py-purecrypt

A pure Python implementation of the crypt(3) function provided in the GNU C library (glibc). This implementation supports the MD5, SHA256, and SHA512 variants.

This package provides a drop-in replacement for the deprecated (and soon to be removed) crypt package provided in the Python standard library.

Because this is written in pure Python and depends only on the cryptography package, it should run on any platform supported by Python.

This implementation is not fast. If you're looking for speed, I suggest you consider alternatives such as bcrypt.

Installation

Install py-purecrypt from PyPI using pip or your preferred Python package manager.

Usage

This section shows basic usage examples.

Using the Compatibility API

You can use this package as a drop-in replacement for the deprecated crypt package that will soon be removed from the Python standard library. At present this package supports only the MD5, SHA256, and SHA512 methods.

Example

import purecrypt as crypt

plaintext_pw = "Hello world!"
salt = crypt.mksalt(crypt.METHOD_SHA256, rounds=10000)
hashed_pw = crypt.crypt(plaintext_pw, salt)

Using the Native API

Encrypt a password

Choose a method and generate a salt, then encrypt.

from purecrypt import Crypt, Method

plaintext_password = "super secret"
salt = Crypt.generate_salt(Method.SHA512)
ciphertext_password = Crypt.encrypt(plaintext_password, salt)

When generating a salt you can specify the number of rounds to perform while encrypting.

from purecrypt import Crypt, Method

plaintext_password = "super secret"
salt = Crypt.generate_salt(Method.SHA256, rounds=10000)
ciphertext_password = Crypt.encrypt(plaintext_password, salt)

Validate a password

To validate a given password, you just need the ciphertext that was produced when the original password was encrypted.

from purecrypt import Crypt

# as produced by the previous example
ciphertext_password = "$5$rounds=10000$vGuBkkhnTmd9BHeFpw4vxHNHJ1bxFRZX$2xiip3lO0cjGg3tZMdled9LpChHk1nmpF6hU6ZW05W1"

plaintext_password = "super secret"
assert Crypt.is_valid(plaintext_password, ciphertext_password)