It will be a written quiz taking the whole period. It will be closed-book. I will provide such things as the Vigenere square, multiplication table mod 26, english letter frequencies, and alphabet-to-number table, if needed.

Topics:

Use the Cryptosystem organizer to study the following cryptosystems (so this means being able to describe things like key space, how to encrypt/decrypt, being able to apply various cryptanalysis techniques). I may ask you to encrypt, decrypt, or cryptanalyse.

Caesar cipher

Scytale (no need for any cryptanalysis techniques beyond exhaustive search, but do know the system)

Substitution cipher (alphabetic substitution)

Vigenere cipher

Affine cipher

Hill cipher

You should be adept at:

modular arithmetic

the notion of invertible element in modular arithmetic, finding inverses by inspection

the notion of an invertible matrix in modular arithmetic

notions of divisibility, primes, prime factorization, gcd, lcm

performing the Euclidean algorithm and using it to find inverses in modular arithmetic (to be covered Friday Sept 2)

Terminology you should be able to explain:

cryptography

coding theory

steganography

plaintext and plaintext space

ciphertext and ciphertext space

key and keyspace

types of cryptanalysis: ciphertext only, known plaintext, chosen plaintext, chosen ciphertext

confusion (property of cryptosystem)

diffusion (property of cryptosystem)

On this quiz we won’t have any proofs, but in future ones, we will.

You should know the broad outlines of the history, but I won’t test you on it.