2.1 Symmetric encryption methods2.2 Monoalphabetic cipher2.3 Polyalphabetic cipher2.4 Frequency analysis and coincidence index2.5 Perfect security and the Vernam one-time pad2.6 Asymmetric encryption methods2.7 RSA cryptosystem2.8 Rabin cryptosystem 2.9 Diffie–Hellman key exchange2.10 ElGamal cryptosystem2.11 Cryptographic hash functions