Weekly Challenges

Challenge 12: Nigh Impossible

Here’s Challenge #12 for November 8, 2017.

Today, I wanted to learn about homophonic substitution ciphers. These ciphers aim to thwart frequency analysis by assigning multiple ciphertext symbols to each plaintext symbol. The higher frequency of a letter, the more cipher symbols it is assigned. One of the most famous examples of homophonic ciphers is Rossignols’ Great Cipher.

For my homophonic cipher, I wanted to closely-match the frequency of each letter. For example, the letter E has the highest frequency at 12.7 percent. If my cipher used a pool of 100 numbers, 13 of those would represent the letter E. But if I were to use only 100, what would I do with letters such as Z, which have less than 0.1 percent frequency? In order to represent these low frequency numbers, I had to increase my pool to 1000 numbers. So now, the letter E is represented by 127 different characters!

My symbols-to-letters distribution corresponds fairly closely to the characteristic distribution. The letters Q and Z each have 1 plaintext symbol. The letters M and W each have 24. The letter A has 82.

Such a large pool of symbols means that cracking this cipher without hints will be nigh impossible. I’ll reveal a few hints now and occasionally update the post with further clues. I expect this to be the most challenging cipher I’ve yet posted on CodeAWeek.

Each 4 digit number represents a letter in the English alphabet. Here’s the ciphertext:

0385 0376 0275 0591 0106 0856 0957 0894
0808 0997 0830 0801 0511 0556 0648 0995
0295 0587 0756 0686 0983 0169 0207 0353
0111 0447 0545 0168 0162 0294 0632 0475
0937 0951 0996 0444 0549 0410 0652 0939
0701 0936 0312 0231 0770 0186 0898 0458
0374 0507 0479 0423 0017 0198 0323 0550
0306 0233 0460 0702 0625 0583 0708 0004
0524 0205 0305 0037 0038 0677 0351 0465
0299 0092 0753 0293 0018 0775 0100 0654
0311 0938 0108 0612 0496 0118 0495 0698
0665 0201

Notice that no number repeats, which tells you that the plaintext has one or no occurrences of Q and Z.

Here’s the first big hint, which will hopefully take this cipher from nigh impossible to nearly nigh impossible. Here are all 90 symbols for the letter T:

0268 0930 0367 0715 0294 0709 0688 0010 0704 0858 0266 0306 0886 0438 0502 0655 0595 0885 0673 0995 0708 0468 0142 0040 0078 0863 0558 0399 0210 0436 0091 0090 0952 0029 0701 0417 0264 0092 0175 0861 0250 0170 0605 0729 0681 0318 0221 0263 0077 0597 0197 0686 0430 0650 0542 0864 0805 0693 0505 0017 0924 0488 0625 0543 0362 0099 0849 0682 0946 0192 0422 0012 0239 0312 0194 0184 0347 0277 0064 0425 0557 0753 0156 0663 0877 0481 0830 0434 0410 0827

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery each week. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 11: The Right Type

Update 2017-11-09: We have a winner! Puzzling.Stackexchange user Kayzeroshort solved the puzzle today. It took him 12 days, which means he is awarded 12 points on the Leaderboard. View the solution here.

Here’s Challenge #11 for October 27, 2017.

Today’s cipher is a method I created based on a known method, although it is likely that someone else thought of it before me. Here’s the ciphertext:

YGWCSD QDCHVF WCLEZJ CHCTJQ YUEOYG YSE,GY KYJXDZ KYCYEP IFKWGW
TIHOEP CHRTJR DOCRTU YGY,HB PEDWUC GWU.QD ;WRTDR BESDOY ZDMNUC
SFQDCH RKWCH. POXHQO QFYOY. YPSAYR QFYHYG Y,HGIT YGRT

I’ll give you three clues:

    1. The method is a spinoff of the famous method used to encode Challenge 10.
    2. The punctuation in the ciphertext encodes letters in the plaintext. (There is no punctuation in the solution.)
    3. The following text is not a deciphering tool but a clue that will point you in the right direction. What came after this?
      3 5 7 9 N O P Q R S T U V W X Y Z
      2 4 6 8 . A B C D E F G H I J K L M

New hint! (Updated 2011/11/08): The solve method lies at your fingertips.

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery each week. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 10: No Cheating

Update 2017-10-22: We have a winner! Stackexchange user M Oehm solved the puzzle today. It took him one day, which means he is awarded 1 point on the Leaderboard. (The puzzle is older than one day, but I just posted it today on Puzzling.Stackexchange, and that’s where he solved it.) Read the solution here.

Here’s Challenge #10 for October 15, 2017.

