Three promises of a library
Your college library keeps a record of every book you borrow. It makes three promises.
One: only you and the library see your record. Two: the record is right. Three: you can look at it whenever you need.
Break one promise and the others suffer. Security people call these the CIA triad.
By the end of this lesson
Note
I can explain how confidentiality, integrity and availability depend on each other.
Key words
| Word | What it means |
|---|---|
| Confidentiality | Keeping data private by controlling who has access to it. |
| Integrity | Data has not been tampered with: it is correct and unchanged. |
| Availability | Data and systems are there and useful when needed. |
| Triad | A group of three. |
| Tampering | Changing something without permission. |
| Access control | Rules that decide who may see or change data. |
| Outage | A time when a system does not work. |
| Firewall | A guard that decides which internet traffic may pass. |
| Encryption | Scrambling data so only the right key can read it. |
| Trust | Belief that data is correct and safe to use. |
The cells students fill in are left blank in this preview.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Cycle 1: the three goals
Confidentiality keeps data private. It does this by controlling who has access.
Integrity means the data has not been tampered with. It is the same as it should be.
Availability means the data is there and useful when it is needed. A record that is wrong, or locked away, is not useful.
Worked example: one goal at a time
| Goal | What breaks it | A defence that helps |
|---|---|---|
| Confidentiality | A stranger reads the member list | Access control, encryption, MFA |
| Integrity | A loan record is changed by a thief | Permissions, hashes, audit logs |
| Availability | A power cut or DDoS stops the catalogue | Backups, spare systems, a firewall |
The cells students fill in are left blank in this preview.
Check: which goal is broken?
Have a go
Check: which goal is broken?
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.