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src/docs/src/api/server/authn.rst

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.. Licensed under the Apache License, Version 2.0 (the "License"); you may not .. use this file except in compliance with the License. You may obtain a copy of .. the License at .. .. http://www.apache.org/licenses/LICENSE-2.0 .. .. Unless required by applicable law or agreed to in writing, software .. distributed under the License is distributed on an "AS IS" BASIS, WITHOUT .. WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the .. License for the specific language governing permissions and limitations under .. the License.

.. _api/auth:

============== Authentication

Interfaces for obtaining session and authorization data.

.. note:: We also strongly recommend you :ref:set up SSL <config/ssl> to improve all authentication methods' security.

.. _api/auth/basic:

Basic Authentication

.. versionchanged:: 3.4 In order to aid transition to stronger password hashing without causing a performance penalty, CouchDB will send a Set-Cookie header when a request authenticates successfully with Basic authentication. All browsers and many http libraries will automatically send this cookie on subsequent requests. The cost of verifying the cookie is significantly less than PBKDF2 with a high iteration count, for example.

Basic authentication_ (:rfc:2617) is a quick and simple way to authenticate with CouchDB. The main drawback is the need to send user credentials with each request which may be insecure and could hurt operation performance (since CouchDB must compute the password hash with every request):

Request:

.. code-block:: http

GET / HTTP/1.1
Accept: application/json
Authorization: Basic cm9vdDpyZWxheA==
Host: localhost:5984

Response:

.. code-block:: http

HTTP/1.1 200 OK
Cache-Control: must-revalidate
Content-Length: 177
Content-Type: application/json
Date: Mon, 03 Dec 2012 00:44:47 GMT
Server: CouchDB (Erlang/OTP)

{
    "couchdb":"Welcome",
    "uuid":"0a959b9b8227188afc2ac26ccdf345a6",
    "version":"1.3.0",
    "vendor": {
        "version":"1.3.0",
        "name":"The Apache Software Foundation"
    }
}

.. _Basic authentication: http://en.wikipedia.org/wiki/Basic_access_authentication

.. _api/auth/cookie:

Cookie Authentication

For cookie authentication (:rfc:2109) CouchDB generates a token that the client can use for the next few requests to CouchDB. Tokens are valid until a timeout. When CouchDB sees a valid token in a subsequent request, it will authenticate the user by this token without requesting the password again. By default, cookies are valid for 10 minutes, but it's adjustable via :config:option:timeout <chttpd_auth/timeout>. Also it's possible to make cookies :config:option:persistent <chttpd_auth/allow_persistent_cookies>.

To obtain the first token and thus authenticate a user for the first time, the username and password must be sent to the :ref:_session API <api/auth/session>.

.. _api/auth/session:

/_session

.. http:post:: /_session :synopsis: Authenticates user by Cookie-based user login

Initiates new session for specified user credentials by providing `Cookie`
value.

:<header Content-Type: - :mimetype:`application/x-www-form-urlencoded`
                       - :mimetype:`application/json`
:query string next: Enforces redirect after successful login to the
  specified location. This location is relative from server root.
  *Optional*.
:form name: User name
:form password: Password
:>header Set-Cookie: Authorization token
:>json boolean ok: Operation status
:>json string name: Username
:>json array roles: List of user roles
:code 200: Successfully authenticated
:code 302: Redirect after successful authentication
:code 401: Username or password wasn't recognized
:code 403: Insufficient permissions / :ref:`Too many requests with invalid credentials<error/403>`

**Request**:

.. code-block:: http

    POST /_session HTTP/1.1
    Accept: application/json
    Content-Length: 24
    Content-Type: application/x-www-form-urlencoded
    Host: localhost:5984

    name=root&password=relax

It's also possible to send data as JSON:

.. code-block:: http

    POST /_session HTTP/1.1
    Accept: application/json
    Content-Length: 37
    Content-Type: application/json
    Host: localhost:5984

    {
        "name": "root",
        "password": "relax"
    }

**Response**:

.. code-block:: http

    HTTP/1.1 200 OK
    Cache-Control: must-revalidate
    Content-Length: 43
    Content-Type: application/json
    Date: Mon, 03 Dec 2012 01:23:14 GMT
    Server: CouchDB (Erlang/OTP)
    Set-Cookie: AuthSession=cm9vdDo1MEJCRkYwMjq0LO0ylOIwShrgt8y-UkhI-c6BGw; Version=1; Path=/; HttpOnly