NO CHEATING

Today’s cipher is a famous cryptographic method known for its economy, ingenuity, and difficulty in cracking. Its inventor created all sorts of cool things, including musical instruments, a timepiece especially useful at the North Pole, and the earliest ancestor of the Oculus Rift. Aside from this cipher, which does not bear his name, he is most famous for co-inventing a means of communicating at long distances.

The key to unlocking the mystery is his name. Good luck!

The ciphertext is:

WXYCNW LAHWNZ WONSNI LEXAPE OSMWOW RCSRQC AZ

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery each week. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 9: The Collection

Update 2017-10-21: We have a winner! Stackexchange user Eedrah solved the puzzle today. It took him 13 days, which means he is awarded 13 points on the Leaderboard.

Here’s Challenge #9 for October 7, 2017.

THE COLLECTION

My great uncle from Atlanta died last month, and my family drove there to attend the funeral and prepare his house for an estate sale.

When I was cleaning his office, I found a strange note.  I’ve stared at it for hours, and I just can’t figure out what it means. Maybe you can help. I am attaching a copy at actual size. I added a 1″ mark on the side, so if you print it, you can make sure it’s properly sized.

The note wasn’t the only strange thing in his office. Every square inch was filled with Coca Cola memorabilia — posters, newspaper ads, toys, and unopened bottles.  By far his largest collection was of 12 oz. Coke cans from different eras. There must have been hundreds!  And apparently when he wrote the note, he was thirsty. Right beside it was a Coke can, the only empty one in the room.

Other than the Coke memorabilia, the room looked like a typical office. On his desk were pencils, a spiral notebook, a cloth tape measure, Scotch tape, and a pair of scissors, though I doubt most of this has anything to do with the note.

Maybe it’s all just gibberish, or maybe there’s more than meets the eye. Can you help me solve the mystery?

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every week. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 8: The Cardboard Box

Update: September 29, 2017. This challenge was solved by Neremanth on the Puzzling.StackExchange forum. I’ll be posting the solution soon.

Here’s Challenge #8 for September 28, 2017.

THE CARDBOARD BOX

Today’s cipher is a one-step monoalphabetic substitution. The key to solving it lies within the following poem:

A clerk gave me a cardboard box
that now I give to you
It once held t-shirts, jeans, and socks
It now holds one left shoe
Take out the shoe and put it on
then head to liquor store
Now drink the whiskey till it’s gone
and then drink thirteen more
Pack my box with liquor jugs,
five dozen — all in all
Checkout with clerks and give them hugs
and then go have a ball
Don’t wreck your car, though you are wrecked
and don’t heed every sign
Dead ends, some lead to misdirect,
save line and half a line

And here is the ciphertext:

SOMRF XCIAJ QELYQ DWFHU GQVMJ SOMTP NZKQB

Since the cipher is mono-alphabetic, some people might be able to crack it without relying on the poem. But to win this, you must decode the message AND explain how the poem unlocks it.

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every week. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 7: A Simple Substitution

UPDATE 2017/09/23: This post has been solved! View the solution here.

Here’s Challenge #7 for September 20, 2017. (Published a bit late. My apologies.)

A SIMPLE SUBSTITUTION

Today’s cipher is a one-step polyalphabetic substitution that’s not a Vigenère. If you know how to count, you shouldn’t have a problem figuring out this method.

The answer is a quote from a famous book on arithmetic.

The ciphertext is:

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

Good luck!

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every Wednesday evening. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

Challenge 6: Google Earth Treasure Hunt 2

Here’s Challenge #6 for September 13, 2017.

GOOGLE EARTH TREASURE HUNT 2

I’ve spent many a night browsing through Google Earth in hope of solving Forrest Fenn‘s treasure hunt. I would spend hours zooming in on mountains and scrolling down rivers in Montana, Wyoming, Colorado and New Mexico. While I never cracked the riddle, I had a blast learning about the Rocky Mountains. Google Earth’s power lies in its ability to make geography an adventure. There’s so much to learn by simply picking a land mass at random and zooming in.

That’s the impetus of my Google Earth Treasure Hunts (GETH). My first prompted you to find 4 places by solving 4 separate riddles. But it didn’t recreate the thrill of hunting for objects on a map.

For my second GETH, I hope to partially recreate the fun of zooming in on mountains and scrolling down rivers while learning about geography.

First things first. This challenge uses decimal latitude and longitude coordinates (ex.  29.978763°, 31.134297°) as opposed to degrees minutes seconds (ex. 29°58’44.64″N, 31° 8’3.05″E). To get Google Earth to show decimal values, click Tools, then Options. Under the tab called “3D View,” under the heading “Show Lat/Long,” check “Decimal Degrees.”

