History
The one time pad system of message encryption has been around since the late 1800s. When used properly, it is the only known method of encryption that cannot be cracked. In practice, field agents would be given a "pad" of keys that consisted of randomly generated characters. There were systems in place to dictate which key would be in use on any given day. Without access to the proper key, decryption of the message is mathematically impossible. In order to send messages to agents in the field, agencies often used shortwave radio broadcasts (called numbers stations) that could be picked up on commonly available receivers. The messages sent could contain information about a contact the agent needed to meet with, a mission that needed to be completed, or any other sensitive information. This system was heavily utilized by many nations during the Cold War era. But, there are still stations broadcasting today utilizing this same method.
Cache Particulars
The published coordinates will get you within range of the station broadcasting an encrypted message. The message is broadcast on a loop, daily, between the hours of 6AM and 11PM. The final location is accessible 24/7. The message is encrypted with a one time pad key (included at the end of this description). Once you've tuned into the station on your radio (87.9FM), you'll need to copy down the message, and decrypt it using the same one time pad key.
Bring your own pencil or pen. You're a spy. You should carry one. ;-)
Helpful Information
The methods for encryption and decryption utilize addition and subtraction, respectively. Each alpahabetic character is assigned a numerical value. In this case, we'll use A=0, B=1, C=2, and so on, until Z=25. To ENCRYPT a message, you add the key character to the message character you wish to send. To DECRYPT a message, you subtract the key character from the message character you received.
During encryption, you may find that adding your message character and the key character together gives you a number greater than 25. If this happens, simply subtract 26, and use that number.
During decryption, you may find that subtracting the key character from the message character gives you a negative number. If this happens, simply add 26 to the negative number, and use that number.
***Agent Eyes Only***
Before you were sent on your covert spy mission, you were given the following one time pad key to decrypt messages sent from the agency.
LNIGY MKCCO QCHIC NOWZO
MMPUG AAZCP LWPZV DBOKH
LRQMR YTOFP QIJYN ISZUU
HMKNP WXWJN AAWGW BUSAK
ESVUO SDTLD HUNPT TXOPC
UKGVL IPVTH IOQFI AOILZ
LWWJX JRRLV OHVSI JGGSM
TEVRF RVSBW CMZTG KNMJY
RKEFL FAGCU IXPNC BCNOG
BDUCM XAWXQ BSIUM RPJTC
TGPJQ RXXBJ NSPVN PDXVP
BOYHE OFDNT MBBTN MCUHU
Character Values:
A=00 N=13
B=01 0=14
C=02 P=15
D=03 Q=16
E=04 R=17
F=05 S=18
G=06 T=19
H=07 U=20
I=08 V=21
J=09 W=22
K=10 X=23
L=11 Y=24
M=12 Z=25