    {"ok":true,"name":"root","roles":["_admin"]}

If ``next`` query parameter was provided the response will trigger
redirection to the specified location in case of successful authentication:

**Request**:

.. code-block:: http

    POST /_session?next=/blog/_design/sofa/_rewrite/recent-posts HTTP/1.1
    Accept: application/json
    Content-Type: application/x-www-form-urlencoded
    Host: localhost:5984

    name=root&password=relax

**Response**:

.. code-block:: http

    HTTP/1.1 302 Moved Temporarily
    Cache-Control: must-revalidate
    Content-Length: 43
    Content-Type: application/json
    Date: Mon, 03 Dec 2012 01:32:46 GMT
    Location: http://localhost:5984/blog/_design/sofa/_rewrite/recent-posts
    Server: CouchDB (Erlang/OTP)
    Set-Cookie: AuthSession=cm9vdDo1MEJDMDEzRTp7Vu5GKCkTxTVxwXbpXsBARQWnhQ; Version=1; Path=/; HttpOnly

    {"ok":true,"name":null,"roles":["_admin"]}

.. http:get:: /_session :synopsis: Returns Cookie-based login user information

Returns information about the authenticated user, including a
:ref:`userctx_object`, the authentication method and database that were
used, and a list of configured authentication handlers on the server.

:query boolean basic: Accept `Basic Auth` by requesting this resource.
  *Optional*.
:>json boolean ok: Operation status
:>json object userCtx: User context for the current user
:>json object info: Server authentication configuration
:code 200: Successfully authenticated.
:code 401: Username or password wasn't recognized.
:code 403: Insufficient permissions / :ref:`Too many requests with invalid credentials<error/403>`

**Request**:

.. code-block:: http

    GET /_session HTTP/1.1
    Host: localhost:5984
    Accept: application/json
    Cookie: AuthSession=cm9vdDo1MEJDMDQxRDpqb-Ta9QfP9hpdPjHLxNTKg_Hf9w

**Response**:

.. code-block:: http

    HTTP/1.1 200 OK
    Cache-Control: must-revalidate
    Content-Length: 175
    Content-Type: application/json
    Date: Fri, 09 Aug 2013 20:27:45 GMT
    Server: CouchDB (Erlang/OTP)
    Set-Cookie: AuthSession=cm9vdDo1MjA1NTBDMTqmX2qKt1KDR--GUC80DQ6-Ew_XIw; Version=1; Path=/; HttpOnly

    {
        "info": {
            "authenticated": "cookie",
            "authentication_db": "_users",
            "authentication_handlers": [
                "cookie",
                "default"
            ]
        },
        "ok": true,
        "userCtx": {
            "name": "root",
            "roles": [
                "_admin"
            ]
        }
    }

.. http:delete:: /_session :synopsis: Logout Cookie-based user

Closes user's session by instructing the browser to clear the cookie. This
does not invalidate the session from the server's perspective, as there is
no way to do this because CouchDB cookies are stateless. This means calling
this endpoint is purely optional from a client perspective, and it does not
protect against theft of a session cookie.

:code 200: Successfully close session.

**Request**:

.. code-block:: http

    DELETE /_session HTTP/1.1
    Accept: application/json
    Cookie: AuthSession=cm9vdDo1MjA1NEVGMDo1QXNQkqC_0Qmgrk8Fw61_AzDeXw
    Host: localhost:5984

**Response**:

.. code-block:: http

    HTTP/1.1 200 OK
    Cache-Control: must-revalidate
    Content-Length: 12
    Content-Type: application/json
    Date: Fri, 09 Aug 2013 20:30:12 GMT
    Server: CouchDB (Erlang/OTP)
    Set-Cookie: AuthSession=; Version=1; Path=/; HttpOnly

    {
        "ok": true
    }

.. _api/auth/proxy:

Proxy Authentication

.. note:: To use this authentication method make sure that the {chttpd_auth, proxy_authentication_handler} value is added to the list of the active :config:option:chttpd/authentication_handlers:

.. code-block:: ini

    [chttpd]
    authentication_handlers = {chttpd_auth, cookie_authentication_handler}, {chttpd_auth, proxy_authentication_handler}, {chttpd_auth, default_authentication_handler}

Proxy authentication is very useful in case your application already uses some external authentication service and you don't want to duplicate users and their roles in CouchDB.

