get certificate issuer info in python

gistfile1.txt

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Sun Jan 26 09:43:37 2020

@author: bockor

https://stackoverflow.com/questions/30862099/how-can-i-get-certificate-issuer-information-in-python
https://gist.github.com/ryansb/d8c333eb4a74168474c4
https://kite.com/python/docs/ssl.SSLSocket.getpeercert
"""

import ssl, socket

hostname = 'www.example.com'
ctx = ssl.create_default_context()
s = ctx.wrap_socket(socket.socket(), server_hostname=hostname)
s.connect((hostname, 443))
cert = s.getpeercert()

subject = dict(x[0] for x in cert['subject'])
issued_to = subject['commonName']
issuer = dict(x[0] for x in cert['issuer'])
issued_by = issuer['commonName']
expires_at = cert['notAfter']

print("[+] Certificate issued to: {}".format(issued_to))
print("[+] Certificate issued by: {}".format(issued_by))
print("[+] Cerificate expiry date: {}".format(expires_at))

'''
Output
[+] Certificate issued to: www.example.org
[+] Certificate issued by: DigiCert SHA2 Secure Server CA
[+] Cerificate expiry date: Dec  2 12:00:00 2020 GMT
'''