Cryptography 501 – Lesson 2

The Cryptography Lesson cache series is a series of caches that is based upon varying difficulties of cryptographic knowledge and cracking ability. The 501 lessons are meant to be taken together.

This cache bears remarkable similarities to two caches that were put out by Ibycus. Thanks to Ibycus for letting me recycle the idea, especially since I had a great deal of pride for having solved the originals.

The basis of these two caches is the Solitaire Cipher, as presented by Bruce Schneier in a fictional work titled Cryptonomicon (and was originally called Pontifex.) It was designed around the idea of being an (almost) unbreakable cipher based on a deck of cards, with the general thought being that a secret agent caught with a deck of cards would seem innocent enough. (More information is at http://www.schneier.com/solitaire.html)

Solitaire was broken by Paul Crowley in 1999 – this means that it is possible to decrypt the message without having to use every possible key combination. Regardless, for the casual observer, Solitaire is pretty much unbreakable.

There are many different ways to implement Solitaire on a computer. The program that I used for this one is available at http://www.erobillard.com/Content/solitaire/ although you may not need it for this cache.

One of the main weaknesses behind any encryption algorithm, though, is human weaknesses. Someone may use a very simple password, such as “password.” Another possibility is that someone used a date, like the words that make up the date that this cache was hidden (as an example.) Still another possibility is that two different ciphertexts may exist that use the same keystream.

This cache is found at the encoded coordinates below:

ZPYVS KCMQL JYUYL IXOSI UTFBK UPLKZ UGUJG ZSWOD CYWSG HVSEJ AYGAV TADTA SSPPL OMOOQ YQCBZ MMJDQ LHTQT BCWFJ ZP

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