How can I get certificate issuer information in python?

Question

I want the information to be "issued" from a certificate in python. I am trying to use the SSL and SSLSocket library, but this did not happen.

Answer 1

Updated Answer

If you can connect to a remote server, you can use the standard library module ssl:

import ssl, socket

hostname = 'google.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']

>>> issued_to
u'*.google.com'
>>> issued_by
u'Google Internet Authority G2'

Original answer

Use pyOpenSSL .

from OpenSSL import crypto

cert_file = '/path/to/your/certificate'
cert = crypto.load_certificate(crypto.FILETYPE_PEM, open(cert_file).read())
subject = cert.get_subject()
issued_to = subject.CN    # the Common Name field
issuer = cert.get_issuer()
issued_by = issuer.CN

You can also access additional components, for example. organization ( subject.O/ issuer.O), organizational unit ( subject.OU/ issuer.OU).

, crypto.FILETYPE_ASN1 crypto.FILETYPE_PEM.

Answer 2

requests, :

#!/usr/bin/python
# -*- coding: utf-8 -*-


from requests.packages.urllib3.contrib import pyopenssl as reqs


def https_cert_subject_alt_names(host, port):
    """Read subject domains in https cert from remote server"""

    x509 = reqs.OpenSSL.crypto.load_certificate(
        reqs.OpenSSL.crypto.FILETYPE_PEM,
        reqs.ssl.get_server_certificate((host, port))
    )
    return reqs.get_subj_alt_name(x509)

if __name__ == '__main__':
    domains = https_cert_subject_alt_names("www.yahoo.com", 443)
    print(domains)

:

[('DNS', '*.www.yahoo.com'), 
 ('DNS', 'www.yahoo.com'), 
 ('DNS', 'add.my.yahoo.com'), 
 ('DNS', 'au.yahoo.com'), 
 ('DNS', 'be.yahoo.com'), 
 ('DNS', 'br.yahoo.com'), 
 ('DNS', 'ca.my.yahoo.com'), 
 ('DNS', 'ca.rogers.yahoo.com'), 
 ('DNS', 'ca.yahoo.com'), 
 ('DNS', 'ddl.fp.yahoo.com'), 
 ('DNS', 'de.yahoo.com'), 
 ...
 ('DNS', 'mbp.yimg.com')]

Answer 3

import os
import re
os.system('keytool -printcert -sslserver google.com:443 >cert.txt')
fh = open("cert.txt", "r")
content = fh.readlines()
fh.close()
content = content[2]
m = re.search('CN=(.+?),', content)
if m:
    found = m.group(1)
print found