Dicas para a resolução de "caches enigma"

http://www.geocachingnsw.asn.au/index.php/geocaching/finding-a-geocache/134-tips-for-solving-puzzle-caches.html

Puzzle caches are a great alternative to traditional geocache. But for many geocachers, they are too difficult or require too much effort.

This page has been written to give you some tips on how to solve those puzzle caches that might currently be beyond your reach.

It covers what to look for when solving a puzzle cache, some of the clever techniques used to hide clues and how to confirm you're on the right track.

This session was originally presented at the Geocaching NSW 2010 AGM event by founding president, Darren Osborne.

1. Look for patterns

A puzzle cache will typically require you to solve all the digits in the coordinates (15 in total), the minutes (10) or the decimal minutes (6). For example;

• AB CD.EFG HIJ KL.MNO - 15 digits
• S33 AB.CDE E151 FG.HIJ - 10 digits
• S33 26.ABC E151 04.DEF - 6 digits

Solving a 15-digit puzzle is easiest as you can use the degrees part of the coordinates to confirm you're on the right track (see next tip). Puzzles that require 10 digits are typically the hardest.

Armed with this knowledge, you should look at the puzzle to see if there are 6, 10 or 15 objects, items, words, phrases, lines, etc. in the cache description. This may be where the answer is hidden.

2. Study the 'fake' coordinates

Since mid-2008, puzzle caches require the starting, or fake, coordinates to be within about 3.2 kilometres from the actual geocache. In southern Australia, this equates to roughly ±2' (minutes) east/west and ±1.7' north/south. Typically this will also mean the degrees portion of GZ will be identical to the fake coordinates - unless it is close to a longitude/latitude line, which will narrow down your search for 10- and 15-digit puzzles.

For example, if the fake coordinates are S33 24.509 E151 02.677 and you need to solve AB CD.EFG HIJ KL.MNO, you can reduce this to S33 2D.EFG E151 0L.MNO and that D is 3,4,5 or 6 and L is likely to be 0, 1, 2, 3 or 4.

If the puzzle uses repetition – such as AB BB.ACA – this will help you even further.

Example:

The geocache’s starting coordinates are S 33° 46.800 E 151° 01.000

The puzzle asks use to find the cache with the following: AA° BC.DEF GHG° FG.ACG

We could quickly solve most of this as we know A=3, B=4, G=1, H=5 and F=0.

So now our puzzle have been reduced to this 33° 4C.DE0 151° 01.3C1

3. Substitutions

There are many ways to convert numbers and text into something that looks unintelligible.

Below are some examples. To crack the substitution code, look for repetitions and patterns (see tip).

Examples:

Actual coordinates:S 33° 46.975 E 151° 02.996

Morse Code
... ...-- ...-- ....- -.... .-.-.- ----. --... ..... . .---- ..... .---- ----- ..--- .-.-.- ----. ----. -....

Roman numerals
XXXIII XLVI CMLXXV CLI II CMXCVI

ASCII Codes in Decimal / Base 10
83;51;51;167;32;52;54;46;57;55;53;32;69;49;53;49;167;32;48;50;46;57;57;

Binary / Base 2
00100000 01010011 00100000 00110011 00110011 00100000 00110100 00110110 00101110 00111001 00110111 00110101 00100000 01000101 00100000 00110001 00110101 00110001 00100000 00110000 00110010 00101110 00111001 00111001 00110110

Octal / Base 8
14611037 71472024

Hexadecimal / Base 16
33121F E67414

4. Learn about ciphers

Not all puzzles will solve as numbers. Some spell out the coordinates as words, such as 'south three three ...' or 'south thirty-three', or provide other clues – ‘next to the trig point’.

Ciphers have been used to hide text for thousands of years. In fact the hints that are typically shown on geocache listing pages use the ROT 13 or Caesar shift-13 cipher. ROT5 is a simple numeric substitution cipher. Other substitution ciphers include: substitution, Keyed Caesar, and Pigpen or Masonic. These are all "monoalphabetic" ciphers, meaning that each incidence of any particular letter or number in the original message always encodes to the same symbol in the encrypted message.  

ROT13 cipher

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

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

A

B

C

D

E

F

G

H

I

J

K

L

M

Caesar shift-5

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

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

A

B

C

D

E

ROT5

0	1	2	3	4	5	6	7	8	9
5	6	7	8	9	0	1	2	3	4

Keyed Caesar

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

K

E

Y

W

O

R

D

A

B

C

F

G

H

I

J

L

M

N

P

Q

S

T

U

V

X

Z

Pigpen cipher

The first step to solving these ciphers is to use a technique known as frequency analysis. This involves looking at which letters, or combinations of letters, appear most frequently. For example, the letter E is the most commonly used letter in the English alphabet. If the letter J appears most often in the ciphered text, then you maybe able to assume that J represents E and the cipher could be a Caesar shift-5.

Also look for common combinations that look like THE, THREE, and AND. Other patterns include

• The two Es in the word THREE
• TY on the end of TWENTY, THIRTY FORTY etc.
• SEVEN and SEVENTY repeats E in the 2nd and 4th positions
• NINETEEN repeats one character in the 1st, 3rd and 8th places and another in the 4th, 6th and 7th places.
• COORDINATES is a relatively long 11 letter word that shows up surprisingly often in geocache ciphers and it has O repeated in the 2nd and 3rd positions so it can be easy to spot.

Examples:

UQWVJ VJKTVA VJTGG HQTVA UGXGP RQKPV VYQ PKPG QPG GCUV QPG JWPFTGF HKHVA QPG VYQ RQKPV PKPG UGXGP UGXGP

8-1 4-2 3-2 2-3 2-1 2-3 4-2 3-2 4-3 7-4 8-2 6-2 3-1 3-2 7-3 8-1 4-2 3-2 7-3 6-3 2-3 5-2

The topic of ciphers and codes fills volumes of textbooks; far more than we can even begin to outline here. But if you're interested in learning more, here are some related terms worth researching:

Affine	Columnar Transposition	Playfair
Atbash	Double Transposition	Polybius Square
Base64	Enigma	Railfence
Baudot	Keyed Caesar	ROT47
Bifid	Letter Frequency	Steganography
Caesar	One Time Pad	Vigenere

Also, at the end of this article is a list of useful websites.

5. Other coordinate systems

Some puzzles result in coordinates that are not in the commonly used 'degrees-decimal minutes' format. They may be decimal degrees (S33.5684 E151.1789), degrees minutes seconds (S33 24' 31'' E151 03' 12''), or other grid references (UTM55 12 1235).