service-identity
Service identity verification for pyOpenSSL & cryptography.
Decision gist · record as of 2026-08-14
Yes. This is a focused, well-maintained security library with no known vulnerabilities, low install friction, and permissive licensing. Install it if you're building TLS clients or servers with cryptography or pyOpenSSL and need robust hostname verification beyond basic SSL defaults. The recent removal of pyasn1 dependencies makes it lighter and more maintainable.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires cryptography 47.0.0 or later (or pyOpenSSL 26.1.0 with cryptography 47.0.0) as the package no longer depends on pyasn1.
- Low friction installation with only two runtime dependencies (attrs and cryptography).
- Actively maintained with recent releases; status is active and supports current Python versions from 3.8 through 3.15.
License · maintenance · safety
MIT (permissive) — MIT license is permissive; you can use this package freely in commercial and private projects with minimal restrictions.
last release 2026-05-30 (76 days)
0 known vulnerabilities (OSV.dev, 2026-08-14) · 16,467,631 downloads/mo, #1,151 on PyPI
Alternatives
Verify before relying
pip install service-identity
from service_identity import cryptography as si_crypto
# Verify a certificate against a hostname
si_crypto.verify_hostname(cert, hostname)- Exact API surface and available verification methods beyond hostname checking
- Performance characteristics when verifying large certificate batches
- Whether wildcard certificate handling covers all RFC 6125 edge cases beyond the single-label fix
What it is and what it does
service-identity is a certificate verification library that checks whether a cryptography or pyOpenSSL certificate is valid for a given hostname or IP address. It implements RFC 6125 fully, going beyond simple hostname matching to handle wildcards, alternative names, and other service identity verification scenarios. The package protects against man-in-the-middle attacks by ensuring certificates are actually issued for the services you're connecting to.
The library recently dropped its dependency on pyasn1 in favor of cryptography's native Rust-based ASN.1 decoder, simplifying its dependency tree. It works with modern Python versions (3.8 through 3.15) and is actively maintained. The package is particularly useful when building TLS clients or servers that need robust certificate validation beyond what basic SSL libraries provide.
Use it for
- Verify TLS certificates in custom HTTPS clients to prevent MITM attacks
- Validate certificates in pyOpenSSL-based applications before accepting connections
- Inspect certificate service identities to debug hostname mismatch errors
- Build secure reverse proxies or load balancers that validate upstream certificates
- Implement certificate validation logic in network services
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
This is a focused, well-maintained security library with no known vulnerabilities, low install friction, and permissive licensing. Install it if you're building TLS clients or servers with cryptography or pyOpenSSL and need robust hostname verification beyond basic SSL defaults. The recent removal of pyasn1 dependencies makes it lighter and more maintainable.
Install
service-identity on PyPI
Before you install
Low friction installation with only two runtime dependencies (attrs and cryptography). Actively maintained with recent releases; status is active and supports current Python versions from 3.8 through 3.15.
Requires cryptography 47.0.0 or later (or pyOpenSSL 26.1.0 with cryptography 47.0.0) as the package no longer depends on pyasn1.
License in practice
MIT license is permissive; you can use this package freely in commercial and private projects with minimal restrictions.
Quickstart
pip install service-identity
from service_identity import cryptography as si_crypto
# Verify a certificate against a hostname
si_crypto.verify_hostname(cert, hostname)Verify before relying
- Exact API surface and available verification methods beyond hostname checking
- Performance characteristics when verifying large certificate batches
- Whether wildcard certificate handling covers all RFC 6125 edge cases beyond the single-label fix
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 2 packagesattrscryptography |
| Maintenance | Actively maintained 76 days since the last release |
| First released | |
| Downloads | 16,467,631 / month, #1,151 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableLicense :: OSI Approved :: MIT LicenseOperating System :: OS IndependentProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.15Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: Security :: CryptographyTopic :: Software Development :: Libraries :: Python ModulesTyping :: Typed |
Evidence: service_identity-26.1.0-py3-none-any.whl
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See also backports.ssl_match_hostname · ndg-httpsclient · pyOpenSSL · openssl-ocsp-responder · pip-system-certs · types-pyOpenSSL · hstspreload · dkimpy · ocspresponder · srp