ACIL FM

Nama	Ukuran	Aksi
development	-	Open
hazmat	-	Open
x509	-	Open
_ext	-	Open
_static	-	Open
api-stability.rst	2.93 MB	View DL Edit
changelog.rst	30 B	View DL Edit
community.rst	589 B	View DL Edit
conf.py	6.17 MB	View DL Edit
doing-a-release.rst	3.71 MB	View DL Edit
exceptions.rst	853 B	View DL Edit
faq.rst	9.79 MB	View DL Edit
fernet.rst	11.33 MB	View DL Edit
glossary.rst	4.62 MB	View DL Edit
index.rst	2.64 MB	View DL Edit
installation.rst	11.71 MB	View DL Edit
limitations.rst	2.12 MB	View DL Edit
make.bat	4.99 MB	View DL Edit
Makefile	5.46 MB	View DL Edit
openssl.rst	4.6 MB	View DL Edit
random-numbers.rst	1.55 MB	View DL Edit
security.rst	3.51 MB	View DL Edit
spelling_wordlist.txt	1.22 MB	View DL Edit

Edit file: /usr/share/doc/python3-cryptography/docs/random-numbers.rst

Random number generation
========================

When generating random data for use in cryptographic operations, such as an
initialization vector for encryption in
:class:`~cryptography.hazmat.primitives.ciphers.modes.CBC` mode, you do not
want to use the standard :mod:`random` module APIs. This is because they do not
provide a cryptographically secure random number generator, which can result in
major security issues depending on the algorithms in use.

Therefore, it is our recommendation to `always use your operating system's
provided random number generator`_, which is available as :func:`os.urandom`.
For example, if you need 16 bytes of random data for an initialization vector,
you can obtain them with:

.. doctest::

>>> import os
    >>> iv = os.urandom(16)

This will use ``/dev/urandom`` on UNIX platforms, and ``CryptGenRandom`` on
Windows.

If you need your random number as an integer (for example, for
:meth:`~cryptography.x509.CertificateBuilder.serial_number`), you can use
``int.from_bytes`` to convert the result of ``os.urandom``:

.. code-block:: pycon

>>> serial = int.from_bytes(os.urandom(20), byteorder="big")

Starting with Python 3.6 the `standard library includes`_ the ``secrets``
module, which can be used for generating cryptographically secure random
numbers, with specific helpers for text-based formats.

.. _`always use your operating system's provided random number generator`: https://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers/
.. _`standard library includes`: https://docs.python.org/3/library/secrets.html

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