# Authentication

This document discusses using various kinds of authentication with Requests.

Many web services require authentication, and there are many different types. Below, we outline various forms of authentication available in Requests, from the simple to the complex.

## Basic Authentication

Many web services that require authentication accept HTTP Basic Auth. This is the simplest kind, and Requests supports it straight out of the box.

Making requests with HTTP Basic Auth is very simple:

    >>> from requests.auth import HTTPBasicAuth
    >>> basic = HTTPBasicAuth('user', 'pass')
    >>> requests.get('https://httpbin.org/basic-auth/user/pass', auth=basic)
    <Response [200]>

In fact, HTTP Basic Auth is so common that Requests provides a handy shorthand for using it:

    >>> requests.get('https://httpbin.org/basic-auth/user/pass', auth=('user', 'pass'))
    <Response [200]>

Providing the credentials in a tuple like this is exactly the same as the `HTTPBasicAuth` example above.

### netrc Authentication

If no authentication method is given with the `auth` argument, Requests will attempt to get the authentication credentials for the URL’s hostname from the user’s netrc file. The netrc file overrides raw HTTP authentication headers set with headers=.

If credentials for the hostname are found, the request is sent with HTTP Basic Auth.

Requests will search for the netrc file at ~/.netrc, ~/_netrc, or at the path specified by the NETRC environment variable. ~ denotes the user’s home directory, which is $HOME on Unix based systems and %USERPROFILE% on Windows.

Usage of netrc file can be disabled by setting trust_env to False in the Requests session:

    >>> s = requests.Session()
    >>> s.trust_env = False
    >>> s.get('https://httpbin.org/basic-auth/user/pass')

## Digest Authentication

Another very popular form of HTTP Authentication is Digest Authentication, and Requests supports this out of the box as well:

    >>> from requests.auth import HTTPDigestAuth
    >>> url = 'https://httpbin.org/digest-auth/auth/user/pass'
    >>> requests.get(url, auth=HTTPDigestAuth('user', 'pass'))
    <Response [200]>

## OAuth 1 Authentication

A common form of authentication for several web APIs is OAuth. The `requests-oauthlib` library allows Requests users to easily make OAuth 1 authenticated requests:

    >>> import requests
    >>> from requests_oauthlib import OAuth1

    >>> url = 'https://api.twitter.com/1.1/account/verify_credentials.json'
    >>> auth = OAuth1('YOUR_APP_KEY', 'YOUR_APP_SECRET',
    ...               'USER_OAUTH_TOKEN', 'USER_OAUTH_TOKEN_SECRET')

    >>> requests.get(url, auth=auth)
    <Response [200]>

For more information on how to OAuth flow works, please see the official OAuth website. For examples and documentation on requests-oauthlib, please see the requests_oauthlib repository on GitHub

## OAuth 2 and OpenID Connect Authentication

The `requests-oauthlib` library also handles OAuth 2, the authentication mechanism underpinning OpenID Connect. See the requests-oauthlib OAuth2 documentation for details of the various OAuth 2 credential management flows:

- Web Application Flow

- Mobile Application Flow

- Legacy Application Flow

- Backend Application Flow

## Other Authentication

Requests is designed to allow other forms of authentication to be easily and quickly plugged in. Members of the open-source community frequently write authentication handlers for more complicated or less commonly-used forms of authentication. Some of the best have been brought together under the Requests organization, including:

- Kerberos

- NTLM

If you want to use any of these forms of authentication, go straight to their GitHub page and follow the instructions.

## New Forms of Authentication

If you can’t find a good implementation of the form of authentication you want, you can implement it yourself. Requests makes it easy to add your own forms of authentication.

To do so, subclass `AuthBase` and implement the `__call__()` method:

    >>> import requests
    >>> class MyAuth(requests.auth.AuthBase):
    ...     def __call__(self, r):
    ...         # Implement my authentication
    ...         return r
    ...
    >>> url = 'https://httpbin.org/get'
    >>> requests.get(url, auth=MyAuth())
    <Response [200]>

When an authentication handler is attached to a request, it is called during request setup. The `__call__` method must therefore do whatever is required to make the authentication work. Some forms of authentication will additionally add hooks to provide further functionality.

Further examples can be found under the Requests organization and in the `auth.py` file.