#!/usr/bin/python3

'''
Creates RSA public and private keys using python, saves keys into public.pem and private.pem respectively

Author: Tim Pierson, Dartmouth CS55, Winter 2021
				Based Wenliang Du https://github.com/kevin-w-du/BookCode/tree/master/Public_Key_Cryptography
Usage: 	python3 rsa_key_gen.py <password>
				where password used to protect the keys generated
		python3 rsa_key_gen.py cs55
'''


import sys
from Crypto.PublicKey import RSA
key_size = 2048

if __name__ == '__main__':
	#usage check: make sure we got a filename to read
	if len(sys.argv) != 2:
		print("Usage: python3 rsa_key_gen.py <password>")
		print("Did you provide a password?")
		exit()

	print("Generating keys using password",sys.argv[1])
	key = RSA.generate(key_size)
	pem = key.export_key(format='PEM', passphrase=sys.argv[1])

	#write private key 
	print("Writing private.pem")
	f = open('private.pem','wb')
	f.write(pem)
	f.close()

	#write public key
	print("Writing public.pem")
	pub = key.publickey()
	pub_pem = pub.export_key(format='PEM')
	f = open('public.pem','wb')
	f.write(pub_pem)
	f.close()