Cryptology 101: Caesar Mystery Cache

Background

Cryptology has fascinated and intrigued me since my grade school days where I spent hours encrypting and decrypting notes with my friends. Cryptology lends itself nicely to puzzle caches so I'm starting a Cryptology series of puzzle caches with the goal of demystifying some of the techniques used for solving and creating puzzle caches. There are a variety of different types of encryption, many of which I will cover in this series.

This puzzle cache uses a simple substitution cipher. Use the clues found on this cache page to figure out which substitution cipher was used to encrypt the cache location. Once you have that information, deciphering the ciphertext is straightforward.

In cryptography, a substitution cipher is a method of encryption by which plaintext (i.e., puzzle coordinates or other text) is replaced with ciphertext according to a regular system. The receiver deciphers the text by performing a substitution. The trick is to figure out the substitution formula. Substitution ciphers are easily decrypted as they are susceptible to frequency analysis, brute force and word analysis. Frequency analysis is the study of the frequency of letters or groups of letters in a ciphertext. A brute force attack is a method of defeating a ciphertext by systematically trying a large number of possibilities. With word analysis, the receiver looks for common words that could appear in the text. In the case of geocaching, common words to look for are "north", "west" along with numbers. In many cases, deciphering a cache is made up of a combination of the aforementioned techniques.

An example of a simple substitution cipher is ROT13 (rotate by 13 places) which is the encryption method Groundspeak uses for encrypting hints on a cache page. ROT13 is not the cipher used in this puzzle cache.

Puzzle

Decipher the following substitution cipher to obtain the coordinates to where the cache is hidden. Good luck and have fun!

I'd love to hear about what technique(s) you used to solve this puzzle so feel free to leave a note in your online log without any spoiler information. Here are some possible ways to solve this puzzle:

• Substitution logic from knowing the formula of the cipher (but please don't reveal the name of the cipher)
• Frequency analysis
• Brute force
• Word analysis
• PAF
• Other

You can check your answers for this puzzle on Geochecker.com.

Cache

Ground zero is accessible by hiking or boating along the Exeter River. There is a first-to-find prize of a Dunkin Donuts gift card and an activated FTF coin to place in your next cache hide. Bragging rights will be given to the FTF by Trail #1, FTF by Trail #2, and FTF by boat. Please rehide the cache so it is not visible.

The hike into the cache is about 1.25 miles from the suggested parking coordinates, along mostly flat terrain on well marked trails. I personally like this side of the trail system as it is used less often than the other trails. The woods are surprisingly quiet of human activity, considering its proximity to the center of Exeter.

The trails are firm soil with exposed roots but are suitable for hiking, cross-country running, mountain biking or snowshoeing. The trails are wet and mushy in the low areas in the spring and after a heavy rain. There are a few bridges along the trail which span the areas that are wet year-around along with numerous make-shift, Indiana Jones style bridges which will help keep your feet somewhat dry. You may need to do a little bushwhacking here and there to avoid the water. In the warmer months, expect and plan for ticks, mosquitoes and poison ivy.

After your scenic hike into the cache area, you will be rewarded with nice views of the Exeter River in a quiet area of Exeter. If you like to swim, pack a bathing suit and towel and try out the river. I would also recommend trying out the natural bench near the cache. The downed tree by the side of the river provides a comfortable spot to relax, sign the log and enjoy the view.

Along one of the trails is a cemetery with two graves -- Susannah Holman Brown and one of her children (see the posted waypoint for the exact location). Please be respectful of this area. I did some research on Susannah and found this poignant poem dedicated to her:

Poem for Susannah Holman Brown
1785-1812

Oh, Susannah, resting in this quiet wooded place,
Pine needles, ferns, moss, and leaves
Are gentle ground as I walk into your sacred space.
Others on this Mother's Day sought out these two lonely graves,
Leaving Spring's emblems upon your arch-shaped stone
Where you and your child have slept as your farm returned to forest
And your first babe, motherless, finally full grown,
Remembered and passed on your memory, marking where you rest.
What is it like to be under the moon, the stars, the downy snow,
Blessed by walkers on this trail, who stop for just a while
To wonder why your grave is here, to never have a chance to know
The wife you were, nor the child who lived to see your smile?
These flowers change the rhythm of so much verdant green –
From those who stop to send you love amid your endless dream.

Pam Bourgeois
2003

FTF