Ciphers Flashcards
Define caesar cipher:
A substitution cipher where one character of plaintext is switched for another
Define vernam cipher:
A method of encryption that uses a one-time key (pad) to create ciphertext that is mathematically impossible to decrypt without the key
Define transposition cipher:
A method of encryption where the letters are rearranged to form an anagram
Define polyalphabetic:
More than one alphabet
Define frequency analysis:
The study of how often words, letters and phrases are used
Define railfence cipher:
Where the plaintext is split over several lines in a diagonal pattern
Define route cipher:
Where the plaintext is put into a grid
How to use the vernam cipher:
A random key is created, the Baudot representation/Unicode/ASCII is identified (5 binary digits), the key and plaintext characters are each XOR-ed, the new corresponding Baudot representation is identified and that’s the new character
Define Baudot code:
A five digit character code that predates ASCII
Define one-time pad:
A key that is only used once and then discarded
What makes the vernam cipher so secure:
Random key, used once, secret
Issues with vernam cipher:
Hard to get a random key, hard to keep it secret, no way to authenticate sender
