Harry
@cipher-challenge.bsky.social
Join Harry at the National Cipher Challenge, which invites school-aged participants to put their code-breaking skills to the test every Autumn. Created by the School of Mathematical Sciences @UniSouthampton.
We are looking forward to the launch of the official competition challenges at cipherchallenge.org at 3pm this afternoon. If you want to find out why the three Charles (Babbage, Dickens and Wheatstone) need to talk to the US president, there is only one way to find out!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
November 6, 2025 at 11:54 AM
We are looking forward to the launch of the official competition challenges at cipherchallenge.org at 3pm this afternoon. If you want to find out why the three Charles (Babbage, Dickens and Wheatstone) need to talk to the US president, there is only one way to find out!
Just like last year we broke the records for Challenge 2 entries with nearly 8100 of you signed up to take part. Practice Challenge 3 starts at 3pm today, so if you haven't signed up yet head over to cipherchallenge.org to get involved
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
October 23, 2025 at 10:47 AM
Just like last year we broke the records for Challenge 2 entries with nearly 8100 of you signed up to take part. Practice Challenge 3 starts at 3pm today, so if you haven't signed up yet head over to cipherchallenge.org to get involved
The clock is ticking down to the 3pm start of Practice Challenge 2 at cipherchallenge.org! We had over 7000 registered for the first round and there is still time to register for the competition. Hope to see you there!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
October 16, 2025 at 1:21 PM
The clock is ticking down to the 3pm start of Practice Challenge 2 at cipherchallenge.org! We had over 7000 registered for the first round and there is still time to register for the competition. Hope to see you there!
We couldn't be happier with the response to the first cipher challenge this year. Over 7400 signed up already and we're still on the 1st practice challenge! Head over to www.cipherchallenge.org/ to to get your students signed up in time for the 2nd practice challenge tomorrow.
October 15, 2025 at 8:05 PM
We couldn't be happier with the response to the first cipher challenge this year. Over 7400 signed up already and we're still on the 1st practice challenge! Head over to www.cipherchallenge.org/ to to get your students signed up in time for the 2nd practice challenge tomorrow.
Over 5000 already registered at www.cipherchallenge.org ready for the practice challenges to start tomorrow at 3pm. If you are aged 11-18 and want to learn codebreaking and show the world what you can do then head over and sign up!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 8, 2025 at 10:39 AM
Over 5000 already registered at www.cipherchallenge.org ready for the practice challenges to start tomorrow at 3pm. If you are aged 11-18 and want to learn codebreaking and show the world what you can do then head over and sign up!
The 24th National Cipher Challenge is now open for registrations and we have already had 1200 sign ups. The competition starts on October 9th, so there is time to register your teams and get them investigating codes and ciphers. Catch up on our news at www.cipherchallenge.org.
September 22, 2025 at 10:44 AM
The 24th National Cipher Challenge is now open for registrations and we have already had 1200 sign ups. The competition starts on October 9th, so there is time to register your teams and get them investigating codes and ciphers. Catch up on our news at www.cipherchallenge.org.
Day 1 and we have reached our first 500 registrations at www.cipherchallenge.org already! Will we beat last year's record 9,000? That is up to you!
September 18, 2025 at 6:10 PM
Day 1 and we have reached our first 500 registrations at www.cipherchallenge.org already! Will we beat last year's record 9,000? That is up to you!
Ready to register for the National Cipher Challenge? The site opens tomorrow. Did you know that as a teacher you can monitor the teams at your school? You will be able to read more about that at www.cipherchallenge.org/how-to-bulk-...
September 17, 2025 at 8:16 AM
Ready to register for the National Cipher Challenge? The site opens tomorrow. Did you know that as a teacher you can monitor the teams at your school? You will be able to read more about that at www.cipherchallenge.org/how-to-bulk-...
Just a few days now until the 2025 National Cipher Challenge opens for registration! If you know someone aged 11-18 who might like codes and ciphers (or who might not yet know that they do!) then get them to take a look at www.cipherchallenge.org on Thursday.
Registration opens 18th September 2025. Competition starts 9th October 2025.
www.cipherchallenge.org
September 15, 2025 at 9:40 AM
Just a few days now until the 2025 National Cipher Challenge opens for registration! If you know someone aged 11-18 who might like codes and ciphers (or who might not yet know that they do!) then get them to take a look at www.cipherchallenge.org on Thursday.
