Python Language Summit 2016: The Future Of The SSL Module

Presentation at Python Language Summit 2016 about Python's ssl stdlib module.

Transcript

1. The Future Of The SSL Module Python Language Summit 2016 Cory Benfield <cory@lukasa.co.uk> Christian Heimes <christian@python.org>
2. Cory Benfield ❏ hyper (HTTP/2 for Python) ❏ PyOpenSSL ❏ requests ❏ urllib3 ❏ Employed by Hewlett Packard Enterprise to work on HTTP and HTTP/2 in Python
3. Christian Heimes ❏ Python core contributor ❏ co-maintainer of Python’s ssl module ❏ employed by Red Hat to work on Identity Management and Public Key Infrastructure
4. Introduction
5. What is the SSL module ❏ provides TLS/SSL support for Python ❏ basic TLS server and client support ❏ no S/MIME or code signing ❏ uses OpenSSL internally ❏ vital for PIP to download packages for PyPI
6. Alternative packages ❏ PyOpenSSL (OpenSSL, based on PyCA cryptography) ❏ python-nss (Mozilla NSS, heavily used in Red Hat) ❏ python-gnutls (GnuTLS) ❏ QSslSocket (pyqt) ❏ javax.net.ssl (Jython) ❏ System.Security.Cryptography (IronPython) ❏ ...
7. SSL module is in a dire state
8. SSL module is in a bad state ❏ “naturally grown” over many years ❏ complicated ❏ _ssl._SSLSocket is wrapped by ssl.SSLObject, which is wrapped again by ssl.SSLSocket, which is a subclass of socket.socket. ❏ insane, footgunny legacy API ❏ SSLSocket.getpeercert() returns empty dict for CERT_NONE ❏ SSLContext() defaults to no verification, must use custom factory ❏ stdlib modules accept context or cert/key/verify args
9. Lack of features ❏ no validation callback ❏ no access to cert chain ❏ private keys can only be loaded from a file ❏ no memory buffer ❏ no PKCS#11 engine ❏ incomprehensible error messages when cert validation failed ❏ no SPKI hash for cert pinning (HPKP) ❏ no OCSP validation
10. and more ❏ no general-purpose API ❏ really a wrapper around OpenSSL ❏ written in C ❏ PyPy, Jython and IronPython have to roll their own implementation ❏ additional work ❏ additional bugs ❏ stuck to OpenSSL 0.9.8 features ❏ stuck to custom host name verification code
11. Recently it got a bit better
12. Improvements ❏ PEP 466 -- Network Security Enhancements for Python 2.7. x ❏ PEP 476 -- Enabling certificate verification ❏ backports to Python 2.7 ❏ ssl.create_default_context() Thanks to Alex, Antoine, Donald, Nick and whoever contributed to the cause!
13. The Future
14. Standardize context and ABCs for TLS ❏ deprecated cert/key/verification args ❏ push 3rd party libraries to use context argument ❏ ABC ❏ context.wrap_socket(socket, hostname) → SSLSocket ❏ SSLSocket ❏ SSL-specific exceptions ❏ creation and configuration of context object is not standardized
15. Add some new features ❏ SSLContext.set_verify_call() ❏ def verify(verifycontext, ok) -> bool ❏ X509 type ❏ instead of getpeercert() dict ❏ VerifyContext type (X509_STORE_CTX) ❏ current subject, issuer, error ❏ PrivateKey type ❏ OCSP staple verification ❏ PyCapsule export of internal C API ❏ allow 3rd party to interact with internal C API and OpenSSL objects
16. Feature moratorium ❏ SSL module should provide basic features for stdlib and PIP ❏ some new and security-relevant features ❏ push users to 3rd party software for advanced use cases ❏ PyOpenSSL ❏ cryptography.tls ?
17. Go OpenSSL 1.1.0 ❏ OpenSSL 1.1.0 made struct opaque and has cleaner API ❏ provide 1.0.2 compatibility layer (implemented in #26470) ❏ deprecate OpenSSL 1.0.1 and 0.9.8 ❏ use OpenSSL to verify host names ❏ backward compatibility? ❏ OSX? ❏ LibreSSL?
18. Root CA certificates (trust anchors) ❏ requests comes with certifi ❏ Python must never ever ship its own root certificate bundle. Period. ❏ Trust the operating system and use its root store. ❏ OSX? ❏ Windows implementation is semi-broken. SChannel fetch unknown root certs from MS, Python doesn’t. ❏ Libraries should provide SSLContext argument so users can customize trust settings or use env var SSL_CERT_FILE.
19. Thank you