Module 1- History of Cryptography

Question 1

Science of altering communication so that it cannot be understood without a key

Answer 1

Cryptography

Question 2

Algorithms that simply substitute one character of cipher text for one character of plain text

Answer 2

Mono-Alphabet Substitution Cipher

Question 3

Every letter is simply shifted a fixed number of places to the left or to the right

Answer 3

Caesar Cipher

Question 4

Hebrew cipher which substitutes the first letter of the alphabet for the last, and the second letter for the second-to-last, in other words, it simply reverses the alphabet.

Answer 4

Atbash Cipher

Question 5

Any single substitution alphabet ciphers where each letter in the alphabet is mapped to some numeric value, permuted with some relatively simple mathematical function, and then converted back to a letter.

Answer 5

Affine Cipher

Question 6

A single alphabet substitution cipher where all characters are rotated 13 characters through the alphabet.

Answer 6

ROT13 Cipher

Question 7

Physical cylinder that was used to encrypt messages. Turning the cylinder produced different ciphertexts. Required a cylinder of the same diameter as the cylinder used to create the message to read the message.

Answer 7

Scytale Cipher

Question 8

Single substitution weaknesses

Answer 8

Literacy rates

Letter frequencies

Question 9

Examples of Multi-Alphabet Substitution

Answer 9

Cipher Disk

Vigenere Cipher

Question 10

Invented by Leon Alberti in 1466, physical device, each turn of the disk produces a new cipher

Answer 10

Cipher Disk

Question 11

Once considered very secure, invented by Giovan Battista Bellaso in 1553. Used until early 1900’s. Encrypts text by using a series of different Caesar cipher based on a keyword.

Answer 11

Vigenere (vee-ja-nare) Cipher

Question 12

First-person to carry out a successful attack on a Vigenere cipher

Answer 12

Friedrich Kasiski

Question 13

Invented by Charles Wheatstone in 1854. Encrypts two letters instead of one, this makes it more complex. Uses a 5x5 table containing a keyword. No more secure than any other older ciphers.

Answer 13

Playfair Cipher

Question 14

A transposition cipher invented 1918 by Fritz Nebel, used a 36 letter alphabet and a modified Polybius square with a single columnar transposition

Answer 14

ADFVGX Cipher

Question 15

Early attempt to make substitution ciphers more robust, masks letter frequencies, plain text letters map to multiple cipher text symbols

Answer 15

Homophonic Substitution

Question 16

Message hidden in unrelated text. Sender and receiver have pre-arranged to use a pattern to remove certain letters from the message which leaves only the true message behind

Answer 16

Null Ciphers

Question 17

Sender and receiver agree on a particular book, coordinates are then used to locate words of an intended message in the book

Answer 17

Book Ciphers

Question 18

Most widely known transposition cipher, encrypts the message by altering each letter on a different row, message must then be written down left to right and put into rows

Answer 18

Rail Fence Cipher

Question 19

Electromechanical rotor-based cipher used in World War II

Answer 19

Enigma Machine

Question 20

Free tool that allows you to enter text and then choose a historical algorithm to encrypt the text

Answer 20

CrypTool