The django_otp package contains a framework for processing one-time passwords as well as support for :ref:`several types <built-in-plugins>` of OTP devices. Support for additional devices is handled by plugins, :ref:`distributed separately <other-plugins>`.
Adding two-factor authentication to your Django site involves four main tasks:
- Installing the django-otp plugins you want to use.
- Adding one or more OTP-enabled login views.
- Restricting access to all or portions of your site based on whether users have been verified by a registered OTP device.
- Providing mechanisms to register OTP devices to user accounts (or relying on the Django admin interface).
Basic installation has only two steps:
- Install :mod:`django_otp` and any :ref:`plugins <built-in-plugins>` that you'd like to use. These are simply Django apps to be installed in the usual way.
- Add :class:`django_otp.middleware.OTPMiddleware` to :setting:`MIDDLEWARE`. It must be installed after :class:`~django.contrib.auth.middleware.AuthenticationMiddleware`.
For example:
INSTALLED_APPS = [
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.admin',
'django.contrib.admindocs',
'django_otp',
'django_otp.plugins.otp_totp',
'django_otp.plugins.otp_hotp',
'django_otp.plugins.otp_static',
]
MIDDLEWARE = [
'django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django_otp.middleware.OTPMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
]
The plugins contain models that must be migrated.
Version 0.2.4 of django-otp introduced a South migration to the otp_totp plugin. Version 0.3.0 added Django 1.7 and South migrations to all apps. Care must be taken when upgrading in certain cases.
The recommended procedure is:
- Upgrade django-otp to 0.2.7, as described below.
- Upgrade Django to 1.7 or later.
- Upgrade django-otp to the latest version.
django-otp 0.4 dropped support for Django < 1.7.
If you're using django-otp <= 0.2.3, you need to convert otp_totp to South before going any further:
pip install 'django-otp==0.2.7' python manage.py migrate otp_totp 0001 --fake python manage.py migrate otp_totp
If you're not using South, you can run python manage.py sql otp_totp to see
the definition of the new last_t field and then construct a suitable ALTER
TABLE SQL statement for your database.
Once you've upgraded django-otp to version 0.2.4 or later (up to 0.2.7), it's safe to switch to Django 1.7 or later. You should not have South installed at this point, so any old migrations will simply be ignored.
Once on Django 1.7+, it's safe to upgrade django-otp to 0.3 or later. All plugins with models have Django migrations, which will be ignored if the tables have already been created.
If you're already on django-otp 0.3 or later when you move to Django 1.7+ (see below), you'll want to make sure Django knows that all migrations have already been run:
python manage.py migrate --fake <otp_plugin> ...
If you want to upgrade django-otp to 0.3.x under South, you'll need to convert all of the remaining plugins. First make sure you're running South 1.0, as earlier versions will not find the migrations. Then convert any plugin that you have installed:
pip install 'django-otp>=0.3' python manage.py migrate otp_hotp 0001 --fake python manage.py migrate otp_static 0001 --fake python manage.py migrate otp_yubikey 0001 --fake python manage.py migrate otp_twilio 0001 --fake
In a normal Django deployment, the user associated with a request is either authenticated or not. With the introduction of two-factor authentication, the situation becomes a little more complicated: while it is certainly possible to design a site such that two factors are required for any authentication, that's only one option. It's entirely reasonable to allow users to log in with either one or two factors and grant then access accordingly.
In this documentation, a user that has passed Django's authentication API is called :term:`authenticated`. A user that has additionally been accepted by a registered OTP device is called :term:`verified`. On an OTP-enabled Django site, there are thus three levels of authentication:
- anonymous
- authenticated
- authenticated + verified
When planning your site, you'll want to consider whether different views will require different levels of authentication. As a convenience, we provide the decorator :func:`django_otp.decorators.otp_required`, which is analogous to :func:`~django.contrib.auth.decorators.login_required`, but requires the user to be both authenticated and verified.
