FIT5037 - Week 1: Introduction to Network Security & Cryptographic Foundations

The TCP/IP model consists of Application, Transport, Internet, and Network Access layers, which map to the OSI model's Application/Presentation/Session, Transport, Network, and Data Link/Physical layers.

Switches connect local devices (hosts) within the same network/LAN, while routers connect different networks together to enable inter-network data flow.

Data flows down the stack where each layer wraps upper-layer data with headers (e.g., Application Data -> TCP/UDP Segment -> IP Datagram -> Layer 2 Frame -> Bits).

Symmetric ciphers use a single shared key for both encryption and decryption, whereas Asymmetric ciphers use a public key for encryption and a distinct private key for decryption.

AES (Rijndael), Salsa20/ChaCha20, DES, and 3DES.

RSA, Elliptic Curve Cryptography (ECC), Diffie-Hellman, ElGamal, McEliece, and NTRU.

It converts a block cipher into a stream cipher by encrypting successive values of a counter (combined with a nonce) using the key, then XORing the output with the plaintext.

A MAC (often a keyed hash) provides both data integrity and message authentication by allowing the receiver to recalculate and verify the tag using a shared key.