How a Caesar Cipher Works

Basic Concept

The Caesar Cipher is a simple encryption method where each letter in the plaintext is shifted a fixed number of places in the alphabet.

Example (Shift = 3)

Plaintext Letter	Shifted 3 Places	Ciphertext Letter
H	K	K
E	H	H
L	O	O
L	O	O
O	R	R

Encryption Formula

For a given letter X, shift S, and the 26-letter English alphabet:

• Encryption: C = (X + S) mod 26
• Decryption: X = (C - S) mod 26

Handling Edge Cases

• Uppercase letters remain uppercase.
• Lowercase letters remain lowercase.
• Spaces, punctuation, and numbers remain unchanged.

Security

The Caesar Cipher is not secure for modern encryption because there are only 25 possible shifts, making it easy to brute-force decrypt.