- each plain-text letter is replaced with a corresponding ciphertext letter
- very old and ancient method
- easily breakable…
| Letter | Substitution |
|---|---|
| f | p |
| l | e |
| a | o |
| g | a |
flag => peoa
Few examples of shift ciphers are:
- caesar’s cipher
- ROT13
ROT13
- rotate 13 characters
- each character in the english alphabet is shifted with the alphabet that is in the 13th position from current character. The cycle goes on if the 13th position is greater than 26 so it will start from the first position of the alphabet
Attack Vectors
- Bruteforce the characters
- Frequency guessing: We’ll be guessing the letters and replacing it with the possible letters that make up the world. Vowels are most commonly seen in most of the letters.