======================================================== pyOpenSSL -- A Python wrapper around the OpenSSL library

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Note: The Python Cryptographic Authority strongly suggests the use of pyca/cryptography_ where possible. If you are using pyOpenSSL for anything other than making a TLS connection you should move to cryptography and drop your pyOpenSSL dependency.

High-level wrapper around a subset of the OpenSSL library. Includes

• SSL.Connection objects, wrapping the methods of Python's portable sockets
• Callbacks written in Python
• Extensive error-handling mechanism, mirroring OpenSSL's error codes

... and much more.

You can find more information in the documentation_. Development takes place on GitHub_.

Discussion

If you run into bugs, you can file them in our issue tracker_.

We maintain a cryptography-dev_ mailing list for both user and development discussions.

You can also join #pyca on irc.libera.chat to ask questions or get involved.

.. _documentation: https://pyopenssl.org/ .. _issue tracker: https://github.com/pyca/pyopenssl/issues .. _cryptography-dev: https://mail.python.org/mailman/listinfo/cryptography-dev .. _GitHub: https://github.com/pyca/pyopenssl .. _pyca/cryptography: https://github.com/pyca/cryptography

Release Information

26.3.0 (2026-06-12)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Dropped support for Python 3.8.
• The minimum cryptography version is now 49.0.0.
• Removed deprecated OpenSSL.crypto.X509Req, OpenSSL.crypto.dump_certificate_request, and OpenSSL.crypto.load_certificate_request. cryptography.x509 should be used instead.
• OpenSSL.SSL.Connection.set_session now raises ValueError if the Session was obtained from a Connection that was using a different Context than this one. OpenSSL requires (but does not verify) that sessions only be re-used with a compatible SSL_CTX, so this contract is now enforced.

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.crypto.PKey.generate_key and OpenSSL.crypto.PKey.check. The key generation and loading APIs in cryptography should be used instead.
• Deprecated OpenSSL.crypto.dump_privatekey. The serialization APIs on cryptography private key types should be used instead.
• Deprecated all the mutable APIs on OpenSSL.crypto.X509: set_version, set_pubkey, sign, set_serial_number, gmtime_adj_notAfter, gmtime_adj_notBefore, set_notBefore, set_notAfter, set_issuer, and set_subject. cryptography.x509.CertificateBuilder should be used instead.
• Deprecated OpenSSL.SSL.Context.set_passwd_cb. Users should decrypt and load their private keys themselves, with cryptography's key loading APIs, and then call OpenSSL.SSL.Context.use_privatekey.
• Deprecated OpenSSL.crypto.X509Name, as well as the remaining APIs that consume or return it: OpenSSL.crypto.X509.get_issuer, OpenSSL.crypto.X509.get_subject, and OpenSSL.SSL.Context.set_client_ca_list. The APIs in cryptography.x509 should be used instead.

Changes: ^^^^^^^^

• OpenSSL.SSL.Connection.get_client_ca_list now takes an as_cryptography keyword-argument. When True is passed then cryptography.x509.Name are returned, instead of OpenSSL.crypto.X509Name. In the future, passing False (the default) will be deprecated.

26.2.0 (2026-05-04)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Removed deprecated OpenSSL.crypto.X509Extension, OpenSSL.crypto.X509Req.add_extension, OpenSSL.crypto.X509Req.get_extensions, OpenSSL.crypto.X509.add_extension, OpenSSL.crypto.X509.get_extensions. cryptography.x509 should be used instead.
• It is now an error to calling any mutating method on OpenSSL.SSL.Context after it has been used to create a Connection. This was previously deprecated and has always been unsafe.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Maximum supported cryptography version is now 48.x.
• Added OpenSSL.SSL.Connection.set_options to set options on a per-connection basis.

26.1.0 (2026-04-24)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Maximum supported cryptography version is now 47.x.
• Fixed X509Name field setters to correctly pass the value length to OpenSSL. Previously, values containing NUL bytes would be silently truncated, causing a divergence between the stored ASN.1 value and the value visible from Python. Credit to BudongJW for reporting the issue. CVE-2026-40475

26.0.0 (2026-03-15)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Dropped support for Python 3.7.
• The minimum cryptography version is now 46.0.0.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Added support for using aws-lc instead of OpenSSL.
• Properly raise an error if a DTLS cookie callback returned a cookie longer than DTLS1_COOKIE_LENGTH bytes. Previously this would result in a buffer-overflow. Credit to dark_haxor for reporting the issue. CVE-2026-27459
• Added OpenSSL.SSL.Connection.get_group_name to determine which group name was negotiated.
• Context.set_tlsext_servername_callback now handles exceptions raised in the callback by calling sys.excepthook and returning a fatal TLS alert. Previously, exceptions were silently swallowed and the handshake would proceed as if the callback had succeeded. Credit to Leury Castillo for reporting this issue. CVE-2026-27448

25.3.0 (2025-09-16)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Maximum supported cryptography version is now 46.x.