We are looking for additional content to add to our Community page. You can read last year's at 2024.cipherchallenge.org/boss-your-ci...
If you took part and would like to feature on this year's site, then do get in touch either here or by email at [email protected]. We would love to hear from you!
If you took part and would like to feature on this year's site, then do get in touch either here or by email at [email protected]. We would love to hear from you!
Meet some of the Cipher Challenge community ... - National Cipher Challenge 2024
Your stories about taking part in the competition.
2024.cipherchallenge.org
September 12, 2025 at 11:24 AM
We are looking for additional content to add to our Community page. You can read last year's at 2024.cipherchallenge.org/boss-your-ci...
If you took part and would like to feature on this year's site, then do get in touch either here or by email at [email protected]. We would love to hear from you!
If you took part and would like to feature on this year's site, then do get in touch either here or by email at [email protected]. We would love to hear from you!
Posters for this years www.cipherchallenge.org should be arriving in schools this week. If you want to help promote the competition, why not post a picture of the poster on your boards?
Registration opens 18th September 2025. Competition starts 9th October 2025.
www.cipherchallenge.org
September 8, 2025 at 8:48 AM
Posters for this years www.cipherchallenge.org should be arriving in schools this week. If you want to help promote the competition, why not post a picture of the poster on your boards?
Holding a Clubs/Societies/Enrichment Fair for your school or college? The National Cipher Challenge might be just what you need. Here is a poster you can use to promote it! The site will open for registration on Sept 18th and the competition starts Oct 9th. Challenges weekly throughout term!
September 2, 2025 at 11:37 AM
Holding a Clubs/Societies/Enrichment Fair for your school or college? The National Cipher Challenge might be just what you need. Here is a poster you can use to promote it! The site will open for registration on Sept 18th and the competition starts Oct 9th. Challenges weekly throughout term!
Want something to read on these idle summer days? You could take a look at this short article by one of our cipher challenge competitors: mathsrant.com/2025/07/28/t...
(Not that the Elves at CC HQ are idle. Far from it - too much to be done in prep for the new adventure. More soon!
(Not that the Elves at CC HQ are idle. Far from it - too much to be done in prep for the new adventure. More soon!
The National Cipher Challenge – More Than Just Codebreaking
I’ve been meaning to write about how I got into codebreaking — so here’s the start of a small series on maths, ciphers, and curiosity. A lot of experiences have shaped the curious, questioning pers…
mathsrant.com
August 12, 2025 at 4:24 PM
Want something to read on these idle summer days? You could take a look at this short article by one of our cipher challenge competitors: mathsrant.com/2025/07/28/t...
(Not that the Elves at CC HQ are idle. Far from it - too much to be done in prep for the new adventure. More soon!
(Not that the Elves at CC HQ are idle. Far from it - too much to be done in prep for the new adventure. More soon!
Just a heads up that now the challenge is finished we are working on the leaderboards, prizes and invitations to the National Cipher Challenge event @bletchleypark. Please do keep an eye out for messages from us on the site, and log in regularly to see if we have left one for you in your account!
January 11, 2025 at 2:33 PM
Just a heads up that now the challenge is finished we are working on the leaderboards, prizes and invitations to the National Cipher Challenge event @bletchleypark. Please do keep an eye out for messages from us on the site, and log in regularly to see if we have left one for you in your account!
We are well underway with the competition at www.cipherchallenge.org, though it is not too late to get involved if you fancy it. You'll be joining over 8500 other participants & there are still 6 challenges to break over the next few weeks. The next one goes live at 3pm today. Hope to see you there.
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
November 14, 2024 at 10:04 AM
We are well underway with the competition at www.cipherchallenge.org, though it is not too late to get involved if you fancy it. You'll be joining over 8500 other participants & there are still 6 challenges to break over the next few weeks. The next one goes live at 3pm today. Hope to see you there.
Over 8,000 signed up ready to take part in the competition at cipherchallenge.org this year! The first competition challenge runs until next Wednesday, so it is not too late to join in. Hope to see you there!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
November 7, 2024 at 7:54 PM
Over 8,000 signed up ready to take part in the competition at cipherchallenge.org this year! The first competition challenge runs until next Wednesday, so it is not too late to join in. Hope to see you there!