:class:`~django_otp.middleware.OTPMiddleware` populates
request.user.otp_device to the OTP device object that verified the current
user (if any). As a convenience, it also adds user.is_verified() as a
counterpart to user.is_authenticated(). It is not possible for a user to be
verified without also being authenticated. [1]
A django-otp plugin is simply a Django app that contains one or more models that are subclassed from :class:`django_otp.models.Device`. Each model class supports a single type of OTP device. Remember that when we use the term :term:`device` in this context, we're not necessarily referring to a physical device. At the code level, a device is a model object that can verify a particular type of OTP. For example, you might have a YubiKey that supports both the Yubico OTP algorithm and the HOTP standard: these would be represented as different devices and likely served by different plugins. A device that delivered HOTP values to a user by SMS would be a third device defined by another plugin.
OTP plugins are distributed as Django apps; to install a plugin, just add it to :setting:`INSTALLED_APPS` like any other. The order can be significant: any time we enumerate a user's devices, such as when we ask the user which device they would like to authenticate with, we will present them according to the order in which the apps are installed.
OTP devices come in two general flavors: passive and interactive. A passive device is one that can accept a token from the user and verify it with no preparation. Examples include devices corresponding to dedicated hardware or smartphone apps that generate sequenced or time-based tokens. An interactive device needs to communicate something to the user before it can accept a token. Two common types are devices that use a challenge-response OTP algorithm and devices that deliver a token to the user through an independent channel, such as SMS.
Internally, device instances can be flagged as confirmed or unconfirmed. By default, devices are confirmed as soon as they are created, but a plugin or deployment that wishes to include a confirmation step can mark a device unconfirmed initially. Unconfirmed devices will be ignored by the high-level OTP APIs.
django-otp includes support for several standard device types. :class:`~django_otp.plugins.otp_hotp.models.HOTPDevice` and :class:`~django_otp.plugins.otp_totp.models.TOTPDevice` handle standard OTP algorithms, which can be used with a variety of OTP generators. For example, it's easy to pair these devices with Google Authenticator using the otpauth URL scheme. If you have either the segno or qrcode packages installed, the admin interface will generate QR Codes for you.
HOTP is an algorithm that generates a pseudo-random sequence of codes based on an incrementing counter. Every time a prover generates a new code or a verifier verifies one, they increment their respective counters. This algorithm will fail if the prover generates too many codes without a successful verification.
If there is a failed attempt, this plugin will enforce an exponentially increasing delay before allowing verification to succeed (see :setting:`OTP_HOTP_THROTTLE_FACTOR`). The :meth:`~django_otp.models.Device.verify_token` method automatically applies this policy. For a better user experience, before calling :meth:`~django_otp.models.Device.verify_token` check whether verification is disabled by calling the :meth:`~django_otp.models.Device.verify_is_allowed` method.
.. module:: django_otp.plugins.otp_hotp
.. automodule:: django_otp.plugins.otp_hotp.models
:members:
.. autoclass:: django_otp.plugins.otp_hotp.admin.HOTPDeviceAdmin
.. setting:: OTP_HOTP_ISSUER
OTP_HOTP_ISSUER
Default: None
The issuer parameter for the otpauth URL generated by
:attr:`~django_otp.plugins.otp_hotp.models.HOTPDevice.config_url`.
This can be a string or a callable to dynamically set the value.
.. setting:: OTP_HOTP_THROTTLE_FACTOR
OTP_HOTP_THROTTLE_FACTOR
Default: 1
This controls the rate of throttling. The sequence of 1, 2, 4, 8... seconds is
multiplied by this factor to define the delay imposed after 1, 2, 3, 4...
successive failures. Set to 0 to disable throttling completely.
TOTP is an algorithm that generates a pseudo-random sequence of codes based on the current time. A typical implementation will change codes every 30 seconds, although this is configurable. This algorithm will fail if the prover and verifier have clocks that drift too far apart.
If there is a failed attempt, this plugin will enforce an exponentially increasing delay before allowing verification to succeed (see :setting:`OTP_TOTP_THROTTLE_FACTOR`). The :meth:`~django_otp.models.Device.verify_token` method automatically applies this policy. For a better user experience, before calling :meth:`~django_otp.models.Device.verify_token` check whether verification is disabled by calling the :meth:`~django_otp.models.Device.verify_is_allowed` method.
