Chaocipher is a method of encryption invented by John F. Byrne in 1918 that was never publicly solved.
The algorithm was published in May 2010. These implementations are based on a paper by Moshe Rubin.
The python program chao.py reads the plaintext or ciphertext from
standard input and writes the result to stdout. The --encrypt and --decrypt and --autoencrypt arguments specify the
mode. For --autoencrypt, random left and right alphabets are automatically generated. For --encrypt and --decrypt, you need left and right alphabets set manu8ally using the --left and --right arguments
respectively.
An example of encrypting a file:
cat myfile.txt | python3 chao.py --autoencrypt
An example of decrypting text entered from the terminal:
python3 chao.py --decrypt --left HXUCZVAMDSLKPEFJRIGTWOBNYQ --right PTLNBQDEOYSFAVZKGJRIHWXUMC