Explain network security methods (encryption, firewalls)

14 Communications Technology

Network Security Methods

Network security protects data as it travels across the internet. Two main tools are encryption (scrambling data) and firewalls (guarding the network).

Encryption

Think of encryption as writing a diary in a secret code. Only someone with the right key can read it. 🔒

• 🔑 Symmetric encryption uses the same key for both writing and reading. Fast but the key must be shared securely.
• 🔐 Asymmetric encryption uses a public key to encrypt and a private key to decrypt. Slower but safer for key exchange.
• 📚 Common algorithms: AES, DES, 3DES, RSA, ECC.

Encryption Types

Mathematically, encryption can be shown as:

$E_{k}(m)$ – encrypt message $m$ with key $k$

$D_{k}(c)$ – decrypt ciphertext $c$ with key $k$

Firewalls

A firewall is like a guard at a castle gate. It decides which visitors (data packets) are allowed in or out based on rules. 🛡️

• 🕹️ Packet filtering checks the header of each packet.
• 🔄 Stateful inspection remembers the state of connections.
• 🧩 Application layer filtering looks at the content of the packet.

Firewall Types

1. Hardware firewalls – physical devices between networks.
2. Software firewalls – installed on individual computers.
3. Cloud firewalls – virtual appliances in the cloud.