This authentication method allows creation of a :ref:userctx_object for remotely authenticated user. By default, the client just needs to pass specific headers to CouchDB with related requests:

  • :config:option:X-Auth-CouchDB-UserName <chttpd_auth/x_auth_username>: username
  • :config:option:X-Auth-CouchDB-Roles <chttpd_auth/x_auth_roles>: comma-separated (,) list of user roles
  • :config:option:X-Auth-CouchDB-Token <chttpd_auth/x_auth_token>: authentication token. When :config:option:proxy_use_secret <chttpd_auth/proxy_use_secret> is set (which is strongly recommended!), this header provides an HMAC of the username to authenticate and the secret token to prevent requests from untrusted sources. (Use one of the configured hash algorithms in :config:option:chttpd_auth/hash_algorithms <chttpd_auth/hash_algorithms> and sign the username with the secret)

Creating the token (example with openssl):

.. code-block:: sh

echo -n "foo" | openssl dgst -sha256 -hmac "the_secret"
# (stdin)= 3f0786e96b20b0102b77f1a49c041be6977cfb3bf78c41a12adc121cd9b4e68a

Request:

.. code-block:: http

GET /_session HTTP/1.1
Host: localhost:5984
Accept: application/json
Content-Type: application/json; charset=utf-8
X-Auth-CouchDB-Roles: users,blogger
X-Auth-CouchDB-UserName: foo
X-Auth-CouchDB-Token: 3f0786e96b20b0102b77f1a49c041be6977cfb3bf78c41a12adc121cd9b4e68a

Response:

.. code-block:: http

HTTP/1.1 200 OK
Cache-Control: must-revalidate
Content-Length: 190
Content-Type: application/json
Date: Fri, 14 Jun 2013 10:16:03 GMT
Server: CouchDB (Erlang/OTP)

{
    "info": {
        "authenticated": "proxy",
        "authentication_db": "_users",
        "authentication_handlers": [
            "cookie",
            "proxy",
            "default"
        ]
    },
    "ok": true,
    "userCtx": {
        "name": "foo",
        "roles": [
            "users",
            "blogger"
        ]
    }
}

Note that you don't need to request a :ref:session <api/auth/session> to be authenticated by this method if all required HTTP headers are provided.

.. _api/auth/jwt:

JWT Authentication

.. note:: To use this authentication method, make sure that the {chttpd_auth, jwt_authentication_handler} value is added to the list of the active :config:option:chttpd/authentication_handlers:

.. code-block:: ini

    [chttpd]
    authentication_handlers = {chttpd_auth, cookie_authentication_handler}, {chttpd_auth, jwt_authentication_handler}, {chttpd_auth, default_authentication_handler}

JWT authentication enables CouchDB to use externally-generated JWT tokens instead of defining users or roles in the _users database.

The JWT authentication handler requires that all JWT tokens are signed by a key that CouchDB has been configured to trust (there is no support for JWT's "NONE" algorithm).

Additionally, CouchDB can be configured to reject JWT tokens that are missing a configurable set of claims (e.g, a CouchDB administrator could insist on the exp claim).

Only claims listed in required checks are validated. Additional claims will be ignored.

Two sections of config exist to configure JWT authentication;

The :config:option:required_claims <jwt_auth/required_claims> config setting is a comma-separated list of additional mandatory JWT claims that must be present in any presented JWT token. A :statuscode:400 is sent if any are missing.

The alg claim is mandatory as it used to lookup the correct key for verifying the signature.

The sub claim is mandatory and is used as the CouchDB user's name if the JWT token is valid.

You can set the user roles claim name through the config setting :config:option:roles_claim_name <jwt_auth/roles_claim_name>. If you don't set an explicit value, then _couchdb.roles will be set as the default claim name. If presented, it is used as the CouchDB user's roles list as long as the JWT token is valid.

.. note::

Before CouchDB v3.3.2 it was only possible to define roles as a JSON
array of strings. Now you can also use a comma-seperated list to define
the user roles in your JWT token. The following declarations
are equal:

JSON array of strings:

.. code-block:: json

    {
        "_couchdb.roles": ["accounting-role", "view-role"]
    }

JSON comma-seperated strings:

.. code-block:: json

    {
        "_couchdb.roles": "accounting-role, view-role"
    }

.. warning::

``roles_claim_name`` is deprecated in CouchDB 3.3, and will be removed later.
Please use :config:option:`roles_claim_path <jwt_auth/roles_claim_path>`.

