What encryption does, the Caesar cipher by hand, why it is easy to break, and how password length changes the work for an attacker.
What you will learn
- Encrypt and decrypt with a Caesar cipher
- Find the key from a plaintext and ciphertext
- Explain why the Caesar cipher is weak
- Explain why passwords are stored as hashes
Encryption
Encryption scrambles plaintext into ciphertext using a key.
Without the key, intercepted data is useless to an attacker. HTTPS, Wi-Fi (WPA2 and WPA3) and encrypted disks all use it.
Websites should not store passwords at all: they store a hash, a value worked out from the password that cannot be turned back. At login they hash what you type and compare.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- Encryption
- The Caesar cipher
- Try it: Encrypt a word
7 practice questions, marked as you go; about 20 minutes in all.
Key terms
Encryption, Plaintext, Ciphertext, Key, Hash
In this unit: Cyber security
Malware and social engineering, brute force, denial of service, SQL injection and interception, and the defences against them, with Caesar ciphers and password maths.
- Malware and social engineering
- Attacks on systems
- Protecting systems
- Encryption and the Caesar cipher
- Extended answers