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Cipher facts
Terms and definitions
Math
100

This Polish mathematician first broke Enigma.

Who is Marian Rejewski?

100

This is the Caesar decryption of IRXU using the key a-D.

What is "four"?

100

This code (which is not a cipher) uses two symbols to represent letters and numbers, originally for use in telegraphs.

What is Morse code?

100

A prime integer has this many positive factors.

What is two?

100

This is the value of 4!.

What is 24?

200

This cipher was invented by Charles Wheatstone, but was not named after him.

What is Playfair?

200

This is the monoalph decryption of OFUE using the keyword TASTE.

What is "nerd"?

200

A monoalphabetic substitution cipher has this many possible keys.

What is 26! keys?

200

This term is used to describe the interchanging (or moving) of symbols in a cipher.

What is transposition?

200

This is the number of ways to select two objects from a pool of 5 and put them in order (number, not formula).

What is 20?

300

This British mathematician was tasked with mechanizing the breaking of Enigma at Bletchley Park.

Who is Alan Turing?

300

This is the Vigenere decryption of GOCS using the keyword NO.

What is "tape"?

300

A Kasiski examination is used to determine this.

What is the length of a Vigenere keyword?

300

This term refers to a descending product of positive integers that are less than a certain number.

What is a factorial?

300

This is the minimum number of moves required to solve a 3-disk Tower of Hanoi puzzle.

What is 7?

400

Independently of Kasiski, this person discovered a general attack on the Vigenere cipher.

Who is Charles Babbage?

400

This is the Playfair decryption of HC PQ using the keyword LURKS.

What is "crop"?

400

In the ADFGVX cipher, the key grid holds this many symbols.

What is 36?

400

This term means a piece of known or suspected plaintext.

What is a crib?

400

This is the prime factorization of 20.

What is 2*2*5?

500

Military officials from this country first broke the ADFGVX cipher, although they did not have a general method for doing so.

What is France?

500

This is the Enigma decryption of NUL with rotor setting 123 AAA and no plugboard.

What is "ace"?

500

In the Playfair cipher, each plaintext letter can only encrypt to this many other letters.

What is five?

500

This term is used to refer to a pair of letters.

What is a digraph?

500

This is the number of ways to select a group of 3 objects from a pool of 5 (number, not formula).

What is 10?

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