The National Cipher Challenge is an annual

cryptographic Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...

competition organised by the

University of Southampton , mottoeng = The Heights Yield to Endeavour , type = Public research university , established = 1862 – Hartley Institution1902 – Hartley University College1913 – Southampton University Coll ...

School of Mathematics. Competitors attempt to break

cryptograms A cryptogram is a type of puzzle that consists of a short piece of encrypted text. Generally the cipher used to encrypt the text is simple enough that the cryptogram can be solved by hand. Substitution ciphers where each letter is replaced by ...

published on the competition website. In the 2017, more than 7,500 students took part in the competition. Participants must be in full-time school level education in order to qualify for prizes.

Format

The competition is organised into eight to ten challenges, which are further subdivided into parts A and B. The part A challenge consists of a comparatively simpler cryptogram, and usually provides some useful information to assist in the solving of part B. Part B is usually more complex. In later challenges the cryptograms become harder to break. In the past, part A cryptograms have been encrypted with the Caesar cipher, the

Affine cipher The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that eac ...

, the Keyword cipher, the

Transposition cipher In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters (''transposition'') without changing the characters themselves. Transposition ciphers reorder units of plaintext (typically characters or ...

, the

Vigenère cipher The Vigenère cipher () is a method of encryption, encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic cipher, polyalphabetic substitution. First desc ...

and the 2x2

Hill cipher In classical cryptography, the Hill cipher is a polygraphic substitution cipher based on linear algebra. Invented by Lester S. Hill in 1929, it was the first polygraphic cipher in which it was practical (though barely) to operate on more than t ...

. The part B challenges are intended to be harder. These begin with relatively simple

substitution ciphers In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units" may be single letters (the most common), pairs of letters, tri ...

, including the Bacon cipher and

Polybius square The Polybius square, also known as the Polybius checkerboard, is a device invented by the ancient Greeks Cleoxenus and Democleitus, and made famous by the historian and scholar Polybius. The device is used for fractionating plaintext characters s ...

, before moving on to

transposition cipher In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters (''transposition'') without changing the characters themselves. Transposition ciphers reorder units of plaintext (typically characters or ...

Playfair cipher The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of ...

s and polyalphabetic ciphers such as the

, the Autokey cipher and the

Alberti cipher The Alberti Cipher, created in 1467 by Italian architect Leon Battista Alberti, was one of the first polyalphabetic ciphers. In the opening pages of his treatise ' he explained how his conversation with the papal secretary Leonardo Dati about a re ...

. In the later stages of the competition, the

ADFGVX cipher In cryptography, the ADFGVX cipher was a manually applied field cipher used by the Imperial German Army during World War I. It was used to transmit messages secretly using wireless telegraphy. ADFGVX was in fact an extension of an earlier cipher ca ...

, the Solitaire cipher, the Double Playfair cipher, the

, the

Book cipher A book cipher, or Ottendorf cipher, is a cipher in which the key is some aspect of a book or other piece of text. Books, being common and widely available in modern times, are more convenient for this use than objects made specifically for crypto ...

and versions of the

Enigma Enigma may refer to: *Riddle, someone or something that is mysterious or puzzling Biology *ENIGMA, a class of gene in the LIM domain Computing and technology * Enigma (company), a New York-based data-technology startup * Enigma machine, a family ...

and

Fialka In cryptography, Fialka (M-125) is the name of a Cold War-era Soviet cipher machine. A rotor machine, the device uses 10 rotors, each with 30 contacts along with mechanical pins to control stepping. It also makes use of a punched card mechanism ...

cipher machines have all been used. The 2009 challenge ended with a Jefferson Disk cipher, the 2012 challenge ended with the ADFGVX Cipher, the 2014 with the

Playfair Cipher The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of ...

, and the most recent challenge ended with a sectioned Cadenus transposition.

Prizes

£25 cash prizes are awarded to eight random entrants who submit a correct solution for each part A of the challenge. Leaderboards for the part B challenges are also compiled, based on how accurate solutions are and how quickly the entrant broke the cipher. Prizes are awarded to the top three entrants at the end of the challenge. In the 2009/10 challenge, the sponsors provided several prizes: IBM provided iPod Touches to each member of the team winning the Team Prize, Trinity College provided a cash prize of £700, and GCHQ provided a cash prize of £1000. In previous years prizes such as an IBM Thinkpad laptop have been awarded. After the challenge the winners of the top prizes and other randomly selected entrants are invited to a day held at

Bletchley Park Bletchley Park is an English country house and estate in Bletchley, Milton Keynes ( Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...

consisting of lectures (with subjects such as the Semantic Web,

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

cryptography and

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as ana ...

) and the prize-giving ceremony. Current sponsors of the competition include

GCHQ Government Communications Headquarters, commonly known as GCHQ, is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the Unit ...

, IBM,

British Computer Society Sir Maurice Wilkes served as the first President of BCS in 1957 BCS, The Chartered Institute for IT, known as the British Computer Society until 2009, is a professional body and a learned society that represents those working in infor ...

Trinity College, Cambridge Trinity College is a constituent college of the University of Cambridge. Founded in 1546 by Henry VIII, King Henry VIII, Trinity is one of the largest Cambridge colleges, with the largest financial endowment of any college at either Cambridge ...

Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press A university press is an academic publishing hou ...

Winton Capital Management Winton Group, Ltd (which includes Winton Capital Management) is a British investment management firm founded by David Harding. In the United States, Winton is registered with the Securities and Exchange Commission as an investment advisor and with ...

and

EPSRC The Engineering and Physical Sciences Research Council (EPSRC) is a British Research Council that provides government funding for grants to undertake research and postgraduate degrees in engineering and the physical sciences, mainly to univers ...

References

External links

The official challenge website

The website of the 2016/17 challenge
(slightly broken)
The website of the 2015/16 challenge
The websites for the challenges earlier than this are no longer available. {{Mathematics in the United Kingdom Cryptography contests Mathematics education in the United Kingdom Secondary schools in the United Kingdom University of Southampton