.. module:: django_otp.plugins.otp_totp
.. automodule:: django_otp.plugins.otp_totp.models
:members:
.. autoclass:: django_otp.plugins.otp_totp.admin.TOTPDeviceAdmin
.. setting:: OTP_TOTP_ISSUER
OTP_TOTP_ISSUER
Default: None
The issuer parameter for the otpauth URL generated by
:attr:`~django_otp.plugins.otp_totp.models.TOTPDevice.config_url`.
This can be a string or a callable to dynamically set the value.
.. setting:: OTP_TOTP_IMAGE
OTP_TOTP_IMAGE
Default: None
The image parameter for the otpauth URL generated by
:attr:`~django_otp.plugins.otp_totp.models.TOTPDevice.config_url`.
It should be a HTTPS URL pointing to a square PNG image.
This will be read and displayed by some authenticator applications, e.g. FreeOTP.
This can be a string or a callable to dynamically set the value.
.. setting:: OTP_TOTP_SYNC
OTP_TOTP_SYNC
Default: True
If true, then TOTP devices will keep track of the difference between the prover's clock and our own. Any time a :class:`~django_otp.plugins.otp_totp.models.TOTPDevice` matches a token in the past or future, it will update :attr:`~django_otp.plugins.otp_totp.models.TOTPDevice.drift` to the number of time steps that the two sides are out of sync. For subsequent tokens, we'll slide the window of acceptable tokens by this number.
.. setting:: OTP_TOTP_THROTTLE_FACTOR
OTP_TOTP_THROTTLE_FACTOR
Default: 1
This controls the rate of throttling. The sequence of 1, 2, 4, 8... seconds is
multiplied by this factor to define the delay imposed after 1, 2, 3, 4...
successive failures. Set to 0 to disable throttling completely.
.. module:: django_otp.plugins.otp_static
.. automodule:: django_otp.plugins.otp_static.models
:members: StaticDevice, StaticToken
.. autoclass:: django_otp.plugins.otp_static.admin.StaticDeviceAdmin
.. setting:: OTP_STATIC_THROTTLE_FACTOR
OTP_STATIC_THROTTLE_FACTOR
Default: 1
This controls the rate of throttling. The sequence of 1, 2, 4, 8… seconds is multiplied by this factor to define the delay imposed after 1, 2, 3, 4… successive failures. Set to 0 to disable throttling completely.
The static plugin also includes a management command called addstatictoken,
which will add a single static token to any account. This is useful for
bootstrapping and emergency access. Run manage.py addstatictoken -h for
details.
.. module:: django_otp.plugins.otp_email
.. automodule:: django_otp.plugins.otp_email.models :members: EmailDevice
.. autoclass:: django_otp.plugins.otp_email.admin.EmailDeviceAdmin
.. setting:: OTP_EMAIL_SENDER
OTP_EMAIL_SENDER
Default: None
The email address to use as the sender when we deliver tokens. If not set, this will automatically use :setting:`DEFAULT_FROM_EMAIL`.
.. setting:: OTP_EMAIL_SUBJECT
OTP_EMAIL_SUBJECT
Default: 'OTP token'
The subject of the email. You probably want to customize this.
.. setting:: OTP_EMAIL_BODY_TEMPLATE
OTP_EMAIL_BODY_TEMPLATE
Default: None
A raw template string to use for the email body. The render context will
include the generated token in the token key. Additional template context
may be passed to
:meth:`~django_otp.plugins.otp_email.models.EmailDevice.generate_challenge`.
If this and :setting:`OTP_EMAIL_BODY_TEMPLATE_PATH` are not set, we'll render the template 'otp/email/token.txt', which you'll most likely want to override.
.. setting:: OTP_EMAIL_BODY_HTML_TEMPLATE
OTP_EMAIL_BODY_HTML_TEMPLATE
Default: None
A raw template string to use for the email html alternative body. The render context will
include the generated token in the token key. Additional template context
may be passed to
:meth:`~django_otp.plugins.otp_email.models.EmailDevice.generate_challenge`.
