A special National Cipher Challenge for extraordinary times › Forums › Bureau of Security and Signals Intelligence Forum › Ciphers and Puzzles from Competitors
31st March 2020 at 5:10 pm #45711
Let’s start a thread for competitors’ ciphers.
[Good idea, here are the rules:
If you want to set a puzzle or quiz question post it together with the answer putting the answer in square brackets with ANSWER PLEASE DO NOT POST THIS BIT at the start. For example:
What is 2+2
[ANSWER PLEASE DO NOT POST THIS BIT
(I know this is not a good puzzle, OR a good quiz question, but what do you expect?)
We will start easy (maybe not that easy) and work up as the competition goes on so that everyone has a good chance to solve your challenges.
Same idea for ciphers. If you would like to challenge the gang post the challenge together with the decrypt and a quick description of how it was encrypted. We might not post those, especially at the start, but we will certainly look at them.
Harry]1st April 2020 at 1:01 pm #45886Inactive
Harry, no matter there difficulty it may be better to put some up on day one as fillers during the ‘easy’ NCC challenges, there may be less time for them in the later stages. What do think?1st April 2020 at 1:02 pm #45901
I think that is an excellent idea, and in fact we may have a really nice surprise in a couple of days. In the meantime we will publish competitor challenges as long as they are submitted in the format I suggested above [Hint, hint]
Harry1st April 2020 at 3:08 pm #45950Inactive
@Harry Sorry about the double posting
[I didn’t see the second post,The-Letter-Wriggler are you sure there was one? Harry]1st April 2020 at 3:40 pm #45722Inactive
WILL YOU BE THE FIRST TO SOLVE THIS?
TITLE – TLW CIPHER:
Yet To Solve ThiS One
eVery LIne Will EacH
ONLy BE a LittLE Twisted
All posts to go below and kept in this thread please.
When you have solved it choose any 6 non consecutive letters from the plaintext, retain their order from left to right, and post them without spaces as your answer.
Do not use the same 6 letters as other posts.
Your post to look like this: TLW Answer: ABCDEF
The first competitor to post the CORRECT answer gets all the glory.
Of course all other correct posts will be deemed very worthy too.1st April 2020 at 3:41 pm #45968
The-Letter_Wriggler’s puzzle above is impossible, but very clever! Don’t worry if you can’t get it, there will be easier ones coming soon from a special guest!
Harry1st April 2020 at 4:39 pm #45991
No, not impossible.
TLW: OLTEET1st April 2020 at 4:40 pm #45996
I might have to put you guys on a separate site!1st April 2020 at 5:02 pm #46005Inactive
Before I could comment you Harry, Madness does it for me.
So Madness of course gets all the GLORY as I expected he would!
That was one fast solve my friend.
I now await all the worthy contestants.2nd April 2020 at 1:41 pm #46392Inactive
Harry is there a way of keeping this thread at the top of the forum?
It will go out of sight without any posts being made.
Think — Out of Sight – Out of Mind —2nd April 2020 at 1:42 pm #46395
Harry3rd April 2020 at 11:25 am #46598
Today’s episode is brought to you by the number 7197738.
This is actually an encoding rather than a cipher. It was inspired by an on-line challenge at
I took their algorithm and reduced to to only use the letters A-Z. Here is the Python code that I used to encode the “ciphertext”. Because indentation is important in Python, and because the forum server removes spaces from the beginning of every line, you should replace every occurrence of “[INDENT]” with 8 spaces (or a tab) in the following code before you use it.
from random import randint
alphabet = “ABCDEFGHIJKLMNOPQRSTUVWXYZ”
[INDENT]numbers = 
[INDENT]for char in p.upper():
[INDENT]while len(numbers) > 1:
[INDENT][INDENT]n = randint(0,len(numbers)-2)
[INDENT][INDENT]x = numbers[n]
[INDENT][INDENT]y = numbers[n+1]
[INDENT][INDENT]if x > y:
[INDENT][INDENT][INDENT]z = x*x + x + y
[INDENT][INDENT][INDENT]z = y*y + x
[INDENT][INDENT]numbers = numbers[:n] + [z] + numbers[n+2:]
Here is the “ciphertext”:
If you enjoy this sort of thing, I have another one ready, called the “factorization cipher”. Yes, I stole it too from somewhere else.
[I should note that I had to do a bit of tinkering to make the code run – mostly because some of the characters rendered on the website are not recognised by Python. Try retyping offending lines if you can’t tell what the problem is! Also, nice job on [INDENT] being exactly eight characters.
water_biscuit]3rd April 2020 at 12:07 pm #46690Inactive
Should EACH [INDENT] be only 4 spaces? I get error with 8. (using Thonney)
If using paste the quote marks will need to be replaced as they are ‘web’ quotes.3rd April 2020 at 3:55 pm #46761
Each [INDENT] should be exactly the same as every other [INDENT].
I don’t know who Thonney is, but you should kick him to the curb.
The corruption of ‘ and ” is due to the server. It does that to everything.3rd April 2020 at 5:36 pm #46792Inactive
@Madness Hi there 🙂
Thonney is simply a windows based interface to run the standard and current up to date python, it has nothing to do with the actual programming of python.
I was simply asking not stating about the indentation. I replaced each [INDENT] with 4 spaces and it looks and works fine.
You know from my emails to you that I have just started to learn the python instruction set as I program in Pascal, I am not new to programming.
Agree with the corruption statement, I was just pointing it out for others.
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