StateofcryptoinPython A library created by people who make poor life choices.
WhatDoWeWant
Algorithm support Open Source MAINTAINED & Tested Python Support
Trust
WHyc? All major cryptographic libraries are currently implemented in a low level language, mostly C or C++.
Reviewed Code Several C libraries have been sponsored through the review process for professional crypto review including various compliances that some customers care about.
Future possibilities There are some exciting options for future work in the crypto space with languages like Rust / Go. Unfortunately, these aren’t usable from Python right now.
Timing / Memory Attacks These attacks relate to exploiting timing differentials or securely wiping memory. They are difficult or impossible to remediate without the low level control exposed by C.
Existing Code Writing good crypto code is hard. Most existing libraries have a long history including significant bug-fixing / research.
StateofC OSS X-Platform Maintained Ubiquitous Std. Algorithms FIPS
OpenSSL
NSS
NaCl
Botan
CommonCrypto
MS CSP
Libgcrypt
StateOfPython Backend Maintained Python Support Reviewed Completeness
m2crypto openssl recently active pypy with patch, no py3 no openssl swig
pycrypto bespoke low no pypy no no AEAD (without alpha)
pyopenssl openssl* yes yes (with crypto) no Thin openssl bindings
python-nss NSS low unknown no exposes most of NSS
botan botan yes py3, maybe pypy no exposes most of botan
Most of these libraries require / assume the user understands how to use the underlying C library correctly.
Do we need another Python library?
Why a new crypto library for Python?
• Lack of maintenance. • Use of poor implementations
of algorithms (i.e. ones with known side-channel attacks).
• Lack of high level, “Cryptography for humans”, APIs.
• Absence of algorithms such as AES-GCM and HKDF.
• Poor introspectability, and thus poor testability.
• Extremely error prone APIs, and bad defaults.
• Lack of PyPy and Python 3 support.
Introducing
cryptography
Grandiose Vision:
A cryptographic standard library for Python.
ourPeople
Alex Gaynor (Alex_gaynor) Paul Kehrer (reaperhulk) David Reid (dreid) Alex Stapleton (alexs)
Aryx, Jarret Raim (jraim), Donald Stufft (dstufft), cyli, Mohammed Attia (skeuomorf), Jean-Paul Calderone (exarkun), Hynek Schlawack (hynek), Julian Krause (juliankrause), Richard Wall (wallrj), Matt Iverson (lvoz),
Chris Glass (chrisglass), Laurens Van Houtven (lvh), Konstantinos Koukopoulos (kouk), koobs, Christian Heimes (tiran), fedor-brunner, Kyle Kelley (rgbkrk), jgiannuzzi, manuels, Wouter Bolsterlee (wbolster), Arturo Filasto (hellais), Stephen Holsapple (sholsapp), Marcin Wielgoszewski (mwielgoszewshi), Jay Parlar (parlarjb)
TheStructure
Bindings
Hazmat
Recipes
Backends
OpenSSL Our primary (and only guaranteed) backend. We don’t currently package OpenSSL to allow for flexibility for package maintainers.
Common Crypto Available on OS X and iOS, this is the preferred backend on OS X. Apple has decided not to ship newer version of OpenSSL, leaving developers with a old version lacking modern algorithms.
Cryptography is designed around the concept of backends. Each backend implements a set of defined interfaces. This allows us to implement a backend for each C library and exchange them transparently.
MULTIBACKEND This meta-backend allows composition and prioritization of multiple backends. This creates a superset of operations in Python, isolating the developer from variations in C libraries.
Moar! Any C backend can be included. We have spoken with many of the C library maintainers about writing a backend for cryptography.
Tests per run
Testify 66,144
500+ Million tests per week
77 Runs per build
5,093,088 Tests per build
15 Builds per day
45 Documentation runs per day
currentSupport Symmetric Currently support a variety of common ciphers such as AES, Camellia, 3DES, CAST5, etc. Most non-patent encumbered block cipher modes are also supported.
HMAC HMAC using any supported hash algorithm. Supports constant time verification.
Key Derivation Functions PBKDF2HMAC, HKDF
One Time Password TOTP, HOTP
RSA SIGNING AND VERIFICATION Supports PKCS#1 v1.5 padding and Probabilistic Signature Scheme (using MGF1 with user-definable hash)
fernet A high level recipe designed to provide easy to use authenticated encryption.
??? Any C backend can be included. We have had preliminary talks with various maintainers about moving into cryptography and PyOpenSSL 0.14+ depends on our project.
LetsReview
Algorithm support Open Source MAINTAINED & Tested Python Support
Multi-Backend
& Openssl
Apache 2 500+ Million Tests
30+ contributors
2.6, 2.7, 3.2, 3.3, 3.4,
& pypy
FutureWork DSA signing/verification Defaulting to deterministic k
Asymmetric Key loading PKCS1, PKCS8, JWK
RSA Encryption/Decryption PKCS1 v1.5, OAEP
X509/TLS? Proper hostname validation, TLS 1.2, modern ciphersuites
Less Common Symmetric Primitives Chacha20, Salsa20
Github github.com/pyca/cryptography
Website
cryptography.io
Install
pip install cryptography
~ fin ~
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