Paying homage to our fondness of brain-teasers, every month we post a new challenge created by the Forensic Technology team, focusing on logical, analytical and coding problems.

For this month’s challenge you need to put your spy hat on and decrypt a message.

The first step is to revisit the Challenge #1 blog. Shameless, we know.

Using the answer to the number of prime numbers that have digits that sum to 13, can you find the key word in the post? (Clue: we have decided that two or more words that are hyphenated should only be counted as one).

Found it? Great! The encrypted message is below, with a handy matrix that can be used to crack the code (and give you inspiration)! You will need to use the key word to decipher the original meaning.

We hope you ‘Blaise’ through the rest of this challenge!

Hint: Capitals are important and should be preserved.

Once you have the decrypted message, the dots and dashes can help you reach the final goal.


If you crack the code, then post the first letter of each word in the title of what you find in the comments below.

We’ll be posting the solution next month, along with Challenge #3.


What's the answer?

i) Using the answer from the first puzzle (i.e. 141 primes) you needed to find the 141st word in the puzzle, which was ‘tactic’. Remember to count hyphenated words as one.

ii) Our message can then be decrypted using ‘tactic’ as the keyword in a Vigenère cipher. The keyword is repeated to match the length of the encryption excluding any numbers (see final decryption matrix in iii)). For instance, in the recta tabla below we use the column that corresponds to the first letter of the keyword, i.e. the ‘t’ column, to decrypt the first letter ‘r’ of the encryption. We can see that the letter ‘r’ in this column is in the ‘y’ row. Thus the first letter of the message is ‘y’. It’s important to preserve capitalisation as will be shown later.




iii) Repeating this process for each encrypted letter and the corresponding letter in the key gives the below message.



iv) Finally, with a bit more thought, you will arrive at the link youtu.be/N5vJSNXPEwA for you to enjoy! 

Check out September's Paralympics themed challenge here.

If you are someone who enjoys problem-solving, logical thinking and technology, check out our Forensic Technology graduate programme roles to see if they are the right fit.



  • I'll just put "CYS" here so that others can do the next initials!

    Posted by: Ross Johnstone on 10/08/2016


    Loved it - very imaginatively done and I've always enjoyed cryptography. Didn't even need to look up the hint :D

    Posted by: Daniel on 15/08/2016

  • Would have responded earlier but only just got back from camping yesterday :D

    Posted by: Daniel on 15/08/2016

  • Well solved both, we are glad you enjoyed it!

    Posted by: Josh (Deloitte) on 17/08/2016

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Comments are moderated, and will not appear until the author has approved them.