ATBASH Cipher

<p align="center"> <!-- replace image by project Image --> <img height="128" src="https://cryptools.github.io/img/atbash.svg"> </p> <p align="center"> <img src="https://cryptools.github.io/img/status/implemented.svg"> <img src="https://img.shields.io/travis/CrypTools/ATBASHCipher.svg"> <img src="https://img.shields.io/github/license/Cryptools/ATBASHCipher.svg"> <img src="https://img.shields.io/github/contributors/Cryptools/ATBASHCipher.svg"> </p>

A simple linear cipher originally used on the Hebrew alphabet. Atbash is considered a special case of Affine Cipher, a monoalphabetic substitution cipher.

How it works

Encoding

The ATBASH cipher is pretty simple, and all its does is reverse the letters in the alphabet: A becomes Z, B becomes Y, ..., Y becomes B, Z becomes A.

Here's the full table:

| A | B | C | D | E | F | G | H | I | J | K | L | M | |---|---|---|---|---|---|---|---|---|---|---|---|---| | Z | Y | X | W | V | U | T | S | R | Q | P | O | N |

| N | O | P | Q | R | S | T | U | V | W | X | Y | Z | |---|---|---|---|---|---|---|---|---|---|---|---|---| | M | L | K | J | I | H | G | F | E | D | C | B | A |

Encoding the word crypto, we get:

C R Y P T O
X I B K G L

Decoding

We can observe that applying the code twice to a message letter, will leave us with the original message. To decrypt, we just have to re-apply the code.

X I B K G L
C R Y P T O

Cons

• Pretty simple and famous cipher.
• Frequency analysis can be used to crack the code, if the message is long enough.

Implementations

| Language | Encrypt | Decrypt | |----------------|------------------------------------|------------------------------------| | C | ATBASHCipher.c| ATBASHCipher.c| | C++ | main.cpp | main.cpp | | Javascript | encrypt.js | decrypt.js | | Python | encrypt.py | decrypt.py | | Swift | lib.swift | lib.swift |

Running the tests

Tests are automatically handled by Travis CI.

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Authors

Made with ❤️ at CrypTools.

See also the list of contributors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE.md file for details