Bitterroot Branch Trail  LbNA # 22950

OwnerRubberband Man      
Placed DateFeb 19 2006
CountyMissoula
LocationMissoula, MT
Boxes1
Found Byterpsechorean girl (Attempted)
Last UpdateAug 25 2012

Clues

This next box is called the Bitterroot Branch Trail letterbox. For our purposes, we’ll use just a segment of the trail, from its southern end point (near North Ave. W and Garfield St.) to the turnabout circle where it combines with the Riverfront Trail (near the Montana Natural History Center on Hickory St.).
Like last time, I’m encrypting the message necessary to find the letterbox. The message is as follows: ISRKD FQOLK ICECY BZVGC OXPYW AMSRK AGXJJ BXHRG BNVOL JQVGR JZJJY VVMSW VVFTI KVGWK GIFBU YYHMO LJFIM PFKFW BOCDG SBCEY RZKCH BDSSO EWNFA NYSRV KRMMH SSMFN PQMAX DCLPG QTNIJ OKKYN TOEPS ZMSUC IXNZP HSXMZ EYVZV INACE USUFC YIGFF FEXYW BCIIW IMZJP DRIHY BQDWP PQTZG BFTZX YSIUM CPVZJ ONHLI MMJZZ UTWXQ IGJFV EWDWP VXFLU ZJZWE SRDTL (grouped in five for convenience).
I just finished reading “The Cracking Codebook” by Simon Singh which details the history of cryptography and cryptanalysis. It’s a fascinating and surprisingly easy read, and I found several fun ciphers in it. To get the above message, I used the famous Vigenčre cipher. Created by Blaise de Vigenčre in the 16th century, this cipher uses twenty-six substitution alphabets, normally arranged in a 26 by 26 grid. Messages are easily coded and decoded using a key word. Without the key word, though, these codes are hard (but not impossible) to break.
To get the key word, simply walk the stretch of trail as described in the second paragraph. Count the number of streets you cross and multiply it by the number of permanent garbage cans you see right next to the trail. This number is the key word.
At this point, you can do one of three things: 1) you can ignore the search for the key word and crack it by hand (if anyone does this, please contact me), 2) you can obtain the key word and go to the website “http://math.ucsd.edu/~crypto/java/EARLYCIPHERS/Vigenere.html” which has an automated system for decoding a Vigenčre cipher with the key word, or 3) you can decode it by hand with the key word which requires you to make the 26 by 26 grid. In this case, the first few lines of the grid look like this, with a shift of one letter all the way down:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
BCDEFGHIJKLMNOPQRSTUVWXYZA
CDEFGHIJKLMNOPQRSTUVWXYZAB.
At the end, you should be able to read the alphabet along the top and down the left side. The key word’s letters are then matched up with the cipher text. The key word’s first letter is matched with I, the second with S, the third with R, and so on. When you run out of letters in the key word, repeat the key word until you have matched a key word letter to every letter in the cipher text. To break the cipher, take the first pair of letters (one key word letter and one cipher letter). Find the key word letter in the top line of the grid. Then go straight down the column until you find the cipher letter. Follow this row to the left until you reach the end of the line and that is the first letter of the real text. Repeat for all other pairs (I suggest you tackle this in a warm place).
I’d estimate that this letterbox might take anywhere from ninety minutes to several days, depending on which option you choose. It’s cryptography, history, math, and letterboxing all rolled into one! Now where else are you going to find that? Happy hunting!