This is the first in a series of missions inspired by classical cryptography. In this mission we will take a look at the Atbash cipher.
Atbash is one of the oldest known ciphers, created in Middle East around 600 B.C.; the first known examples of it can be found in the Dead Sea Scrolls (ancient religious Hebrew manuscripts), where it was used to encrypt certain important names and words.
Atbash is an example of a simple substitution cipher. In this type of ciphers each letter of the message (or plaintext ) is mapped to a single correspinding letter of the ciphertext. in case of Atbash the plaintext alphabet is simply mapped to it's reverse, so that the first letter is replaced with the last, the second letter - with the second to last and so on. For example, the message "Hello, world!" is enciphered to "Swool, dliow!". The substitution table (for Latin alphabet) looks like this:
Plaintext alphabet: abcdefghijklmnopqrstuvwxyz Ciphertext alphabet: zyxwvutsrqponmlkjihgfedcba
To decrypt a message, the same algorithm is applied to the ciphertext.
It's easy to see that Atbash provides virtually no information security. Anyone who intercepts the message encrypted with the Atbash cipher can easily decipher it by applying the same substitution table.
For this mission you need to write a function that encrypts given text with Atbash. Punctuation, whitespaces and other characters should remain unchanged.
Input: plaintext: str
Output: ciphertext: str
atbash('testing') == 'gvhgrmt' atbash('Hello, world!') == 'Svool, dliow!'
CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.
In order to install CheckiO client you'll need installed Python (version at least 3.8)
Install CheckiO Client first:
pip3 install checkio_client
Configure your tool
checkio --domain=py config --key=
Sync solutions into your local folder
(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)
checkio serv -d
Alternatevly, you can install Chrome extension or FF addon
checkio install-plugin --ff
checkio install-plugin --chromium