index : cloud-email/cryptography	master
	python cryptography	James

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path: root/docs/development/custom-vectors/secp256k1

	Commit message (Expand)	Author	Age	Files	Lines
*	use the non-deprecated name for this function	Alex Gaynor	2015-12-19	1	-2/+2
*	Verification script	Alex Stapleton	2015-05-03	1	-0/+59
*	Script for generating SECP256K1 vectors	Alex Stapleton	2015-05-03	1	-0/+89

generated by cgit v1.2.3 (git 2.25.1) at 2025-09-15 02:25:37 +0000

.. hazmat::

Two-factor authentication
=========================

.. currentmodule:: cryptography.hazmat.primitives.twofactor

This module contains algorithms related to two-factor authentication.

Currently, it contains an algorithm for generating and verifying
one time password values based on Hash-based message authentication
codes (HMAC).

.. class:: InvalidToken

    This is raised when the verify method of a one time password function's
    computed token does not match the expected token.

.. currentmodule:: cryptography.hazmat.primitives.twofactor.hotp

.. class:: HOTP(key, length, algorithm, backend, enforce_key_length=True)

    .. versionadded:: 0.3

    HOTP objects take a ``key``, ``length`` and ``algorithm`` parameter. The
    ``key`` should be :doc:`randomly generated bytes </random-numbers>` and is
    recommended to be 160 :term:`bits` in length. The ``length`` parameter
    controls the length of the generated one time password and must be >= 6
    and <= 8.

    This is an implementation of :rfc:`4226`.

    .. doctest::

        >>> import os
        >>> from cryptography.hazmat.backends import default_backend
        >>> from cryptography.hazmat.primitives.twofactor.hotp import HOTP
        >>> from cryptography.hazmat.primitives.hashes import SHA1
        >>> key = os.urandom(20)
        >>> hotp = HOTP(key, 6, SHA1(), backend=default_backend())
        >>> hotp_value = hotp.generate(0)
        >>> hotp.verify(hotp_value, 0)

    :param bytes key: Per-user secret key. This value must be kept secret
                      and be at least 128 :term:`bits`. It is recommended that
                      the key be 160 bits.
    :param int length: Length of generated one time password as ``int``.
    :param cryptography.hazmat.primitives.hashes.HashAlgorithm algorithm: A
        :class:`~cryptography.hazmat.primitives.hashes`