One for the puzzle nerds

Posted on Posted in Everything, Software Testing

In the spirit of recent puzzles/challenges, I thought I might throw in one of my own. In high school, my class was given an exercise to come up with a coded message that the rest of the class would have to work out the cipher to.

I didn’t take it that seriously at the time and put in some sort of lame effort at home that afforded me the most time in front of the Commodore-64 instead. Most other kids did the same. Clearly the teacher had been hoping that someone in the class was a secret genius and would put together something brilliant. His disappointment when this did not occur was palpable.

I got thinking afterward that it was a wasted opportunity. I quite like puzzles, I like being creative, but I’d never put the two together. I spent a little bit of time coming up with something that might have been worthy of the assignment. I never did anything with it, or showed it to anyone, but I was reasonably sure that no one in that class at least would be able to figure it out. I should have put my money where my mouth was then. I might have been able to turn a profit betting people they couldn’t solve it in a given time limit. Ah well, hindsight is 20/20 as they say.

Instead, I present my code and the message it contains and invite you to work out the key. If you do figure it out, please don’t post the solution, but  I’d be really interested to hear about how you went about attacking the problem, so by all means leave a comment.

The message: the quick brown fox jumps over the lazy dog

IMPORTANT EDIT: In a moment of paranoia I double-checked my key and noted that there is a small change to the decoded message. In the coded text, ‘jumps’ is actually ‘jumped’. To those of you who have started, I apologise profusely. This means that there is an extra letter to the message than you thought you were dealing with, and rather than an ‘s’, you have a ‘d’ and an ‘e’.

The revised decoded message is:

The message: the quick brown fox jumped over the lazy dog

The coded message:
n g o c w u o y j   r
  f l l l q m v   e k
  o i y k b v   r x a
  k s e a t   d i b o
  v h a v   e u i p l

edit: James Bach has rightly pointed out that I could have worded my challenge a little more clearly.

There are an infinite number of keys that can associate your output with your input. For instance, the key might be simply to look at the first letter in the top left, and “n” means “quick brown fox…”

My intention is that people would attack this problem as though they did not know what the message was in an attempt to resolve the letters presented into the answer provided. I had a particular key in mind when I put it together, so the letters do resolve into the message given.


Okay, so a few people have asked for hints.
Here’s the deal – I’ll post a few hints, but I’m curious to know what you’ve tried and what you thought. I’ve posted one hint below. I will post more, but I’d like to know – How did you approach the problem? What strategies did you employ? What effect did the hint(s) have?

Hint 1

There are red herrings

Hint 2

There is a hint in the layout

Hint 3

Some letters are overloaded (have more than 1 meaning)

Congratulations to Rushmila Islam, who has at least worked out the message component, if not the complete cipher (which is trivial once the message is in-hand). Here’s another pangram (one with all the letters this time).

The coded message:
k e i f v a l p q u w
  b m a g n z i e c e

  m g d r w o o t a h
  y j a w u x a g e s

I kinda wish I’d put this one up first now. It looks trickier 🙂
Rushmila (or anyone else) – care to post the decoded message?

17 thoughts on “One for the puzzle nerds

  1. OK, I’ve not yet worked it out, but i thought I would share some thoughts, who know it might spark an idea.

    The things that strike me are
    1) the visual nature of the coded message. It makes me think that this is part of key? When I copied and pasted the letters into wordpad I realised its actually quite hard to get the characters aligned so smoothly. Why go to all that effort? There must be something in that.
    2) Whats with the n? why stick it out?

    Two ideas:
    The letter pattern strikes me as similar to a keypad, but no far I see no relation, so this may be a furfe
    There are some patterns in the message, e.g lots of v’s in one diagonal

    Have fun

  2. I’m contemplating adding some hints, maybe in black on black so that those that want to see them can highlight them or look at the page source. Let me know if you’re for or against this.

  3. I’ve done a bunch of things to analyze this. I still have not solved it. I need to go over it again in case I’ve made an error.

    I haven’t looked at any hints.

    – The puzzle is not an anagram (or not just an anagram), because the letters are different and one is missing.

    – The cipher is probably not static letter substitution, because the number and distribution of letters in the message don’t match that of the ciphertext. For instance in the ciphertext four letters occur three times, but no letters occurs three times in the clear text. Also, I don’t see and instance of a three-letter string repeated, which I would expect to see for the two “the’s”.

    – I have started from each corner in each direction and shifted the letters numerically (assuming a 26 letter wheel) to see what it would take to get “the.” The result doesn’t look like any meaningful pattern to me.

    – We can’t assume that the whole grid is meaningful, but FWIW, it’s a 5 by 11 grid with 9 spaces (there are also nine words in the cleartext). There are 36 letters not including spaces in the cleartext, and with spaces it’s 44. There are 46 letters in the ciphertext, so it would seem that 10 letters are filler or else this is some kind of conditionally multi-letter code.

    – It may be that part of the ciphertext is the cipher itself. Perhaps the entire top row is part of the cipher rather than the ciphertext.

    – It may be that the coordinates of the grid are part of the cipher. I looked at that, too and found no meaningful pattern.

    – It may be that the pattern of spaces is significant, or it may be irrelevant. The spaces in the cleartext may be explicitly encoded or maybe not.

    – It may be that the letters are being encoded into binary and manipulated in some fashion. I don’t see any meaningful pattern there, either, but I haven’t delved too far into that.

