This cache was placed by BaseOverApex (BoA) in January 2012 when Gilly Court was beginning to be developed.
We have accepted BoA's invitation to adopt this cache to keep it alive because of the significant history involved. We have retained as much as possible of the original description and BoA's photographs, of the deserted station, are still in the gallery.
The co-ordinates given are where you will find the first part of this two-part puzzle cache.
Be prepared to spend some time on this one, and possibly make a second visit. You will find a smartphone useful.
Background
Sometime in the late 1930’s a government building and its infrastructure arrived among the farms and green pastures which make up the town land of Ballyhanwood.
This was a radio listening station, established by the GPO during the run up to WWII. At the time, of course, it was one of those places of which everyone in the local area was aware, but no-one really knew anything about it. From the beginning the station has been associated with all sorts of rumours and wild tales. To this day, those who know folk who worked there report that they always said "I know nothing about it" with a little smile.
This is believed to have been one of two so-called "Y-stations" in Northern Ireland (the other being at Ramore Head, Portrush). A search of the internet will provide some interesting information, for example:-
Link.
The building lay vacant on the site from 1979 until 2009, when it was developed into apartments. Today the gateposts at the entrance to Gilly Court have two plaques giving information about the site during its glory days. It is believed that the combined efforts of the "Y" service and the code breakers shortened WWII by at least two years and saved the lives of over 14 million people!
The Cache
Messages intercepted at a listening station might have been encrypted, so it seems only fitting that the actual cache co-ordinates be encrypted.
In Geocaching, we apply a form of encryption to the hint (we call it rot-13). This is a form of the Caesar Shift cipher (Wikipedia Article), where the plaintext is shifted (rotationally) by 13 places. It is an easily broken cipher (even if the shift is unknown) and is used in our context only as a simple mechanism to mask spoilers.
An extension to this system is to use "polyalphabetic substitution." That is the application of a different amount of rotation to every character of the cipher. The amount of rotation to be applied to each character is given by a key.
Each letter in the plaintext and the key are assigned a value (A=0, B=1, C=2, etc...) If the first letter in the key is "A", the first letter of the cipher text will be encrypted using rot-0. If the first letter in the key is "B", the first letter of the cipher text will be encrypted using rot-1, etc. Given a key text, then, a simple mechanism for encrypting a plain text is to apply a Tabula Recta (Wikipedia Article).
If the key contains random characters, it is known as a one time pad and the cipher is impossible to crack using traditional frequency counting techniques. The major flaw with this encryption is that the key might become captured by the enemy.
At the co-ordinates given, you will find a key. This key is not encrypted, rather it is encoded, using a well-known and quite modern technique.
Below, encrypted using the key and method described above, are the final co-ordinates of the cache:
OZVMJMTJRNFFESOIZTLPWRWIIDZQSN
TWZMLITYBFPWBZAHSUTSKPJGIWGNCI
CHFFBUJRBPLASGCTWYVCWXXLYWGM
Please note that the hint text will NOT help you to find the first part of this cache, but if you’re unable to find or decode the first part, it will give you a clue to the decrypting the above message. This allows cachers without smartphones to find the cache by cracking it with "brute force." It IS possible, but awkward, to find the second cache without finding the first part and without looking at the hint. Please don’t reveal it unless you’re really, really stuck. I’d be keen to hear from anyone who decides to go straight to brute-forcing the decryption without knowing the key!
You can check your answers for this puzzle on Geochecker.com.
Please be careful when parking and bring your own pen.