If this and :setting:`OTP_EMAIL_BODY_HTML_TEMPLATE_PATH` are not set, we won't attach any html alternative to the email.
.. setting:: OTP_EMAIL_BODY_TEMPLATE_PATH
OTP_EMAIL_BODY_TEMPLATE_PATH
Default: otp/email/token.txt
A path string to a template file to use for the email body. The render context
will include the generated token in the token key. Additional template
context may be passed to
:meth:`~django_otp.plugins.otp_email.models.EmailDevice.generate_challenge`.
If this and :setting:`OTP_EMAIL_BODY_TEMPLATE` are not set, we'll render the template 'otp/email/token.txt', which you'll most likely want to override.
.. setting:: OTP_EMAIL_BODY_HTML_TEMPLATE_PATH
OTP_EMAIL_BODY_HTML_TEMPLATE_PATH
Default: None
A path string to a template file to use for the email html alternative body. The render context
will include the generated token in the token key. Additional template
context may be passed to
:meth:`~django_otp.plugins.otp_email.models.EmailDevice.generate_challenge`.
If this and :setting:`OTP_EMAIL_BODY_HTML_TEMPLATE` are not set, we won't attach any html alternative to the email.
.. setting:: OTP_EMAIL_TOKEN_VALIDITY
OTP_EMAIL_TOKEN_VALIDITY
Default: 300
The maximum number of seconds a token is valid.
.. setting:: OTP_EMAIL_COOLDOWN_DURATION
OTP_EMAIL_COOLDOWN_DURATION
Default: 60
This controls the cooldown period after a successful token generation. The token can be regenerated after the designated time period has fully elapsed. Set to 0 to disable cooldown completely.
.. setting:: OTP_EMAIL_THROTTLE_FACTOR
OTP_EMAIL_THROTTLE_FACTOR
Default: 1
This controls the rate of throttling. The sequence of 1, 2, 4, 8… seconds is multiplied by this factor to define the delay imposed after 1, 2, 3, 4… successive failures. Set to 0 to disable throttling completely.
The framework author also maintains a couple of other plugins for less common devices. Third-party plugins are not listed here.
- django-otp-yubikey supports YubiKey USB devices.
- django-otp-twilio supports delivering tokens via Twilio's SMS service.
.. setting:: OTP_LOGIN_URL
OTP_LOGIN_URL
Default: alias for :setting:`LOGIN_URL`
The URL where requests are redirected for two-factor authentication, especially when using the :func:`~django_otp.decorators.otp_required` decorator.
.. setting:: OTP_ADMIN_HIDE_SENSITIVE_DATA
OTP_ADMIN_HIDE_SENSITIVE_DATA
Default: False
This controls showing some sensitive data on the Django admin site (e.g., keys and corresponding QR codes, static tokens). Note, it is respected by built-in plugins, but external ones may or may not support it.
.. glossary::
authenticated
A user whose credentials have been accepted by Django's authentication
API is considered authenticated.
device
A mechanism by which a user can acquire an OTP. This might correspond to
a physical device dedicated to such a purpose, a virtual device such as
a smart phone app, or even a set of stored single-use tokens.
OTP
A one-time password. This is a generated value that a user can present
as evidence of their identity. OTPs are only valid for a single use or,
in some cases, for a strictly limited period of time.
prover
An entity that is using an OTP to prove its identity. For example, a
user who is providing an OTP token.
token
An encoded OTP. Some OTPs consist of structured data, in which case
they will be encoded into a printable string for transport.
two-factor authentication
An authentication policy that requires a user to present two proofs of
identity. The first is typically a password and the second is
frequently tied to some physical device in the user's possession.
verified
A user whose credentials have been accepted by Django's authentication
API and also by a registered OTP device is considered verified.
verifier
An entity that verifies tokens generated by a prover. For example, a web
service that accepts OTPs as proof of identity.
Footnotes
| [1] | If you'd like the second factor to persist across sessions, see django-agent-trust and django-otp-agents. The former deals with assigning trust to user agents (i.e. browsers) across sessions and the latter includes tools to use OTPs to establish that trust. |