Send Secret Messages
Encode personal messages, notes, and private communications with a simple substitution cipher.
Shifts each letter by 13. Self-inverse — applying it twice returns the original.
Messages tips
For passing notes or sharing a message only certain people can read, agree on a shift or Vigenère keyword in advance.
Vigenère with a long keyword is significantly harder to crack than Caesar. Use a 8–12 character keyword for practical obscurity.
Send the encoded text via any messaging platform. Only people who know the cipher type and key can decode it without computational help.
These classical ciphers are not cryptographically secure for sensitive data. For real privacy, use end-to-end encrypted messaging apps.
使い方
なぜ私たちのツール？
Also check out…
Encode and Decode ROT13
Use ROT13 to obscure text — the go-to cipher for s
Create Caesar Cipher Puzzles
Encode hidden messages in Caesar cipher for scaven
Learn Classical Cryptography
Explore Caesar, Atbash, and Vigenère ciphers to un
Apply the Atbash Cipher
Reverse the alphabet with Atbash: A becomes Z, B b