1. def save_key_to_file(key, filename):
2.     # Check if the key is a private key
3.     if isinstance(key, rsa.RSAPrivateKey):
4.         # Serialize the private key in PEM format with PKCS8
5.         pem = key.private_bytes(
6.             encoding=serialization.Encoding.PEM,
7.             format=serialization.PrivateFormat.PKCS8,
8.             encryption_algorithm=serialization.NoEncryption()
9.         )
10.     else:
11.         # Serialize the public key in PEM format
12.         pem = key.public_bytes(
13.             encoding=serialization.Encoding.PEM,
14.             format=serialization.PublicFormat.SubjectPublicKeyInfo
15.         )
16.  
17.     # Write the serialized key to a file using binary. use [.pem] file extension
18.     with open(filename, 'wb') as file:
19.       file.write(pem)
20.  
21.  
22. def load_private_key_from_file(filename):
23.     # read the saved pem file in the pem variable
24.     with open(filename, 'wb') as file:
25.       pem = file.read()
26.     ## line 1
27.         ## line 2
28.     private_key = serialization.load_pem_private_key(
29.         pem,
30.         password=None,
31.         backend=default_backend()
32.     )
33.     return private_key
34.  
35. def load_public_key_from_file(filename):
36.     # read the saved pem file in the pem variable
37.     with open(filename, 'wb') as file:
38.       pem = file.read()
39.     ## line 1
40.         ## line 2
41.     public_key = serialization.load_pem_public_key(
42.         pem,
43.         backend=default_backend()
44.     )
45.     return public_key
46.  
47. private_key, public_key = generate_keys()
48. save_key_to_file(private_key,"private_rsa.pem")
49. save_key_to_file(public_key,"public_rsa.pem")
50.