25.2.0 (2025-09-14)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• The minimum cryptography version is now 45.0.7.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• pyOpenSSL now sets SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER on connections by default, matching CPython's behavior.
• Added OpenSSL.SSL.Context.clear_mode.
• Added OpenSSL.SSL.Context.set_tls13_ciphersuites to set the allowed TLS 1.3 ciphers.
• Added OpenSSL.SSL.Connection.set_info_callback

25.1.0 (2025-05-17)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

• Attempting using any methods that mutate an OpenSSL.SSL.Context after it has been used to create an OpenSSL.SSL.Connection will emit a warning. In a future release, this will raise an exception.

Changes: ^^^^^^^^

• cryptography maximum version has been increased to 45.0.x.

25.0.0 (2025-01-12)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Corrected type annotations on Context.set_alpn_select_callback, Context.set_session_cache_mode, Context.set_options, Context.set_mode, X509.subject_name_hash, and X509Store.load_locations.
• Deprecated APIs are now marked using warnings.deprecated. mypy will emit deprecation notices for them when used with --enable-error-code deprecated.

24.3.0 (2024-11-27)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Removed the deprecated OpenSSL.crypto.CRL, OpenSSL.crypto.Revoked, OpenSSL.crypto.dump_crl, and OpenSSL.crypto.load_crl. cryptography.x509's CRL functionality should be used instead.
• Removed the deprecated OpenSSL.crypto.sign and OpenSSL.crypto.verify. cryptography.hazmat.primitives.asymmetric's signature APIs should be used instead.

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.rand - callers should use os.urandom() instead.
• Deprecated add_extensions and get_extensions on OpenSSL.crypto.X509Req and OpenSSL.crypto.X509. These should have been deprecated at the same time X509Extension was. Users should use pyca/cryptography's X.509 APIs instead.
• Deprecated OpenSSL.crypto.get_elliptic_curves and OpenSSL.crypto.get_elliptic_curve, as well as passing the reult of them to OpenSSL.SSL.Context.set_tmp_ecdh, users should instead pass curves from cryptography.
• Deprecated passing X509 objects to OpenSSL.SSL.Context.use_certificate, OpenSSL.SSL.Connection.use_certificate, OpenSSL.SSL.Context.add_extra_chain_cert, and OpenSSL.SSL.Context.add_client_ca, users should instead pass cryptography.x509.Certificate instances. This is in preparation for deprecating pyOpenSSL's X509 entirely.
• Deprecated passing PKey objects to OpenSSL.SSL.Context.use_privatekey and OpenSSL.SSL.Connection.use_privatekey, users should instead pass cryptography private key instances. This is in preparation for deprecating pyOpenSSL's PKey entirely.

Changes: ^^^^^^^^

• cryptography maximum version has been increased to 44.0.x.
• OpenSSL.SSL.Connection.get_certificate, OpenSSL.SSL.Connection.get_peer_certificate, OpenSSL.SSL.Connection.get_peer_cert_chain, and OpenSSL.SSL.Connection.get_verified_chain now take an as_cryptography keyword-argument. When True is passed then cryptography.x509.Certificate are returned, instead of OpenSSL.crypto.X509. In the future, passing False (the default) will be deprecated.

24.2.1 (2024-07-20)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Fixed changelog to remove sphinx specific restructured text strings.

24.2.0 (2024-07-20)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.crypto.X509Req, OpenSSL.crypto.load_certificate_request, OpenSSL.crypto.dump_certificate_request. Instead, cryptography.x509.CertificateSigningRequest, cryptography.x509.CertificateSigningRequestBuilder, cryptography.x509.load_der_x509_csr, or cryptography.x509.load_pem_x509_csr should be used.

Changes: ^^^^^^^^

• Added type hints for the SSL module. #1308 <https://github.com/pyca/pyopenssl/pull/1308>_.
• Changed OpenSSL.crypto.PKey.from_cryptography_key to accept public and private EC, ED25519, ED448 keys. #1310 <https://github.com/pyca/pyopenssl/pull/1310>_.

