This is a basic implementation of the NTRU Cryptosystem completed as university coursework.
Disclaimer: This is not a complete or secure implementation and should not be used as anything other than an educational tool.
Some of the details of this system were taken from https://github.com/jkrauze/ntru , such as certain polynomial coercion operations, and parts of the commandline interface. However, the majority of the program is completely different.
./ntru.py gen [N] [p] [q] [PRIVATE_KEY_FILE] [PUBLIC_KEY_FILE]
./ntru.py enc [PUBLIC_KEY_FILE [CIPHERTEXT] [MESSAGE_FILE]
./ntru.py dec [PRIVATE_KEY_FILE] [CIPHERTEXT_FILE]
./ntru.py att [PUBLIC_KEY_FILE] [CIPHERTEXT_FILE]
The best explanation of how to use the system is to look at the testing script outlined below.
The bash script "test.sh" generates and encrypts a message contained in the "message.txt" file. It then decrypts the ciphertext using the public key, then attacks the cryptosystem with a lattice attack.
Though it should be able to handle any size of text, the program is quite slow and a large plaintext could take a while to encrypt and decrypt.
The attack is only particularly successful for N less that 45.
William Cashman 2019