We have over 8,000 subscribers for the first time ever.They are all beavering away at cipherchallenge.org and putting a LOT of pressure on the marking system. If you get errors submitting, then it may be worth waiting. It won't affect your marks and will give the chips a chance to cool down!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
October 24, 2024 at 2:57 PM
We have over 8,000 subscribers for the first time ever.They are all beavering away at cipherchallenge.org and putting a LOT of pressure on the marking system. If you get errors submitting, then it may be worth waiting. It won't affect your marks and will give the chips a chance to cool down!
Tantalisingly close to 8,000 users registered at www.cipherchallenge.org with just over 24 hours to go til we publish the final practice challenge. Competition challenges start on November 7th, so if you want to join the fun head over to cipherchallenge.org and sign up! Teams or individuals welcome.
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 23, 2024 at 1:39 PM
Tantalisingly close to 8,000 users registered at www.cipherchallenge.org with just over 24 hours to go til we publish the final practice challenge. Competition challenges start on November 7th, so if you want to join the fun head over to cipherchallenge.org and sign up! Teams or individuals welcome.
Half way through Challenge 2 in this year's National Cipher Challenge and we already have over 7,800 participants. Will we break 8000? It's possible, the first 3 challenges are for practice and we usually get a bunch more signing up at the 4th round. Head over to www.cipherchallenge.org to see why!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 21, 2024 at 2:45 PM
Half way through Challenge 2 in this year's National Cipher Challenge and we already have over 7,800 participants. Will we break 8000? It's possible, the first 3 challenges are for practice and we usually get a bunch more signing up at the 4th round. Head over to www.cipherchallenge.org to see why!
Challenge 2 is live and we look forward to seeing what you make of it. These are still practice rounds, so we're trying to make them accessible to complete newbies. If you have more experience then avoid using the support we put in place at cipherchallenge.org and see how fast you can break it.
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
October 17, 2024 at 2:04 PM
Challenge 2 is live and we look forward to seeing what you make of it. These are still practice rounds, so we're trying to make them accessible to complete newbies. If you have more experience then avoid using the support we put in place at cipherchallenge.org and see how fast you can break it.
Challenge 1 is now complete and the leaderboard will be published at 11am this morning. If you can't wait to see how you did then log in at www.cipherchallenge.org and download your certificates for part A and part B to find out. And don't forget, Challenge 2 goes live at 3pm this afternoon
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 17, 2024 at 7:42 AM
Challenge 1 is now complete and the leaderboard will be published at 11am this morning. If you can't wait to see how you did then log in at www.cipherchallenge.org and download your certificates for part A and part B to find out. And don't forget, Challenge 2 goes live at 3pm this afternoon
Last day to submit entries to Challenge 1 at www.cipherchallenge.org. If you don't make the deadline 11pm tonight the next practice round goes live tomorrow at 3pm. If you miss that there's still time to register & compete in the other rounds, with prizes based on your scores in rounds 4-10.
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 16, 2024 at 10:58 AM
Last day to submit entries to Challenge 1 at www.cipherchallenge.org. If you don't make the deadline 11pm tonight the next practice round goes live tomorrow at 3pm. If you miss that there's still time to register & compete in the other rounds, with prizes based on your scores in rounds 4-10.
A couple of days left to tackle the first practice challenge at www.cipherchallenge.org, but even if you can't join us yet there is plenty of time to get ready for the main competition challenges starting on Nov 7th. All are welcome!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
www.cipherchallenge.org
October 14, 2024 at 3:52 PM
A couple of days left to tackle the first practice challenge at www.cipherchallenge.org, but even if you can't join us yet there is plenty of time to get ready for the main competition challenges starting on Nov 7th. All are welcome!
At the end of round 1 last year we had 5800 competitors signed up. Here we are on day two with over 6500 already taking part in the competition at cipherchallenge.org. If you want to see why, head over and take a look. There's still time to join in!
National Cipher Challenge
An annual codebreaking competition for UK schools and homeschooled students run by the School of Mathematical Sciences at the University of Southampton
cipherchallenge.org
October 11, 2024 at 12:52 PM
At the end of round 1 last year we had 5800 competitors signed up. Here we are on day two with over 6500 already taking part in the competition at cipherchallenge.org. If you want to see why, head over and take a look. There's still time to join in!
The team at www.cipherchallenge.org love exponentials!
October 11, 2024 at 8:36 AM
The team at www.cipherchallenge.org love exponentials!