This is our second cipher cache in Bear Valley. The first was Enigmacache BV. Hopefully these puzzles are not only challenging, but educational and fun. So, for those who accept our Vigenère geocache challenge, I wish you good luck. There is nothing tougher than staying awake on those long nights solving these puzzle caches. For those who look at this and turn away in fear, as always, I wish you happy hunting of other caches.
The Vigenère cipher, was invented by a Frenchman, Blaise de Vigenère in the 16th century. It is a polyalphabetic cipher because it uses two or more cipher alphabets to encrypt the data. In other words, the letters in the Vigenère cipher are shifted by different amounts, normally done using a word or phrase as the encryption key.
For about 300 years, it was believed to be unbreakable, although Charles Babbage and Friedrich Kasiski independently determined a method of breaking it in the middle of the nineteenth century. The method uses repeated patterns in the text to determine the length of the key. Once it is known that the key is, say, 8 characters long, frequency analysis can be applied to every 8th letter to determine the plaintext. This method is called Kasiski examination (although it was first discovered by Babbage). Even though the method of breaking the Vigenère cipher had been published 50 years earlier, the cipher was widely held to be unbreakable until the 1920s.
To encrypt a message using the Vigenère Cipher you first need to choose a keyword (or key phrase). You then repeat this keyword over and over until it is the same length as the plaintext. This is called the keystream. If the key word could have constantly changed, rather than using it over and over, early code breakers using frequency analysis would not have been able to decipher the code. But today, given a long sample of ciphertext, a competent cryptographer (geocacher) can easily break the Vigenère code.
To solve this Vigenère cipher you will need to solve two riddles.
What am I??
First riddle.
It is difficult when I run, but easier when I sit. Don’t ask me any questions because I will not answer.
Second riddle.
iltw qdrw dxyc nayk xwaf elib okew ttcl lgya ajdm kwtl sexn omse zten pvwt ef.t xmhm gcix trjt jcxn yele cygf vadr kerm vhlx evt. tzph ipdw lxmi fgce pael pvrx tqlr hxfl sipx vayk ipta exlt yotp phuj ppcs iw .s eztf my!
Final solution.
Gvx mqagy qhvzqoaomla nxr Byvcefrfh apekrgbe nvbrgxcmazjc. Pgmeufsolvfok haymryvl ypdrzufxlavd Tchk rbh! Acp mqaj gvx jipnr.