How to load a public RSA key into Python-RSA from a file?

Question

I generated a private and a public key using OpenSSL with the following commands:

openssl genrsa -out private_key.pem 512
openssl rsa -in private_key.pem -pu         


        

Answer 1

To load an OpenSSL generated public key file with python-rsa library, try

with open('public_key.pub', mode='rb') as public_file:
    key_data = public_file.read()
    public_key = rsa.PublicKey.load_pkcs1_openssl_pem(key_data)

Answer 2

Python-RSA uses the PEM RSAPublicKey format and the PEM RSAPublicKey format uses the header and footer lines: openssl NOTES

-----BEGIN RSA PUBLIC KEY-----
-----END RSA PUBLIC KEY-----

Output the public part of a private key in RSAPublicKey format: openssl EXAMPLES

 openssl rsa -in key.pem -RSAPublicKey_out -out pubkey.pem

Answer 3

If on Python3, You also need to open the key in binary mode, e.g:

with open('private_key.pem', 'rb') as privatefile:

Answer 4

from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.backends import default_backend


def load_keys():
    with open("public.pem", "rb") as f:
        public = serialization.load_pem_public_key(
            f.read(), backend=default_backend()
        )
    with open("private.pem", "rb") as f:
        private = serialization.load_pem_private_key(
            f.read(), None, backend=default_backend()
        )
    return private, public

Answer 5

You can generate private key by ssh-keygen:

ssh-keygen -t rsa

and generate public key like this:

ssh-keygen -e -m pem -f xxx > pubkey.pem

http://blog.oddbit.com/2011/05/08/converting-openssh-public-keys/