create self signed ssl pem file

requirements.txt

pyopenssl
twisted
cherrypy
service_identity

ssl_gen.py

import os, time, tempfile
from twisted.internet import ssl
import OpenSSL

def generate_ssl_pem(cn):
    # req
    dn = ssl.DistinguishedName(commonName=cn)
    keypair = ssl.KeyPair.generate()
    req = keypair.certificateRequest(dn)

    # sign
    verify = lambda dn: True
    serialno = int(time.time())
    issuer = ssl.DistinguishedName(commonName=cn)
    certData = keypair.signCertificateRequest(issuer, req, verify, serialno)
    cert = keypair.newCertificate(certData)

    return cert.dumpPEM()


def verify_ssl_pem_file(cn, filename):
    if not os.path.exists(filename):
        return False
    pem = open(filename, 'rb').read()
    cer = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM, pem)
    for pair in cer.get_subject().get_components():
        if pair == ('CN', cn):
            return True
    return False


def generate_ssl_pem_file(cn, filename=None):
    if filename:
        if verify_ssl_pem_file(cn, filename):
            return filename
        else:
            f = open(filename, 'wb')
    else:
        f = tempfile.NamedTemporaryFile(delete=False)
        filename = f.name

    with f:
        f.write(generate_ssl_pem(cn))
        print 'SSL: pem generated for', cn
        return filename


if __name__ == '__main__':
    from cherrypy.wsgiserver import CherryPyWSGIServer
    from cherrypy.wsgiserver.ssl_builtin import BuiltinSSLAdapter
    from wsgiref.simple_server import demo_app

    domain = 'www.example.com'
    pemfile = generate_ssl_pem_file(domain)
    https = CherryPyWSGIServer(('0.0.0.0', 443), demo_app, server_name=domain)
    https.ssl_adapter = BuiltinSSLAdapter(pemfile, pemfile, None)

    print('Server running as: https://0.0.0.0:443/')
    https.start()