#!/usr/bin/env python3

import Crypto.PublicKey.ECC as ECC
from Crypto.Random.random import getrandbits
from Crypto.Util.number import bytes_to_long
from snowden_papers import state_secrets

params = ECC.generate (curve='Curve25519')
Q = params.pointQ
P = Q * getrandbits (16)
s = getrandbits (112)

def f():
	global s
	r = (P * s).x
	s = (P * r).x
	return int((Q * r).x >> 16)

print ('Welcome to the Bullrun(TM) encryption machine!')
print (f'Serial number: {P.x}')
print (f'Model number: {Q.x}')

while True:
	print ('What would you like to do?')
	print ('1) Encrypt your own secrets.')
	print ('2) Read state secrets.')
	print ('3) Exit.')

	action = input ('> ')
	if action == '1':
		try:
			num = int (input ('Enter your secret: '))
		except ValueError:
			print ('We knew that already.')
			continue
		print (f'Here is your encrypted secret: {num ^ f()}')
	elif action == '2':
		print (f'Here are some state secrets: {bytes_to_long (state_secrets) ^ f()}')
	elif action == '3':
		print ('Goodbye.')
		break
	else:
		print ('Invalid action.')