ultra 
Cryptanalysis of the Enigma in Rust.
Installation
ultra can be installed from crates.io using Cargo:
$ cargo install ultra
Usage
Encrypt a message with rotors 1-4-2, key setting DOG, and ring setting CAT:
$ ultra --rotor=142 --key=DOG --ring=CAT ${message}Encrypt a message using random Enigma settings:
$ ultra --randomize ${message}Attempt to decrypt a given piece of ciphertext:
$ ultra --decrypt ${message}Note: Decryption relies on quadgram frequencies to infer the original Enigma machine settings; as a result, it is very likely that short messages will be decrypted incorrectly. Additionally, decryption will not work for messages that were encrypted with any plugboard plugs active.
References
This project's quadgram data and decryption algorithm is based on James Lyons' articles about the Enigma machine.
License
ultra is licensed under the MIT License.