Mystery Cache

Crouching Panda, Hidden Venona

A cache by Team Mumu Send Message to Owner Message this owner
Hidden : 11/1/2008
In New York, United States
Difficulty:
4.5 out of 5
Terrain:
2 out of 5

Size: Size: small (small)

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Geocache Description:

This is a puzzle cache. The given coordinates are for the parking area. Solve the puzzle, then take a short hike and go find the cache.


The Puzzle:

We have been tracking a gang of thieves, code named Big Fish. Intercepted messages strongly suggest that a cache of valuable items has been hidden in deep cover in the woods of Westchester County.

As described below, the Big Fish Gang communicates the coordinates of secret locations using a code book and a one-time pad. Although one-time pad ciphers are normally unbreakable, in this case the same one-time pad was used to send two messages, giving us an opportunity to crack the code. In addition, we have recovered a copy of the Big Fish code book. Your job is to crack the code and find the treasure.

Here is the first cipher text:

67009 48105 64953 07924 08589 35281 46882 61109 02346 65584

Here is the second cipher text:

05590 79658 93473 93753 25647 53170 06502 75509 30954 93151


Here is the code book:

UTM 20778
WGS84 68269
degrees 11110
east 58357
easting 47456
eight 08452
eighteen 56803
eighty 56546
eleven 85037
fifteen 09196
fifty 61748
five 39526
forty 85323
four 21313
fourteen 66797

hundred 69032
latitude 26374
longitude 70801
million 40076
minutes 46054
nine 55090
nineteen 41126
ninety 94111
north 75158
northing 20844
one 33285
point 54772
seconds 04718
seven 07846
seventeen 51482

six 94052
sixteen 26383
sixty 12544
south 43346
ten 60800
thirteen 42177
thirty 56217
thousand 10930
three 66485
twelve 97308
twenty 11425
two 36060
west 98859
zero 42911
zone 44605



The decrypted coordinates will lead you to a decon container hidden under sticks within a multi-trunked tree. Total walk is less than a mile round-trip through a pleasant nature preserve with a few stream crossings. We encourage you to stay on the trails until very close to ground zero.

Background:

The Venona code is a double-encrypted system in which words are first converted into numbers by using a code book and then the numbers are scrambled using a one-time pad. Code systems that use a one-time pad are theoretically unbreakable if they are used correctly.

The first step in the Venona code is to look up the words of the message in a code book that maps words to numbers. For example, if the code book contains:

agency 91348
anything 63165
never 51076
no 11641
say 61089
such 14902

then the phrase "no such agency" would be converted to:


no such agency
11641 14902 91348

The second step is to apply the one-time pad. The one-time pad should be a completely random and unpredictable string of bits. Suppose the one-time pad contains the following "random" blocks:

61723 61135 45799

To complete the Venona encryption, write the encoded number above the one-time pad and add the digits one by one, without carrying. Thus, the final output would be:

encoded message   11641 14902 91348
one-time pad 61723 61135 45799
-----------------
final cipher text 72364 75037 36037

To decrypt the message, the recipient must also have the same one-time pad. Simply write the cipher text above the one-time pad and subtract, again without carrying:

final cipher text 72364 75037 36037
one-time pad 61723 61135 45799
-----------------
coded message 11641 14902 91348

The coded message blocks are looked up in the code book and the original message is reconstructed.

Crypto systems that employ one-time pads are theoretically unbreakable if they are used properly. But if the one-time pad is re-used, and the code breaker has access to two cipher texts created with the same one-time pad, then he or she can exploit the difference between those two cipher texts to reconstruct the original messages (plain texts).


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

Additional Hints (Decrypt)

[puzzle] Ernq nobhg ubj gur erny-yvsr Iraban pbqr jnf oebxra ol gur cerqrprffbe bs gur AFN.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)



 

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Current Time:
Last Updated: on 1/30/2017 6:12:29 PM (UTC-08:00) Pacific Time (US & Canada) (2:12 AM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum