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 ~