Enigma

A simple straightforward crypto tool emulating the famous Enigma machine.

License

This software and its source code are distributed under the MIT license.

Author

Developed by Petr Mánek, Charles University in Prague in 2014.

See also

Here are few interesting articles I used when developing this software:

• Enigma machine
• Rotor and reflector wiring
• Bombe attack

Documentation

Usage: enigma [parameters: -e|-d|-c|-h] [configuration: -r|-rf|-p|-ic|-ec|-gc] [flags: -s|-a]

Parameters

• -e --encrypt encrypts data from stdin, the ciphertext is dumped into stdout
• -d --decrypt decrypts ciphertext from stdin, the data is dumped into stdout
• -c --crack attempts to crack the code with brute force, the configuration section is used as a pool of choices on which to base the attack. Assumes the code is successfully cracked, when a regex provided as a value for this parameter matches at least one group in the message.
• -h --help displays this message

Configuration

• -r --rotors sets rotors in visible order (as seen on the physical machine, electrical current enters and exits the last rotor)

    Rotors can be specified by:
    1) Rotor name, all recognized rotor names are:
                    - c1, c2, c3, (Commercial Enigma A, B - 1924)
                    - gr1, gr2, gr3, (German Railway, Rocket - 1941)
                    - k1, k2, k3, (Swiss K - 1939)
                    - w1, w2, w3, w4, w5, w6, w7, w8, (military rotors - 1930-1939)
                    - w_beta, w_gamma (military rotors - 1940-1942)
  
    2) Explicit rotor wiring (any permutation of 26 alphabetic letters ABCDEFGHIJKLMNOPQRSTUVWXYZ without fixed point)
  
    Additional:
        - to set turnover points, add indices 0-25 and / before the wiring (named rotors have turnover points already set up)
          (index n means that when the rotor is stepping from n to n+1, turnover will occur)
          e.g. 8/12/18/FKQHTLXOCBJSPDZRAMEWNIUYGV
  
        - to specify a starting offset, add : and index 0-25 after the name or wiring
          (starting offset 0 means "as-is")
          e.g. c1:23, FKQHTLXOCBJSPDZRAMEWNIUYGV:17
  
        - default turnover points are none (unless you're using a named rotor), default starting offset is 0
  
        - you can specify as many rotors as you like, but keep in mind that a lot of them might slow down the encryption/decryption process
  
        - separate all rotors by a comma without space
  
    Example usage: -r w8:19,k3,1/8/19/FKQHTLXOCBJSPDZRAMEWNIUYGV:3
  

• -rf --reflector sets the reflector

    Reflector can be specified by:
    1) Reflector name, all recognized reflector names are:
                    - gr_ukw (German Railway, Rocket - 1941),
                    - k_ukw (Swiss K - 1939)
                    - w_ra, w_rb, w_rc (military rotors - 1930-1942)
                    - w_rbt, w_rct (thin versions of military rotors B and C)
  
    2) Explicit reflector wiring (same as with rotors, but the permutation has to be involution = inverse to itself)
        Here are few examples of what's a valid reflector wiring (only 4 letters are used for clarity)
        e.g. ABCD is valid, DBCA is valid, ACBD is valid, CBAD is valid, BCDA is invalid
  
    Additional:
        - similarly to rotors, you can specify offset of a reflector by adding : and index 0-25
          e.g. w_ra:21, YRUHQSLDPXNGOKMIEBFZCWVJAT:6
  
        - unlike rotors, the reflector does not change offset during the encryption/decryption process
  

• -p --plugs configures the plugboard

    Plugboard swaps pairs of letters as they enter the rotor assembly, these letters are separated by commas (without spaces), and cannot repeat.
    e.g. AD,PL,FY
  
    Additional:
        - since the swap occurs bidirectionally, the order of the letters doesn't matter (AD = DA, what's more AD,PL = PL,AD)
  

• -ec --export-config dumps current configuration into a specified file

• -ic --import-config reads configuration from specified file

• -gc --gen-config generates random secure configuration (7 rotors, 5 plugs)

Flags

• -s --strict will omit any non-alphabetic chars from the ciphertext (more secure, less readable), used only when encrypting
• -a --accelerate will attempt to accelerate all calculations using the GPU (OpenCL-compatible hardware required)