m6sig / lorenz-cipher-sim Goto Github PK

A fork of https://github.com/RealGrep/lorenz-cipher-sim

Now works on Python3 with better command line interface.
Reduced numbers of LTRS/FIGS symbol to rise the bar for chosen plaintext attack to the same level as the real machine. 
Improve wheel generation speed.
Randomise wheel indicator numbers.

After consulting with the publication BREAKING TELEPRINTER CIPHERS AT BLETCHLEY PARK: An edition of I. J. Good, D. Michie and G. Timms' GENERAL REPORT ON TUNNY WITH EMPHASIS ON STATISTICAL METHODS (1945) Edited and with introductions and notes by James A. Reeds, Whitfield Diffie and J. V. Field, The python code in lorenz-sz40.py matches the cipher machine Lorenz Schlüsselzusatz 40, aka Lorenz Sz40.

Usage:
$ python3 lorenz-sz40.py [-h] [--keygen <key file>]
                         [--encrypt <input file> <key file> <output file>]
                         [--decrypt <input file> <key file> <output file>]
                         [--readtape <input file>]

optional arguments:
  -h, --help            show this help message and exit
  --keygen <key file>   Creates a random key file with normal SZ40 teeth
                        counts and sets random indicators. Edit the file to
                        suit.
  --encrypt <input file> <key file> <output file>
                        Encode ASCII plaintext to Baudot code (5 bits per
                        byte) and encrypt with wheel settings in key file,
                        writing ciphertext to output file.
  --decrypt <input file> <key file> <output file>
                        Decrypt the input file with wheel settings in key
                        file, decode from Baudot code and and output ASCII
                        plaintext to output file.
  --readtape <input file>
                        Read input file in Baudot code and display ASCII
                        equivalent.

Example:
  python3 lorenz.py --keygen <key file>
  python3 lorenz.py --encrypt <input file> <key file> <output file>
  python3 lorenz.py --decrypt <input file> <key file> <output file>
  python3 lorenz.py --readtape <input file>