Caesar Cipher Encoder & Decoder
Shift letters through the alphabet to encode secret messages — or brute-force all 25 shifts to crack one.
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How the cipher works
Every letter is moved a fixed number of places through the alphabet, wrapping from Z back to A. Case is preserved and everything that isn't a letter is left alone. With the classic shift of 3, ATTACK AT DAWN becomes DWWDFN DW GDZQ.
Cracking it with brute force
Because there are only 25 possible shifts, an unknown key is no obstacle: generate all 25 decodings and pick the one that reads as English. This is also why the Caesar cipher is a teaching tool, not real cryptography — a modern computer tries every shift in under a millisecond.
FAQ
What is a Caesar cipher?
The Caesar cipher is one of the oldest encryption techniques: each letter of the message is shifted a fixed number of positions through the alphabet. With a shift of 3, A becomes D, B becomes E, and
HELLO becomes KHOOR. Decoding reverses the shift.Is the Caesar cipher secure?
No — not even slightly. There are only 25 possible shifts, so any message can be brute-forced in milliseconds. It is useful for puzzles, CTF challenges, and learning how substitution ciphers work, but never for protecting real secrets.
How do I decode a message when I don't know the shift?
Brute-force it: try all 25 shifts and look for the one that produces readable English. This tool's brute-force table shows every shift's result at once — click any row to adopt that shift.
Does it work with numbers, spaces and symbols?
Only A–Z and a–z are shifted; case is preserved. Numbers, spaces, punctuation and all other characters pass through unchanged, which is the classic behavior of the cipher.
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