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Could a 145 year old diary really destabilise our fragile peace with Russia? What does it contain that could be so dangerous? Who wrote it, and why and how was it encrypted? Jodie needs the answers and she needs them fast. Join her as she and Harry try to unravel the mystery of The KOMPROMAT FILES


Cutting Edge Cracking

Some of the winners from the 2016 competition kindly wrote up how they tackled the final challenge that year. If you are wondering what it takes to decipher a message encrypted with a brand new code then this might give you some idea. The challenges in the early rounds of the of this year’s competition won’t be anything like as difficult, but as for the later ones … Read more

A beginner's guide to code breaking

A free guide to get you started

Rules of engagement

While we try to keep things simple and friendly, the competition has some rules and you should probably know about them. We think they are clear, and they are certainly tested by time, but if you have any questions about them do contact us and we will try to get back to you within 24 hours. In the meantime you can read them here. Read more

Programming for Cryptologists

National Cipher Challenge alumnus Julian Bhardwaj wrote a rough guide to computer programming for code breakers which he has kindly allowed us to post here for you. You don’t need to be a world class programmer to do well in the challenge, you can get a long way with a word processor, a spreadsheet and some cunning, but it really helps to automate the routine jobs, and these notes will get you started.
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Congratulations to everyone who has made it this far …

Three challenges to go (8,9 and 10) and we still have loads of you on board. So far you have cracked Caesar shifts, substitution ciphers, some with little twists, and some devious transposition ciphers. Who knows what Douglas and Jodie have in store next! Challenge 8 is the last challenge with a Friday night deadline

Read on ...