All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Calendar Versioning.

The first number of the version is the year. The second number is incremented with each release, starting at 1 for each year. The third number is for emergencies when we need to start branches for older releases.

You can find out backwards-compatibility policy here.

24.1.0 - 2024-01-14#


  • If a certificate doesn’t contain any subjectAltNames, we now raise service_identity.CertificateError instead of service_identity.VerificationError to make the problem easier to debug. #67

23.1.0 - 2023-06-14#


  • All Python versions up to and including 3.7 have been dropped.

  • Support for commonName in certificates has been dropped. It has been deprecated since 2017 and isn’t supported by any major browser.

  • The oldest supported pyOpenSSL version (when using the pyopenssl backend) is now 17.0.0. When using such an old pyOpenSSL version, you have to pin cryptography yourself to ensure compatibility between them. Please check out constraints/oldest-pyopenssl.txt to verify what we are testing against.


  • If you’ve used service_identity.(cryptography|pyopenssl).extract_ids(), please switch to the new names extract_patterns(). #56


  • service_identity.(cryptography|pyopenssl).extract_patterns() are now public APIs (FKA extract_ids()). You can use them to extract the patterns from a certificate without verifying anything. #55

  • service-identity is now fully typed. #57

21.1.0 - 2021-05-09#


  • Python 3.4 is not supported anymore. It has been unsupported by the Python core team for a while now, its PyPI downloads are negligible, and our CI provider removed it as a supported option.

    It’s very unlikely that service-identity will break under 3.4 anytime soon, which is why we do not block its installation on Python 3.4. But we don’t test it anymore and will block it once someone reports breakage.


  • service_identity.exceptions.VerificationError can now be pickled and is overall more well-behaved as an exception. This raises the requirement of attrs to 19.1.0.

18.1.0 - 2018-12-05#


  • pyOpenSSL is optional now if you use service_identity.cryptography.* only.

  • Added support for iPAddress subjectAltNames. You can now verify whether a connection or a certificate is valid for an IP address using service_identity.pyopenssl.verify_ip_address() and service_identity.cryptography.verify_certificate_ip_address(). #12

17.0.0 - 2017-05-23#


  • Since Chrome 58 and Firefox 48 both don’t accept certificates that contain only a Common Name, its usage is hereby deprecated in service-identity too. We have been raising a warning since 16.0.0 and the support will be removed in mid-2018 for good.


  • When service_identity.SubjectAltNameWarning is raised, the Common Name of the certificate is now included in the warning message. #17

  • Added cryptography.x509 backend for verifying certificates. #18


  • Wildcards (*) are now only allowed if they are the leftmost label in a certificate. This is common practice by all major browsers. #19

16.0.0 - 2016-02-18#


  • Python 3.3 and 2.6 aren’t supported anymore. They may work by chance but any effort to keep them working has ceased.

    The last Python 2.6 release was on October 29, 2013 and isn’t supported by the CPython core team anymore. Major Python packages like Django and Twisted dropped Python 2.6 a while ago already.

    Python 3.3 never had a significant user base and wasn’t part of any distribution’s LTS release.

  • pyOpenSSL versions older than 0.14 are not tested anymore. They don’t even build on recent OpenSSL versions. Please note that its support may break without further notice.


  • Officially support Python 3.5.

  • A __str__ method to VerificationError.


  • service_identity.SubjectAltNameWarning is now raised if the server certificate lacks a proper SubjectAltName. #9

  • Port from characteristic to its spiritual successor attrs.

14.0.0 - 2014-08-22#


  • Switch to year-based version numbers.

  • Port to characteristic 14.0 (get rid of deprecation warnings).

  • Package docs with source distributions.

1.0.0 - 2014-06-15#


  • Drop support for Python 3.2. There is no justification to add complexity and unnecessary function calls for a Python version that nobody uses.



  • idna 0.6 did some backward-incompatible fixes that broke Python 3 support. This has been fixed now therefore service-identity only works with idna 0.6 and later. Unfortunately since idna doesn’t offer version introspection, service-identity can’t warn about it.

0.2.0 - 2014-04-06#


  • Official support for Python 3.4.


  • Refactor into a multi-module package. Most notably, verify_hostname and extract_ids live in the service_identity.pyopenssl module now.

  • verify_hostname now takes an OpenSSL.SSL.Connection for the first argument.

  • More strict checks for URI_IDs.


  • Less false positives in IP address detection.

0.1.0 - 2014-03-03#

Initial release.