🏛️ Classical Cryptography

Caesar Cipher Calculator

Encrypt and decrypt messages using the legendary cipher of Julius Caesar! Learn the basics of cryptography with this 2000-year-old secret code.

Beginner Friendly

📚 What is a Caesar Cipher?

👑
Named After Julius Caesar
Used by the Roman Emperor to protect military communications around 50 BC
🔄
Simple Shift Cipher
Each letter is shifted by a fixed number of positions in the alphabet
🎓
Perfect for Learning
The foundation of cryptography - easy to understand, fun to use!

The Caesar cipher shifts each letter by a set number of positions. For example, with a shift of 3: A becomes D, B becomes E, C becomes F, and so on. It's like having a secret decoder ring! 🕵️‍♂️

🔐 Encode / Decode

with shift

📊 Analysis

Characters:
Words:
Letters:
Security: Very Low

⚔️ Famous Caesar Cipher Examples

👑 Caesar's Victory Message
"YHQL YLGL YLFL"
Shift 3 • Try clicking to decode this famous quote!
🗡️ Et Tu, Brute?
"HW WX EUXWH"
Shift 3 • Caesar's last words in cipher
🎮 Modern Secret
"FUBC FRPH OHHWV WRGDB"
Shift 3 • A message from today

The History of the Caesar Cipher

The Caesar cipher is named after Julius Caesar, who, according to Suetonius, used it with a shift of three to protect messages of military significance. While Caesar's was the first recorded use of this type of cipher, other substitution ciphers were used even earlier.

The cipher is one of the simplest and most widely known encryption techniques. However, it is also one of the easiest to break. The frequency of letters in the encrypted message can be analyzed to quickly deduce the shift key. Despite its simplicity, the Caesar cipher is an excellent introduction to the world of cryptography.

Cryptography Basics

Algorithm

The algorithm is the set of rules used to encrypt and decrypt a message. In this case, the algorithm is to shift each letter of the alphabet by a certain number of places.

Key

The key is the secret information that is used to encrypt and decrypt the message. For the Caesar cipher, the key is the shift number (e.g., 3).

Ciphertext

The ciphertext is the encrypted message. It's what you would send to your recipient.

Frequently Asked Questions

Is the Caesar cipher secure?

No, the Caesar cipher is not secure by modern standards. It can be easily broken using a technique called frequency analysis. However, it's a great way to learn the basic principles of cryptography.

What is a ROT13 cipher?

ROT13 is a special case of the Caesar cipher where the shift is 13. The advantage of ROT13 is that it's its own inverse: the same algorithm is used for both encrypting and decrypting.

Where is the Caesar cipher used today?

While not used for serious security, the Caesar cipher is sometimes used in a casual way to obscure spoilers or puzzle answers online. It's also a popular tool for teaching basic cryptography concepts.