C839 Introduction to Cryptography| 247 QUESTIONS| WITH COMPLETE SOLUTIONS

Cryptography CORRECT ANSWERS: The science of altering communication so that it cannot be understood without having the key. cipher CORRECT ANSWERS: The algorithm(s) needed to encrypt and decrypt a message. Mono-alphabet substitution CORRECT ANSWERS: Substitute one character of cipher text for each character of plain text. Caesar cipher CORRECT ANSWERS: Every letter is shifted a fixed number of spaces to the left or the right in the alphabet. Ciphertext CORRECT ANSWERS: The resultant text after being subjected to the algorithm and key. Atbash Cipher CORRECT ANSWERS: Reverses the alphabet ( A becomes Z, B becomes Y ... ) - Mono-Alphabet Substitution Cipher. Hebrew code. Affine Cipher CORRECT ANSWERS: single substitution cipher. Each letter is mapped to a numerical value, permuted with a math function and then converted back to a letter. Affine cipher formula CORRECT ANSWERS: ax + b (mod M) ROT13 CORRECT ANSWERS: One type of substitution cipher in which the entire alphabet is rotated 13 characters. Scytale CORRECT ANSWERS: Physical cylinder used to encrypt messages. Turning the cylinder produced different ciphers. Single substitution weaknesses CORRECT ANSWERS: Preserve the underlying letter and word frequency. A low-end PC is more than enough to brute force crack a single sub cipher. Multi-Alphabet Substitution CORRECT ANSWERS: Rotates through various keys. Cipher disk CORRECT ANSWERS: a physical device used to encrypt. Invented by Leon Alberti in 1466. The cipher disk was polyalphabetic; each time you turned the disk, you used a new cipher. Vignere cipher CORRECT ANSWERS: Invented in 1553 by Giovan Battista Bellaso. A method of encrypting text by applying a series of different mono-alphabet ciphers based on the letters of a keyword. Playfair Cipher CORRECT ANSWERS: Invented by Charles Wheatstone in mid 1