually require a lot of tedius work doing the translation. Since most web sites cannot display the fonts natively, the hider will type out his message and then capture it to an image file to post in the cache. Since it's an image, the solver cannot simply copy and paste the information into a translator.

Here is the phrase "take me geocaching" in various keyboard fonts.

Font take me geocaching
American Sign Language American Sign Language
Braille Braille
Dwarvish Dwarvish
Morse Code Morse Code
Pigpen Cipher Pigpen Cipher
Wingdings Wingdings

Although they may not appear as such on first glance, numbering systems such as binary, octal, and hexadecimal are just another form of a substitution cipher--each character can be represented numerically. You should be able to find charts online that will convert the numbers from one numbering base to another. Microsoft Excel or any other spreadsheet program can make quick work of these puzzles, once you figure out what numbering system is being used to represent the data. This chart will give you an idea of what numbering system is being used:

Numbering System What you see How to decode using a spreadsheet
Binary 1s and 0s Break string into cells of 8 characters each.

Use the Char(Bin2Dec(x)) functions.

Octal 0 through 7 Break numbers into cells of 3 characters each.

Use the Char(Oct2Dec(x)) functions.

Hexadecimal 0 though 9

A through F

Break numbers into cells of 2 characters each.

Use the Char(Hex2Dec(x)) functions.

Base64 All characters

Usually ends with 1 or 2 equals signs (=)

There are public domain functions available,

however, it's easier to use an online decoder.

As you can see, there are many ways to conceal coordinates just by using simple substitution. In our next lesson, we'll cover polyalphabetic encryption, in which a plaintext character can be represented by multiple encrypted characters. In the meantime, here's a puzzle that will utilize what we've covered in this series up to this point.

This Cache

North Coordinates



West Coordinates



Additional Hints (Decrypt)

1. Qvtvgny gvzvat vf bireengrq
2. Byq aniny pbzzhavpngvba zrgubq

Decryption Key


(letter above equals below, and vice versa)



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Last Updated: on 11/2/2017 2:44:03 PM Pacific Daylight Time (9:44 PM GMT)
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Coordinates are in the WGS84 datum

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