import sys

from cryptography.hazmat.primitives import serialization, hashes
from cryptography.hazmat.primitives.asymmetric import rsa, padding


def decryptFile(private_key, cipher_text):
	plain_text = private_key.decrypt(
		cipher_text,
		padding.OAEP(
			mgf=padding.MGF1(algorithm=hashes.SHA256()),
			algorithm=hashes.SHA256(),
			label=None
		)
	)
	return plain_text


def load_private_key(file, paswd=None):
	with open(file, 'rb') as key_file:
		private_key = serialization.load_pem_private_key(
			key_file.read(),
			password=paswd,
		)

	return private_key