A postcard crossing the world
You send a message to a friend. It crosses many machines you do not own. Any one of them could read it, change it or copy it.
Data on the move is called data in transit. Today you learn how to guard it.
Key words
| Word | What it means |
|---|---|
| Data in transit | Data that is moving from one place to another. |
| CIA triad | Confidentiality, integrity and availability: the three goals of security. |
| Confidentiality | Only the right people can read the data. |
| Integrity | The data has not been changed without permission. |
| Availability | The right people can use the data when they need it. |
| Eavesdropping | Secretly listening to or copying data as it travels. |
| Asymmetric encryption | Encryption with a pair of keys: a public one and a private one. |
| Authenticity | Proof that data really came from who it says. |
| Non-repudiation | The sender cannot later deny they sent it. |
| Cryptography | The science of making and breaking codes. |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can use the CIA triad to find what data in transit needs, and say how asymmetric encryption and cryptography protect it.
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.
Step 1: find out what the data needs
Start with the CIA triad. Ask three questions about the data.
Confidentiality: who may read it? Integrity: what harm if it changed? Availability: what harm if it could not arrive?
The answers tell you how strong the protection must be.
Step 2: stop eavesdropping
Eavesdropping is listening in as data travels. The defence is encryption.
Asymmetric encryption gives each person two keys. Lock a message with the other person's public key. Only their private key can open it. No secret has to be sent first.
Check: needs and eavesdropping
Have a go
Check: needs and eavesdropping
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.