Contents 1. Cryptography: an overview 1.1 Elementaru ciphers 1.2 Enigma 1.3 A review of modular arithmetic and Zn 1.4 The hill cipher 1.5 Attscks on the hill cipher 1.6 Feistel cipher and DES 1.7 A word about AES 1.8 Diffie-hellman public key exchange 1.9 RSA 1.10 Public key exchanges with a group 1.11 Public key exchange using elliptic curve 2. Quantum mechanics 2.1 Photo pol…