Text Encryption

How does text encryption work?

Encryption transforms readable text (plaintext) into unreadable text (ciphertext) using an algorithm and a key. Decryption is the reverse operation. The algorithms shown here are classical ciphers for educational purposes — they are not secure for professional use (use AES or ChaCha20 for sensitive data).

Caesar cipher and ROT13

The Caesar cipher shifts each letter of the alphabet by a fixed number of positions (the key). With a key of 3, A→D, B→E, etc. It is one of the oldest known algorithms, used by Julius Caesar for military communications. ROT13 is a special case with a shift of 13 — applying ROT13 twice returns the original text.

Vigenère cipher

The Vigenère cipher uses a keyword to apply multiple Caesar shifts cyclically. With key "KEY", the 1st letter is shifted by 10 (K), the 2nd by 4 (E), the 3rd by 24 (Y), then repeats. It is much more robust than Caesar because the same letter can be encrypted differently depending on its position.