This challenge cuts off decimal degrees after two decimal digits. Don’t round. Just cut off. So 29.978763° would be represented as to 29.97. I debated whether or not I should use rounding, but cutting off makes searching a coordinate square much simpler.

At times, I’ll ask you to add or subtract numbers to a coordinate. Let’s say the coordinates are 29.97, -6.64 and I say, “Subtract 4.45 from the longitude coordinate.” The longitude is the second of the two coordinates, -6.64. Notice that this example is a negative number. -6.64 minus 4.45 equals -11.09.

Without further ado, here’s the challenge.


  1. This white plastic jungle feeds nations and can be seen from Earth’s orbit. Find it using Google Earth.
  2. Zoom in on that place and find the largest body of water within it. Find the bridge crossing the middle. Take the coordinates of the center of the bridge. (Cut off the numbers after two decimal digits.)
  3. Subtract 0.64 from latitude (the first coordinate.) Subtract 2.61 from longitude (the second coordinate.) Enter these new coordinates into the Google Earth search bar and press enter.
  4. See the big rock? Find the pillars and note their namesake.
  5. Convert this name into numbers where A=1, B=2, C=3, etc. Don’t put a 0 in front of single digits. (Ex. F = 6, not 06.)
  6. Make new coordinates with these numbers. The third letter of the name is the latitude coordinate before the decimal. The fourth letter is the latitude coordinate after the decimal. The fifth letter is the longitude coordinate before the decimal. The sixth letter is the longitude coordinate after the decimal.
  7. Now, subtract 36.22 from the latitude. Add 4.73 to the longitude.
  8. Enter these new coordinates into the Google Earth search bar.
  9. What do you see here? Now, find its South American rival.
  10. Once located, find the nearest river and follow it downstream until it converges with another river.
  11. Surrounding this point are three similar-looking monuments  Take the coordinates of the one painted green and yellow. Write them down. We’ll need them in a moment.
  12. Continue following the converged river northward until you pass a bridge and an island. If you see a dam, you’ve gone too far.
  13. Just after the island, search the river’s eastern coast for a large bronze deity turning his back on standing brethren. Take the coordinates of the bronze deity and write them down.
  14. Now, take the latitude of the yellow/green monument. This will be our new latitude. Take the latitude of the bronze deity. This will be our new longitude.
  15. Switch the +/- in the new latitude and longitude coordinates. If it’s a positive number, make it negative. If it’s negative, make it positive.
  16. Subtract 3.26 from the latitude. Add 6.15 to the longitude.
  17. Find the historical site within these coordinates. Where are we? If you are the first to send me the name of this place and an explanation of how you got there, you win.

In my next GETH, I hope to tie all of the locations into an overarching theme. Look for that in an upcoming weekly challenge.

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every Wednesday evening. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com.  If you guess incorrectly, you must wait three days to send another guess. (You can send sooner, but I will hold off replying to subsequent guesses until the 3-day window is over.)

Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

If this challenge is too hard or too easy, check out Challenges 1, 2, 3, 4, and 5.

— Tony Youngblood

UPDATE 2017/09/14: I cross-posted this puzzle on Puzzling.Stackexchange the day after I posted it here. There, in a matter of hours, Sleafar solved it. The challenge is now closed, but feel free to discuss in the comments. View the solution here.

Challenge 5: A Vigenere Cipher

UPDATE 2017/09/23: This post has been solved! View the solution here.

Here’s Challenge #5 for September 6, 2017.

A VIGENÈRE CIPHER

In Challenge#2, we featured a Caesar Cipher, the most well-known monoalphabetic substitution cipher. “Monoalphabetic” means that each plaintext letter only has one corresponding ciphertext counterpart.

Today, we’re featuring a Vigenère Cipher, which is the most well-known polyalphabetic cipher. “Polyalphabetic” means that each plaintext letter does not have a one-to-one correspondence with a ciphertext letter. The letter “D” may be enciphered as “H” in one spot and “X” in another.

The Vigenère Wikipedia page is a good starting point to learn more about this fascinating cipher. Jim Sanborn used the Vigenère to encipher at least two of the panels on Kryptos.

Here are a few characteristics of my Vigenère:

  1. It uses the standard English alphabet in the rows and columns. (ABCDEFGHIJKLMNOPQRSTUVWXYZ)
  2. The key is 10 characters or fewer.

