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Foundations · Beginner · 4 min

The CIA triad

The three goals every security control serves: keep data secret, correct and available.

What it is

Security has three core goals, the CIA triad. Confidentiality means only the right people can see data (passwords, encryption, access control). Integrity means data is correct and hasn't been tampered with (hashes, digital signatures, change control). Availability means systems are up when people need them (backups, redundancy, DDoS protection). Almost every control you'll meet protects one or more of these, and they can pull against each other: locking something down tightly (confidentiality) can make it harder to reach (availability).

Real case · Ongoing

Ransomware hits all three

A ransomware attack is a neat illustration: encrypting the files destroys availability, stealing a copy first breaks confidentiality, and altering or deleting data breaks integrity. That's why it's treated as a top business risk, not just an IT problem.

How defenders stop it

  • Confidentiality: encryption, strong authentication and least-privilege access
  • Integrity: hashing, digital signatures, input validation and change management
  • Availability: tested backups, redundancy, capacity planning and DDoS protection
  • Balance the three: the right level depends on what the data is worth

Try it yourself

Encryption & hashing lesson

Check yourself

1. Which part of the CIA triad does encrypting a file protect?

  1. Confidentiality
  2. Integrity
  3. Availability
  4. None of them
Show answer

Confidentiality. Encryption keeps data secret, so only someone with the key can read it. That's confidentiality.

2. A website is knocked offline by a flood of traffic. Which goal has been attacked?

  1. Availability
  2. Confidentiality
  3. Integrity
  4. Authentication
Show answer

Availability. If people can't reach the system when they need it, availability has failed. A DDoS attacks availability.

3. You compare a downloaded file's hash to the published one and they match. What have you confirmed?

  1. Its integrity: it wasn't changed
  2. Its confidentiality
  3. Its availability
  4. Who created it
Show answer

Its integrity: it wasn't changed. A matching hash shows the file is unchanged, which is integrity. (Proving who made it needs a signature.)

Answer them in the app to earn XP.

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