I am trying to write a Python3 program which will show me all information which is included in a public key certificate, similar to the following linux command:
openssl x509 -in website.com.pem -text
which will return a result similar to
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
04:7a:f7:95:47:c0:7d:0f:ef:80:a5:b2:1f:51:e3:63
Signature Algorithm: sha256WithRSAEncryption
Issuer: C = GB, ST = Greater Manchester, L = Salford, O = COMODO CA Limited, CN = COMODO RSA Domain Validation Secure Server CA
Validity
Not Before: Mar 12 00:00:00 2018 GMT
Not After : Mar 11 23:59:59 2020 GMT
Subject: OU = Domain Control Validated, OU = PositiveSSL, CN = acs.cdroutertest.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
as shown on the following website: https://support.qacafe.com/knowledge-base/how-do-i-display-the-contents-of-a-ssl-certificate/
I was trying the Cryptography or pyopenssl modules in python3 already, and was able to import the certificate and display e.g. the public key. However i did not find a way to go through all information available and just display them, without having to write a print() statement for every field that might or might not be available in the certificate.
Does anybody have an idea how to push me into the right direction?
Its appreciated, thank you!
A solution that has actually slipped my attention is the use of the module asn1tools
import asn1tools
foo = asn1tools.compile_files("x509.asn")
output = foo.decode("Certificate", cert)
Only all ASN.1 definitions needed for X509 have to be available in the file x509.asn (available via the respective RFC), while "cert" holds the bytestring.
The result will be a python dict with all the information contained, without having to loop through anything or missing some unusual parameters