Generating a CSR in Python

Question

I'm trying to generate a CSR in Python without using OpenSSL. If someone could point in the right direction, I'd be very grateful.

Answer 1

I assume you don't want to use the command line openssl itself and a Python lib is ok.

Here is an helper function I wrote to create a CSR. It returns the private key from the generated key pair and the CSR. The function depends on pyOpenSSL.crypto.

def create_csr(self, common_name, country=None, state=None, city=None,
               organization=None, organizational_unit=None,
               email_address=None):
    """
    Args:
        common_name (str).

        country (str).

        state (str).

        city (str).

        organization (str).

        organizational_unit (str).

        email_address (str).

    Returns:
        (str, str).  Tuple containing private key and certificate
        signing request (PEM).
    """
    key = OpenSSL.crypto.PKey()
    key.generate_key(OpenSSL.crypto.TYPE_RSA, 2048)

    req = OpenSSL.crypto.X509Req()
    req.get_subject().CN = common_name
    if country:
        req.get_subject().C = country
    if state:
        req.get_subject().ST = state
    if city:
        req.get_subject().L = city
    if organization:
        req.get_subject().O = organization
    if organizational_unit:
        req.get_subject().OU = organizational_unit
    if email_address:
        req.get_subject().emailAddress = email_address

    req.set_pubkey(key)
    req.sign(key, 'sha256')

    private_key = OpenSSL.crypto.dump_privatekey(
        OpenSSL.crypto.FILETYPE_PEM, key)

    csr = OpenSSL.crypto.dump_certificate_request(
               OpenSSL.crypto.FILETYPE_PEM, req)

    return private_key, csr