Here’s the ciphertext:

EHAQW DPEZR RWAHT NELTN OHMJE IAWAJ OYNOY HSYPK TGAWW DOJSN SICZY AJRTS ETYHO KRIWO AAPDB FTRAS TRHLZ FHEHT WLBOQ QOYES ECFTZ NOLET DSXFM PETMA

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every Wednesday evening. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

— Tony Youngblood

 

Challenge 4: A Google Earth Treasure Hunt

UPDATE 2017/09/23: We have winners! This challenge was solved by Humn, Euchre Mutt, Gareth McCaughan, and Irishpanda. The challenge is now closed, but feel free to discuss in the comments. View the solution here.

Here’s Challenge #4 for August 30, 2017.

A GOOGLE EARTH TREASURE HUNT

For today’s challenge, I’m trying something new: a Google Earth treasure hunt.

For this hunt, you don’t need a shovel. You don’t even need to leave your house. All you need is Google Earth (or Google Maps) and the mind of a treasure hunter.

This hunt was inspired by Forrest Fenn’s hidden treasure and the 1979 treasure hunt picture book Masquerade.

Imagine that I’ve locked away ten million dollars in a high security vault.* The vault is protected by a digital keypad. The correct combination is comprised of decimal latitude and longitude coordinates, accurate to two decimal points. To unlock my vault, you must identify four places in the world and correctly enter their coordinates. For example, if one of the places is the Great Pyramid of Giza, the full coordinates would be: 29.978763°, 31.134297°. We don’t need to be THAT precise, so we round to two decimal points to get: 29.98°, 31.13°. That’s the format I’m looking for when you submit your answer

To get Google Earth to show decimal values instead of degrees/minutes/seconds, click Tools, then Options. Under the tab called “3D View,” under the heading “Show Lat/Long,” check “Decimal Degrees.”

Here are clues to the four locations. Can you figure out where I’m talking about?

  1. Here, a babirusa lies in wait, as it has done for the last 40,000 years. It is the oldest of its kind in the world (that we know of as of this writing).
  2. In this wondrous museum that isn’t in England, Germany, or the United States, you can hear violins, drums, flutes, pipes, whistles, bells, chimes, pianos, xylophones, and even full orchestras. You can see the instruments being played, but you won’t find people doing the playing.
  3. General Sherman may be the largest of his kind, but who has the farthest reach? (Outward, not upward.)
  4. This (sort of) cave trail is home to the fairies, located within a tourist attraction in the United States that is advertised for hundreds of miles as the place you simply must SEE.

The winner is the first person to send the correct coordinates, numbered 1 through 4 to codemaster@codeaweek.com. You must guess all four correctly to be considered the winner. If you send a guess and it’s wrong, you must wait three days to send the next guess. (You can send sooner, but I will hold off replying to subsequent guesses until the 3-day window is over.)

If you’re not sure how to find latitude and longitude on Google Earth, watch this tutorial.

To ensure that you get the exact coordinates, pull them from the Google Earth pin of the place. In the above pyramid example, you would find the “Great Pyramid of Giza” pin and use that exact location’s coordinates.

Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code. You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

— Tony Youngblood

* I don’t really have ten millions dollars or a vault. I barely have a checking account. The only prize is the thrill of the solve and your name in the Code A Week record books.

Challenge 3: A Simple Calculation

 

Update 2018-01-04: We have a winner! Euchre Mutt solved the puzzle today. The puzzle remained unsolved for a whopping 134 days … a site record! … which means he is awarded 134 points on the Leaderboard. Euchre already had the number one spot by solving previous challenges. With the win new, it’s going to be VERY HARD to catch up to him! View the solution here.

Here’s Challenge #3 for August 23, 2017.

A SIMPLE CALCULATION

With this cipher, I hope to add a new encryption method to the playbook. If you formulate the correct hypothesis, you just might take away the prize.*

Some clues:

  1. It’s a substitution cipher.
  2. The ciphertext is 102 characters. The plaintext solution is 34 characters.
  3. What is 102 divided by 34, and what does that tell you?
  4. The plaintext solution is a quote from a famous mathematician.

The ciphertext is:

LCFBPDLED HCJJKAHFF TSNIGANRK GMBHJMQCO XETSSRVLZ CFDZOWVLP JJKFSRPCK BXFIVPWJO RSLYNXFSD HRHAOKQQK IJAEPFBUI QPZ

With CodeAWeek.com, I hope to release one cipher, puzzle, or mystery every Wednesday evening. Anyone can attempt to solve. The winner is the first person to send a correct solution and a description of the solve method to codemaster@codeaweek.com. Once a correct solution is e-mailed, I will publish a follow-up post, congratulating the winner and revealing the secrets of the code.

You may post questions or theories in the comments, but DO NOT POST SOLUTIONS. E-mail them to codemaster@codeaweek.com.

* “Prize” being figurative. Right now the only prize is the thrill of the solve and your name in the Code A Week record books.