CyberFirst Puzzle

Created:  15 Jan 2018
Updated:  22 Jan 2018
We will be posting solutions to all our challenges and puzzles on Wednesday morning at 10am! Good luck!
Can you crack our CyberFirst puzzles to celebrate registration for CyberFirst Girls Competition going live?

The NCSC and several CyberFirst Girls Competition finalists from 2017 appeared on Radio 4's Today programme on Monday morning (15th January) with a challenge for the listeners.

Whilst promoting the 2018 CyberFirst Girls Competition (with registration now live!) some challenges were set. Can you solve them?


Challenge 1: ‘Rotters’

Q. Thirteen rotters stole my answer and they ROTated it by 4 and then ROTated it by 10 and all I have left is Uccr ziqy hc ozz QmpsfTwfgh Uwfzg! - can you help me get my answer back?

Explanation: Solution Rot13 is a letter substitution cipher, it’s a special case of the Caesar cipher. To obtain the answer, undo the ROT13 4 letter shift and the ROT13 10 letter shift. To get back to the original answers you need to rotate 26 letters then a=a again. 26-14 = 12. Using a ROT13 12 letter shift will return the deciphered text.  



Challenge 2: Domino Logic

  • We can use dominos to create logic gates, you just have to work out how the dominoes will fall.
  • Pushing a domino input represents a 1 on a logic gate. Leaving dominos standing represents a 0. 
  • Can you work out what would happen when you push the dominoes and use it to complete the logic tables below?


Domino logic


Challenge 3: Decode the secret message

Can you work out what the sentence says?

This gets redrah ot wvguwv kkwdfm 647 892546 848858234 8112 38313538333238373334323132383231323834313638313538343834383838333534 ...-- --... ...-- -.... ...-- ....- ...-- ---.. ...-- -.... ...-- ---.. ...-- ....- ...-- ...-- ...-- --... ...-- ...-- ...-- ....- ...-- ....- ...-- ---.. ...-- ..... ...-- ---.. ...-- ..--- ...-- ---.. ...-- ...-- ...-- ..... ...-- ....- ...-- ....- ...-- ..... ...-- ...-- ...-- ---.. ...-- .---- ...-- ---.. ...-- ---.. ...-- ....- ...-- -.... ...-- ---.. ...-- ....- ...-- ...-- ...-- ....- ...-- ---.. ...-- ..... ...-- ---.. ...-- ..---


This challenge looks quite hard to solve and in some ways it is, but with a little time and effort we can see that we are provided with clues in how to solve it in the forms of patterns. The first thing you might notice is that there are different "chunks" of the message that appear different the more of the sentence you read. From this you can start analysing the first chunk.

"This gets" - Doesn't appear to be anything meaningful, but would make sense as the start of a sentence.

"redrah ot" - Since we think this is a sentence, these are probably words - a bit of looking at it shows it should probably read "harder to", and the letters have just been reversed.

"wvguwv kkwdfm" - If this is a sentence, these are probably more words, and "this gets harder to" probably means there is a more involved method to hide the true words. A bit of analysis on the letters would show that it's probably using some kind of rotational cipher, or a lucky guess at a Caesar cipher (of 18 characters, coincidentally the year of the competition) would also provide the correct answer of "edoced sselnu". So it looks like the previous words reversal has also been applied, reverse this and we get "decode unless" which makes sense in the context of the sentence.

By this point, hopefully the pattern of two words having operations applied has been noticed.

"647 892546" - The only real clues to go on here are that they are probably words, based on information so far and their structure. Through their format you can hopefully guess they are words that have been typed on a phone keypad. Decoding this gives us a variety of options, which we need to shift by 18 and reverse as that's what has happened so far. Once shifted and reversed, there should only be two dictionary words that make sense in the context: "you worked".

"848858234 8112" - This uses ones, which aren't letters on the phone keypad. As we're getting further into the sentence, it is getting tougher, but previously words have been "rotated" using a Caesar cipher - we can try this on the numbers, and rotating up by 1 gives us something workable. Applying the previous decoding operations gives us: "somewhere like".

"38313538333238373334323132383231323834313638313538343834383838333534" - These last two are obviously encoded differently, and we were warned it would get harder so let's take them one at a time. We can try doing the same as last time, but it's not working, after a think about what else this data could be, we can try to HEX decode it, this gets us back to shifted numbers and we can decode it as we did before, but it doesn't work. What else have we seen done previously that we haven't tried? Reversing! if we reverse the numbers it makes sense and should give us "dashzerodotsevenfourtwoeightzeroseven" a bit confusing, but a bit of head scratching and we can work it out as co-ordinates!

"Morse" - the last one, it's quite obviously Morse if you've ever seen it before, and once decoded from Morse can be decoded the same, to "fiveonedotnineninesixfivethreefour". YES! where does that take us? The sea? Not quite, reverse those co-ordinates and they should point to Bletchley Park Mansion! The whole challenge when decoded should read:

"This gets harder to decode unless you worked somewhere like Bletchley Park Mansion"

Hopefully that wasn’t too hard, and you managed to solve it with a bit of perseverance and by anticipating what was next based on the information available!


Challenge 4: Anagram Crossword

We hope to inspire the next generation of cyberists, can you find some inspirational tech innovators from our clues (and solve the anagram hidden in the grey boxes)?

anagam crossword


2d,4d   - Gear chopper    - b.1906 - (5,6)

3d,5d   - Loss I hope win - b.1957 - (6,6)

7d,6a   - I capable lass  - b.1623 - (6,6)

8d,7a   - Bang ratio      - b.1949 - (5,4)

11d,9a  - A vocal Adele   - b.1815 - (3,8)

12a,1d  - Herald army     - b.1914 - (4,6)

13a,10a - Lunar giant     - b.1912 - (4,6)


Challenge 5: Can you crack the NCSC’s regex crossword?

regex crossword


Can you crack our cryptic crossword? Instead of a word or phrase, each clue is a regular expression (or a ‘regex’). To complete the puzzle, find the letter matching both the horizontal and vertical regex for each square.

Confused? Here are a few pointers to get you started:

  • Characters in square brackets [SUCHASTHIS] are 'character classes'. They signify any of the characters in the box.
  • A caret/hat (^) inside a character class [^LIKETHIS] inverts the match. (Must NOT be any of the characters in the box).
  • Numbers in curly brackets (like {2}) means that the character/pattern immediately before it must occur this number of times. (So A{3} literally means AAA).


CyberFirst Girls Competition 2018 - NOW OPEN

Calling all schools! We are searching for the UK’s most cyber-savvy 12-13 year olds to compete in fun online cyber security challenges. If you are interested in taking part in this year's CyberFirst Girls Competition then head to

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