Caesar Cipher
What is a Caesar Cipher?
Caesar cipher is a substitution cipher that shifts each letter in the plaintext by a fixed number of positions in the alphabet.
How to En\De using Caesar Cipher
Encryption formula:
E(x) = (x + k) mod 26
Decryption formula:
D(x) = (x - k) mod 26
Where:
• x: letter position (A=0, B=1, C=2, ...)
• k: shift value (key)
• mod 26: ensures result stays within alphabet range
• E(x): encrypted letter position
• D(x): decrypted letter position
Example word "HELLO" with k=3:
• H (position 7):
E(7) = (7 + 3) mod 26
= 10 mod 26
= 10 (letter K)
• E (position 4):
E(4) = (4 + 3) mod 26
= 7 mod 26
= 7 (letter H)
• L (position 11):
E(11) = (11 + 3) mod 26
= 14 mod 26
= 14 (letter O)
• L (position 11):
E(11) = (11 + 3) mod 26
= 14 mod 26
= 14 (letter O)
• O (position 14):
E(14) = (14 + 3) mod 26
= 17 mod 26
= 17 (letter R)
Result: HELLO → KHOOR