Encrypt or decrypt text using Caesar cipher, Vigenere cipher, or ROT13
One of the oldest known encryption methods, used by Julius Caesar. Each letter is shifted by a fixed number. For example, with shift 3: A becomes D, B becomes E, etc.
A more advanced cipher using a keyword. Each letter of the keyword determines the shift for the corresponding letter. This creates a polyalphabetic cipher that is harder to break.
A special case of Caesar cipher with a fixed shift of 13. Since 13 is half of 26 (alphabet length), applying ROT13 twice returns the original text. Common for hiding spoilers online.
Security Note: These classical ciphers are educational tools and should not be used for protecting sensitive information. For real security, use modern encryption standards like AES.