24.1.0 (2024-03-09)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Removed the deprecated OpenSSL.crypto.PKCS12 and OpenSSL.crypto.NetscapeSPKI. OpenSSL.crypto.PKCS12 may be replaced by the PKCS#12 APIs in the cryptography package.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

24.0.0 (2024-01-22)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Added OpenSSL.SSL.Connection.get_selected_srtp_profile to determine which SRTP profile was negotiated. #1279 <https://github.com/pyca/pyopenssl/pull/1279>_.

23.3.0 (2023-10-25)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Dropped support for Python 3.6.
• The minimum cryptography version is now 41.0.5.
• Removed OpenSSL.crypto.load_pkcs7 and OpenSSL.crypto.load_pkcs12 which had been deprecated for 3 years.
• Added OpenSSL.SSL.OP_LEGACY_SERVER_CONNECT to allow legacy insecure renegotiation between OpenSSL and unpatched servers. #1234 <https://github.com/pyca/pyopenssl/pull/1234>_.

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.crypto.PKCS12 (which was intended to have been deprecated at the same time as OpenSSL.crypto.load_pkcs12).
• Deprecated OpenSSL.crypto.NetscapeSPKI.
• Deprecated OpenSSL.crypto.CRL
• Deprecated OpenSSL.crypto.Revoked
• Deprecated OpenSSL.crypto.load_crl and OpenSSL.crypto.dump_crl
• Deprecated OpenSSL.crypto.sign and OpenSSL.crypto.verify
• Deprecated OpenSSL.crypto.X509Extension

Changes: ^^^^^^^^

• Changed OpenSSL.crypto.X509Store.add_crl to also accept cryptography's x509.CertificateRevocationList arguments in addition to the now deprecated OpenSSL.crypto.CRL arguments.
• Fixed test_set_default_verify_paths test so that it is skipped if no network connection is available.

23.2.0 (2023-05-30)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Removed X509StoreFlags.NOTIFY_POLICY. #1213 <https://github.com/pyca/pyopenssl/pull/1213>_.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• cryptography maximum version has been increased to 41.0.x.
• Invalid versions are now rejected in OpenSSL.crypto.X509Req.set_version.
• Added X509VerificationCodes to OpenSSL.SSL. #1202 <https://github.com/pyca/pyopenssl/pull/1202>_.

23.1.1 (2023-03-28)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Worked around an issue in OpenSSL 3.1.0 which caused X509Extension.get_short_name to raise an exception when no short name was known to OpenSSL. #1204 <https://github.com/pyca/pyopenssl/pull/1204>_.

23.1.0 (2023-03-24)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• cryptography maximum version has been increased to 40.0.x.
• Add OpenSSL.SSL.Connection.DTLSv1_get_timeout and OpenSSL.SSL.Connection.DTLSv1_handle_timeout to support DTLS timeouts #1180 <https://github.com/pyca/pyopenssl/pull/1180>_.

23.0.0 (2023-01-01)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Add OpenSSL.SSL.X509StoreFlags.PARTIAL_CHAIN constant to allow for users to perform certificate verification on partial certificate chains. #1166 <https://github.com/pyca/pyopenssl/pull/1166>_
• cryptography maximum version has been increased to 39.0.x.

22.1.0 (2022-09-25)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Remove support for SSLv2 and SSLv3.
• The minimum cryptography version is now 38.0.x (and we now pin releases against cryptography major versions to prevent future breakage)
• The OpenSSL.crypto.X509StoreContextError exception has been refactored, changing its internal attributes. #1133 <https://github.com/pyca/pyopenssl/pull/1133>_

Deprecations: ^^^^^^^^^^^^^

• OpenSSL.SSL.SSLeay_version is deprecated in favor of OpenSSL.SSL.OpenSSL_version. The constants OpenSSL.SSL.SSLEAY_* are deprecated in favor of OpenSSL.SSL.OPENSSL_*.

Changes: ^^^^^^^^

• Add OpenSSL.SSL.Connection.set_verify and OpenSSL.SSL.Connection.get_verify_mode to override the context object's verification flags. #1073 <https://github.com/pyca/pyopenssl/pull/1073>_
• Add OpenSSL.SSL.Connection.use_certificate and OpenSSL.SSL.Connection.use_privatekey to set a certificate per connection (and not just per context) #1121 <https://github.com/pyca/pyopenssl/pull/1121>_.

