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Breaking the Code to Find the Cache

written by: Misty Faucheux•edited by: Tricia Goss•updated: 6/10/2011

Certain caches require that you figure out a code before you can even get the hint for where the cache is. Learn why people add codes to caches and how to decode them using different ciphers.

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    Challenging Caches

    Most geocaching caches are relatively easy to find and understand. You simply input the coordinates of the cache and read the hints to help you locate the code. The hints are usually relatively easy to understand. It may read something like “look near the collection of rocks;" you simply need to find the rock collection and then search for the cache.

    Some caches, however, are a little more difficult to find. You need to break the code to get the hint. Geocaching code breaking is a fun way to challenge yourself if you are bored with the standard caches. You can also encode your own hints using different ciphers, increasing the difficulty of the cache.

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    Using Ciphers

    ROT13 Generally, geocachers use a variety of ciphers to make their code. The cache description will tell you what cipher they used to encode the message. Common ciphers are the Caesar, Vigenere and ROT13 ciphers. These all involve replacing a letter in the message with another letter, which is known as a substitution cipher.

    For example, if you use the Caesar cipher, the code for “the dog jumps" would look like this: WKH GRJ MXPSV. If you, however, use the ROT13 cipher, the same phrase would look like this: GUR QBT WHZCF.

    The way the letters look really depends on the type of cipher that you are using, so you always want to pay attention to the instructions within the cache. Some caches may be a bit more complicated, using several different ciphers within the same description.

    An example of this was on Geocaching.com. The author used the following ciphers:

    • Vigenere Cipher
    • Binary
    • Geocaching Decryption Key
    • Caesar Cipher
    • Base64

    What’s more than that, the author indicated that the keys are used in random order, so you not only have to figure out the code, you also need to figure which line of code goes with which cipher.

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    Decoding the Message

    You might be thinking that this may be a little too advanced for you. This is an abnormal code breaking geocache. Most caches only use one cipher, making it pretty easy to get the hint. Codes such as the one mentioned above are rare, and they are only for advanced code breakers.

    Some codes require that you have a key to break them. Many do not, but you should closely read the description to make sure.

    If you want to go after a cache that requires a bit of code breaking, you do not have to be a wizard at the task. There are many free online code breakers especially for geocachers. My Geocaching Profile has a code breaker for the Vigenere Cipher. This code breaker works by searching through the code and trying to determine the length of the key.

    It then looks for repetition of common words such as “the." Based on the estimated length of the message and the spaces between words, the code breaker then tries to determine the text. It does this based on multiple guesses.

    Another free code breaker is the Secret Code Breaker, which breaks the Caesar Cipher. You have to download the zip file to use this program.

    Both of these programs work in much the same way. You copy and paste the encoded message into the Key sections and press the Code Break or Key button. The program usually takes about one minute to decode the message.

    Once done, you will see the decoded message in the Message box.

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    Encrypting a Cache

    If you are the one hiding a cache, you can also use these programs to encode your message. You basically just do the opposite of above. You may only want to put in one sentence at a time. For example, for the Caesar Cipher, you would follow the below steps:

    1. Type in or paste the phrase or word that you want to encode in the top box.
    2. Click the Encipher button.
    3. Pick a Key.

    The newly encoded message will be at the bottom. You then just save the encoded message and add it to your geocache description.

    Geocaching code breaking is a fun way to add challenges to your geocaches. Always figure out the message before you go. You do not want to be standing near the cache trying to figure out the cipher, especially if you need a code breaking site to assist you with the task. You might not have any Internet connection or cell phone service near the cache. In addition, you do not want to be dealing with an especially difficult code under the noonday heat.

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    References and Resources

    ROT13.com: What is rot13?

    Geocaching.com: Code Breaker - Multicoded

    Downloadable Caesar Cipher Software: Secret Code Breaker

    My Geocaching Profile: Vigenère Cipher Code Breaker