.. code-block:: ini

; [jwt_keys]
; Configure at least one key here if using the JWT auth handler.
; If your JWT tokens do not include a "kid" attribute, use "_default"
; as the config key, otherwise use the kid as the config key.
; Examples
; hmac:_default = aGVsbG8=
; hmac:foo = aGVsbG8=
; The config values can represent symmetric and asymmetric keys.
; For symmetric keys, the value is base64 encoded;
; hmac:_default = aGVsbG8= # base64-encoded form of "hello"
; For asymmetric keys, the value is the PEM encoding of the public
; key with newlines replaced with the escape sequence \n.
; rsa:foo = -----BEGIN PUBLIC KEY-----\nMIIBIjAN...IDAQAB\n-----END PUBLIC KEY-----\n
; ec:bar = -----BEGIN PUBLIC KEY-----\nMHYwEAYHK...AzztRs\n-----END PUBLIC KEY-----\n

The jwt_keys section lists all the keys that this CouchDB server trusts. You should ensure that all nodes of your cluster have the same list.

Since version 3.3 it's possible to use = in parameter names, but only when the parameter and value are separated :literal:\  = \ , i.e. the equal sign is surrounded by at least one space on each side. This might be useful in the [jwt_keys] section where base64 encoded keys may contain the = character.

JWT tokens that do not include a kid claim will be validated against the {alg}:_default key.

It is mandatory to specify the algorithm associated with every key for security reasons (notably presenting a HMAC-signed token using an RSA or EC public key that the server trusts: https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/).

Request:

.. code-block:: http

GET /_session HTTP/1.1
Host: localhost:5984
Accept: application/json
Content-Type: application/json; charset=utf-8
Authorization: Bearer <JWT token>

Response:

.. code-block:: http

HTTP/1.1 200 OK
Cache-Control: must-revalidate
Content-Length: 188
Content-Type: application/json
Date: Sun, 19 Apr 2020 08:29:15 GMT
Server: CouchDB (Erlang/OTP)

{
    "info": {
        "authenticated": "jwt",
        "authentication_db": "_users",
        "authentication_handlers": [
            "cookie",
            "proxy",
            "default"
        ]
    },
    "ok": true,
    "userCtx": {
        "name": "foo",
        "roles": [
            "users",
            "blogger"
        ]
    }
}

Note that you don't need to request :ref:session <api/auth/session> to be authenticated by this method if the required HTTP header is provided.

Two-Factor Authentication (2FA)

CouchDB supports built-in time-based one-time password (TOTP) authentication, so that 2FA can be enabled for any user without extra plugins or tools. Here’s how it can be set up.

Setting up 2FA in CouchDB

  1. Generate random token key

A random base32_ string is generated and used as the user’s TOTP secret. For example_, the following command produces a secure, random key:

.. _base32: https://en.wikipedia.org/wiki/Base32 .. _example: https://support.yubico.com/hc/en-us/articles/360015668699-Generating-Base32-string-examples

.. code-block:: bash

LC_ALL=C tr -dc 'A-Z2-7' </dev/urandom | head -c 32; echo

2. Create a user with TOTP

The TOTP settings are stored per user in the _users database. Use the generated key under the totp.key.field:

.. code-block:: bash

curl -X PUT http://admin:password@localhost:5984/_users/org.couchdb.user:USERNAME \
-H "Content-Type: application/json" \
-d '{
    "name": "USERNAME",
    "password": "PASSWORD",
    "roles": [],
    "type": "user",
    "totp": { "key": "YOURTOKEN" }
}'

3. Add the secret to the TOTP app

Add the secret in the authenticator app. Apps like Aegis, 2FAS, Ente, Google Authenticator etc. can be used to generate the authentication tokens based on the TOTP key.

Logging in with 2FA

Now that the user is set up with TOTP, you can log in by sending a POST request to /_session with name, password, and token from the authenticator app.

Request:

.. code-block:: http

POST /_session HTTP/1.1
Host: localhost:5984
Accept: application/json
Content-Type: application/json; charset=utf-8

{
    "name": "USERNAME",
    "password": "PASSWORD",
    "token": "123456"
}

Response:

.. code-block:: javascript

{"ok": true, "name": "USERNAME", "roles": []}

Reuse sessions

To reuse a session save the session cookie as such:

.. code-block:: bash

curl -c cookie.txt -X POST http://localhost:5984/_session \
    -H "Content-Type: application/json" \
    -d '{"name": "USERNAME", "password": "PASSWORD", "token": "123456"}'

Then reuse it in future requests:

.. code-block:: bash

# Example using the cookie.txt
curl -b cookie.txt http://localhost:5984/DB_NAME/DOC_NAME

# Example passing AuthSession directly
curl -H "Cookie: AuthSession=AUTH_SESSION_COOKIE" http://localhost:5984/DB_NAME/DOC_NAME