Skip to main content

Parse x509v3 certificates and PKCS7 signatures

Project description

This is a fork of a fork of a fork of the original project:

py3x509 - Python library for parsing X.509 Copyright (C) 2009-2012 CZ.NIC, z.s.p.o. (

Updates by me rename the module to ‘x509’ and update to Python3 only.

Copyright (C) 2017 <> (

Work in progress!


This is probably the most complete parser of X.509 certificates in python.

Code is in alpha stage! Don’t use for anything sensitive. I wrote it (based on previous work of colleagues) since there is no comprehensive python parser for X.509 certificates. Often python programmers had to parse openssl output.


  • I find it less painful to use than parsing output of ‘openssl x509’ somewhat stricter in extension parsing compared to openssl


  • It’s slow compared to openssl (about 2.3x compared to RHEL’s openssl-1.0-fips)
  • Currently not very strict in what string types in RDNs it accepts
  • API is still rather ugly and has no documentation yet; code is nasty at some places (and there’s some old dangling code like pkcs7/


  • pyasn1 >= 0.1.7


Install with pip:

pip install py3x509


LGPL v2 or later.

See LICENSE.txt.

Known bugs and quirks

  • Subject alternative name doesn’t show all subtypes, but ‘DNS’, ‘dirName’ and ‘email’ are supported.
  • Name constraints don’t distinguish among various GeneralName subtypes
  • Some extensions are not shown very nicely when put in string format
  • Not all extensions are supported
  • String types accepted for various RDN subelements are rather too permissive
  • RDN string conversion does not conform to RFC 4514
  • Badly formed extensions are ignored if not marked critical
    • easy to switch to more strict behavior
    • other clients do this as well; RFC 5280 specifies behavior for unknown elements in extensions in appendix B.1, but does not cover all cases (e.g. element exists, but with string type different from spec)


  • Cleanup: This module has it’s own pyasn1 models. Look if we can reuse the pyasn1_modules.rfc2459 X509 cert model.
  • Cleanup: Currently, the signature verifier does not work.

Project details

Release history Release notifications

This version


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for x509, version 0.1
Filename, size File type Python version Upload date Hashes
Filename, size x509-0.1.tar.gz (28.8 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page