Ciphers
Computer Science: Edexcel IGCSE, topic 3.4.3
Ciphers
Some ciphers are harder to crack than others. Pigpen, Vigenere and rail fence ciphers are stronger than Caesar ciphers.
Pigpen cipher
- The pigpen cipher is a simple substitution cipher.
- Rather than replacing letters with other letters, the pigpen cipher replaces letters with symbols.
- The image above represents the word "The".
Vigenère cipher
- Vigenère cipher is a polyalphabetic substitution cipher.
- Multiple Caesar cipher keys are shared between two parties.
- The first letter is encrypted using the first key, the second with the second key and so on until all of the text is encrypted.
- This protects against frequency analysis.
Rail fence cipher
- Rail fence cipher is a transposition cipher.
- In the rail fence cipher words are written out letter-by-letter in a zig-zag pattern.
- Each row is then read, which scrambles up the letters.
- If the recipient knows how many rows there originally were, then they can decrypt the message.
Test yourself on Ciphers
Which type of cipher is Vigenère cipher?
Which type of cipher is rail fence cipher?