Caesar Cipher
Computer Science: Edexcel IGCSE, topic 3.4.2
Caesar Cipher
The Caesar Cipher is a simple encryption method.
To encrypt
- To encrypt text, we must shift each letter by the number of places defined by a shared secret key.
- For example:
- If we have a key of +2 then each letter will be replaced with the letter 3 places ahead of it, i.e. a becomes c, b becomes d, and so on.
- Therefore, "hello" would become "jgnnq".
To decrypt
- To decrypt, simply encrypt with the negative of the key.
- Therefore, "jgnnq" would become "hello".
Security
- The Caesar Cipher is a very weak form of encryption, and would never be used alone in a real-life scenario.
Test yourself on Caesar Cipher
What is the encrypted version of "Cat" with a key of +3?
If the encrypted text is "Czf" and the key is +1, then what is the original text?
Which of these statements about Caesar cypher are true?
A Caesar cypher with a key of +13 has the same encryption and decryption method.
True or false?