Challenge 7B was a beast! The AMSCO cipher is a classic pencil and paper column transposition, with a twist. As we said in the hint the other day, you can read about it at https://cryptogram.org/cdb/aca.info/aca.and.you/chapter_09.pdf#AMSCO. It was tough, but still 281 of you cracked it which really impressed us. The solution to 7A contains a lot of intel about Challenge 8 so whether or not you tackled that last week, take a good look at the solution.
If you have enjoyed the Cipher Challenge you should definitely try the Christmas puzzles set by Robert Hannigan, the Director of GCHQ. The first one is not too tough and you should all be able to crack it, after that things get really interesting. You can find the first stage at https://www.gchq.gov.uk/press_and_media/news_and_features/Pages/Directors-Christmas-puzzle-2015.aspx
If you have any other good puzzles or wondered how to send us a Christmas Card then tweet us with your messages. We love to get them!
As usual we are providing random prizes to competitors who took part in part A this time, and each of the following 8 teams will win a cheque for £25. We will be in touch by email to the address you gave us when registering, so do please check it and get back to us promptly so we can process your award.
And for the last time this year "To everyone else, there is always next week".
Good luck,
Harry
Winners of the Part 7A Prizes:
Robin Lyster, Elizabeth Perry from Matthew Arnold School
Adil Moosa from Ealing Independent College
Kush Christie-Verma, Flynn Whittaker, Tom Patterson, David Hamer, egor kaygorodov from Danes Hill Preparatory School
Jessica Richards from South Wilts Grammar School for Girls
Esther from William Farr CofE Comprehensive School
Alan King, Michael Stevens from St Nicholas Catholic High School
Rebecca Smy, Daniel Whiteley from Plume School
Siddhant Nayak, Sankarsh Makam, Alfie Cross, Jacob Spence from Bishop Wordsworth's Grammar School