22.0.0 (2022-01-29)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Drop support for Python 2.7. #1047 <https://github.com/pyca/pyopenssl/pull/1047>_
• The minimum cryptography version is now 35.0.

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Expose wrappers for some DTLS <https://en.wikipedia.org/wiki/Datagram_Transport_Layer_Security>_ primitives. #1026 <https://github.com/pyca/pyopenssl/pull/1026>_

21.0.0 (2021-09-28)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• The minimum cryptography version is now 3.3.
• Drop support for Python 3.5

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Raise an error when an invalid ALPN value is set. #993 <https://github.com/pyca/pyopenssl/pull/993>_
• Added OpenSSL.SSL.Context.set_min_proto_version and OpenSSL.SSL.Context.set_max_proto_version to set the minimum and maximum supported TLS version #985 <https://github.com/pyca/pyopenssl/pull/985>_.
• Updated to_cryptography and from_cryptography methods to support an upcoming release of cryptography without raising deprecation warnings. #1030 <https://github.com/pyca/pyopenssl/pull/1030>_

20.0.1 (2020-12-15)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Deprecations: ^^^^^^^^^^^^^

Changes: ^^^^^^^^

• Fixed compatibility with OpenSSL 1.1.0.

20.0.0 (2020-11-27)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• The minimum cryptography version is now 3.2.
• Remove deprecated OpenSSL.tsafe module.
• Removed deprecated OpenSSL.SSL.Context.set_npn_advertise_callback, OpenSSL.SSL.Context.set_npn_select_callback, and OpenSSL.SSL.Connection.get_next_proto_negotiated.
• Drop support for Python 3.4
• Drop support for OpenSSL 1.0.1 and 1.0.2

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.crypto.load_pkcs7 and OpenSSL.crypto.load_pkcs12.

Changes: ^^^^^^^^

• Added a new optional chain parameter to OpenSSL.crypto.X509StoreContext() where additional untrusted certificates can be specified to help chain building. #948 <https://github.com/pyca/pyopenssl/pull/948>_
• Added OpenSSL.crypto.X509Store.load_locations to set trusted certificate file bundles and/or directories for verification. #943 <https://github.com/pyca/pyopenssl/pull/943>_
• Added Context.set_keylog_callback to log key material. #910 <https://github.com/pyca/pyopenssl/pull/910>_
• Added OpenSSL.SSL.Connection.get_verified_chain to retrieve the verified certificate chain of the peer. #894 <https://github.com/pyca/pyopenssl/pull/894>_.
• Make verification callback optional in Context.set_verify. If omitted, OpenSSL's default verification is used. #933 <https://github.com/pyca/pyopenssl/pull/933>_
• Fixed a bug that could truncate or cause a zero-length key error due to a null byte in private key passphrase in OpenSSL.crypto.load_privatekey and OpenSSL.crypto.dump_privatekey. #947 <https://github.com/pyca/pyopenssl/pull/947>_

19.1.0 (2019-11-18)

Backward-incompatible changes: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

• Removed deprecated ContextType, ConnectionType, PKeyType, X509NameType, X509ReqType, X509Type, X509StoreType, CRLType, PKCS7Type, PKCS12Type, and NetscapeSPKIType aliases. Use the classes without the Type suffix instead. #814 <https://github.com/pyca/pyopenssl/pull/814>_
• The minimum cryptography version is now 2.8 due to issues on macOS with a transitive dependency. #875 <https://github.com/pyca/pyopenssl/pull/875>_

Deprecations: ^^^^^^^^^^^^^

• Deprecated OpenSSL.SSL.Context.set_npn_advertise_callback, OpenSSL.SSL.Context.set_npn_select_callback, and OpenSSL.SSL.Connection.get_next_proto_negotiated. ALPN should be used instead. #820 <https://github.com/pyca/pyopenssl/pull/820>_

Changes: ^^^^^^^^

• Support bytearray in SSL.Connection.send() by using cffi's from_buffer. #852 <https://github.com/pyca/pyopenssl/pull/852>_
• The OpenSSL.SSL.Context.set_alpn_select_callback can return a new NO_OVERLAPPING_PROTOCOLS sentinel value to allow a TLS handshake to complete without an application protocol.

Full changelog <https://pyopenssl.org/en/stable/changelog.html>_.