CIA triad consists of Confidentiality, Integrity and Availability. These three terms are used to determine the overall security posture of an organization.
Confidentiality: This means that data should be accessible to the authorized parties only. If any unauthorized party is able to access the data which he/she is not allowed to then it breaches confidentiality. Confidentiality can be achieved via Encryption.
Example: Alice is chatting with her friend on whatsapp in a cafe which offers free WiFi network. Bob, who is also in the cafe and connected to the same WiFi network cannot see what Alice is sending to her friend. This is due to the encryption that is being used by Whatsapp.
Integrity: When data is sent between two parties it should be 100 % accurate without any modification / tampering being done during its transmission. When the data is modified or tampered in between then it can lead to integrity issues. Integrity can be achieved via Hashing.
Example: Alice downloads a Kali linux iso from Kali’s official website. On the website besides the download link the checksum (hash value) of the file is also provided. Once Alice has downloaded the file she can calculate the hash value of it and compare it with the hash value provided by Kali’s website. If they both match then the file is free from modification / tampering and is 100% accurate. If the hash value doesnt match then there is something wrong with the file and it should be deleted.
Availability: This simply means that the data should be available to the authorized users at all times. When a user of a website is trying to access the digital services it offers, he should be able to do that without any problems. If for some reason the website is not able to provide its services then it is an issue of availability. Redundancy, Backup etc are different ways in which availability can be maintained.
Example: There is a website which provides cloud gaming services to its customers. The website claims that its service runs 24/7 and asks for 5$ for a monthly subscription. The data center of the website gets struck by a major power outage which leads to the servers being shut down. This affects the availability and prevents the legitimate users of the website from accessing the services.