  4. I was just checking back to see if you left a hint, so here is what I have tried so far.

    I have been mainly focused on finding the word “the” since it is the first and also the only repeated word in the message.

    I also tried finding a pattern for the letters “o” and “e” since they are the two most occurring in the message.

    I don’t believe the cipher text has static letter substitution. As James’ also mentioned, the ciphertext doesnt match up. In the ciphertext there are 3 letters that repeat 4 times, while the mesage only has 2 letters appearing 4 times. and the total number of letters do not match up in any combination of counting with or without spaces.

    I am currently working out some different scenarios with n being a possible key or pointer to the starting point or both. Since n is the 14th letter of the alphabet I am working on using 14 and 1+4.
    – I have currently tried adding combinations of 1 and 4 to the letters in the ciphertext to look for patterns, I have also tried using 1 and 4 in different combinations to find a pointer(i.e. 1st row, 4th column). No luck there yet.

    I am also taking into account all the possibilities with the spaces in the cipertext and message, with and without counting n, with and without spaces, to look for any patterns.
    – The coded message has 46 chars including n 45 without n.
    – It has 55 total characters+whitespaces , 51 without left column of whitespaces, and 49 without the middle spaces. (also can count it without the n)

    I have also tried to work out using the position of the spaces as being values, i.e. the first row has a space in the 10th column, 9th if we don’t count n, and it leaves 1 letter in the right which could be significant or the sum of those letters could be significant.

    Those different scenarios are whats been filling several pages in my notepad+ the past few days. I am not sure if I am getting any closer but there are plenty of possibilities to explore! I will probably look at the hint tomorrow and see if it helps shed some light on any of my work so far.

    -Michael A.

  5. I’ve done some analytical calculations/statistics, eg. the entropy of the cipher text is 4.41 with a possible maximum of 4.7 whereas the entropy of the plain text is 4.44. This means, the encryption is very weak or points to an classical symmetric encryption, like Caesar, XOR, Vigenere, …

    The histograms of both texts are different, so it’s not a permutational cipher (and for that reason no Caesar).

    It seems to me that the structure is part of the code, but I have no answer yet.

  6. Congrats on the puzzle, i must admit that it caught my attention.

    What I’ve done so far:

    First I’ve taken the puzzle and wrote it on a piece of paper in a 11 x 5 table to see it better. From here I’ve easily counted that there are 55 characters from which 9 blank spaces and 46 letters. I’ve also counted the number of letters from the message – 36 letters + 8 spaces.

    Then I’ve taken the message and started counted how many times does each letter repeats itself in the message. From this I’ve seen that some letters appear fewer times in the coded message then in the plain message. So, we are not dealing with some sort of random letters which can be rearranged to obtain the initial message.

    I don’t have yet a solution but I hope that I will find it this weekend.


  7. Nice puzzle!!
    I’ve solved it at my level. I’ve analyzed the encrypted message and there was no ‘z’ and in the original message there was no ‘s’. This gave me the first clue. Then I organize the alphabet considering ‘z’ as ‘s’. Then I encrypt each word according to my formula. I wrote the whole message according to the formula and used * as a garbage character. I fill the space with garbage value. At the very first look I found ‘the’. Then I rotate the encrypted message vertically and I found the words!! Those are matched with my code. I got the pattern.


  8. Congratulations Rushmila, you have the message. I wonder if you have completely worked out the cipher, however. I’m going to post a follow-up – I’m curious as to your thoughts on what the extra letters mean. Did you use the hints provided?
    (I have removed your subsequent comments with the actual answer, btw. I’d like to leave it as-is for anyone who is late to the party and still wants to have a go.)

  9. The message for the new pangram is:
    Pack my box with five dozen liquor jugs

    There currently is no electricity in my house so will post how I figured it out after an hour or so. Thanks Ben, that was fun!

  10. Ok electricity is back 🙂

    First of all I would like to congratulate Rushmila on working so hard to figure out the previous puzzle.

    Now about how I got the new pangram. Since there was no clue what the message was this time (except that its a pangram), I figured it may be a good idea to find the letter that usually has a high frequency in a sentence. I assumed it could be ‘e’. But still did a google search and found the following helpful:

    I used MS Word to count the frequency of each letter, using the replace feature. From that it looked like ‘a’ was most frequent (i.e. showed up 5 times). So I replaced ‘a’ with ‘e’ and used the same difference for all the other characters. After looking at the replaced letters, I couldn’t make up the sentence. Then I realized that the last coded message had quite a number of dummy letters. So I tried the next most frequent letter in the pangram…

    Nice work. Your solution is correct. I’ve removed the rest of your solution in case others want to try their hand (Sorry Sebi, I was too late in your case).
    I have posted the solution over in the ‘what I learned’ post. Cheers -Ben

  11. Nice puzzle. Too bad I didn’t found it sooner, because seeing the comments from Sajjadul it looks like the solution is there.
    Its good to see more puzzles. I am searching myself for those and also try to create new ones.


  12. It was a nice puzzle to solve. I also solved the puzzle but not in the way Rushmila apu did.

    It took me hours to solve the puzzle. At first I was mislead but later on, I got the pattern. I compared the letter frequency of the puzzle and the message. In the puzzle, o, l and v occurs 4 times and in the message, e and o occurs 4 times. I compared these high frequency letters and got a mach for o (in the message) with v (in the puzzle) and tried the formula for the other letters. After decoding the puzzle, I got the original message. There are some extra letters used for spacing between words.

    Thank you for posting such an interesting puzzle.

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