---
title: "24-network-security"
aliases: 
tags: 
- cosc203
- lecture
---

# what is it?
- confidentiality
	- only sender and reciver should understand message contents
	- encryption
- authentication
	- sender and reciever want to confirm identity of each other
- message integrity
	- sender and reciever want to ensure message not altered (in transit, or afterwards) without detection
- access and availablility
	- services must be accessible and availble to users

sender and recieves:
- any king of onnline communication

what can trudy to
- eavesdrop
- insert messages into connection
- impersonation: fake (spoof) source address (or any field)
- hijacjking "take over" ongoing connection by removing sender or ereciever, inserting himself in place
- denial of service: prevent others from using a service (e.g., by overloading it)

terminology
- m: plaintext message
- 

# Symmetric key crypto

# Public key

# Authentication of devices

# digital signature