devise-jwt
is a devise extension which uses JWT tokens for user authentication. It follows secure by default principle.
This gem is just a replacement for cookies when these can't be used. As
cookies, a token expired with devise-jwt
will mandatorily have an expiration
time. If you need that your users never sign out, you will be better off with a
solution using refresh tokens, like some implementation of OAuth2.
You can read about which security concerns this library takes into account and about JWT generic secure usage in the following series of posts:
- Stand Up for JWT Revocation
- JWT Revocation Strategies
- JWT Secure Usage
- A secure JWT authentication implementation for Rack and Rails
devise-jwt
is just a thin layer on top of warden-jwt_auth
that configures it to be used out of the box with devise and Rails.
Since version v0.7.0 Blacklist
revocation strategy has been renamed to Denylist
while Whitelist
has been renamed to Allowlist
.
For Denylist
, you only need to update the include
line you're using in your revocation strategy model:
# include Devise::JWT::RevocationStrategies::Blacklist # before
include Devise::JWT::RevocationStrategies::Denylist
For Allowlist
, you need to update the include
line you're using in your user model:
# include Devise::JWT::RevocationStrategies::Whitelist # before
include Devise::JWT::RevocationStrategies::Allowlist
You also have to rename your WhitelistedJwt
model to AllowlistedJwt
, rename model/whitelisted_jwt.rb
to model/allowlisted_jwt.rb
and change the underlying database table to allowlisted_jwts
(or configure the model to keep using the old name).
Add this line to your application's Gemfile:
gem 'devise-jwt'
And then execute:
$ bundle
Or install it yourself as:
$ gem install devise-jwt
First you need to configure devise to work in an API application. You can follow the instructions in this project wiki page Configuring devise for APIs (you are more than welcome to improve them).
First of all, you have to configure the secret key that will be used to sign generated tokens. You can do it in the devise initializer:
Devise.setup do |config|
# ...
config.jwt do |jwt|
jwt.secret = ENV['DEVISE_JWT_SECRET_KEY']
end
end
Important: You are encouraged to use a secret different than your application secret_key_base
. It is quite possible that some other component of your system is already using it. If several components share the same secret key, chances that a vulnerability in one of them has a wider impact increase. In rails, generating new secrets is as easy as bundle exec rake secret
. Also, never share your secrets pushing it to a remote repository, you are better off using an environment variable like in the example.
Currently, HS256 algorithm is the one in use.
You have to tell which user models you want to be able to authenticate with JWT tokens. For them, the authentication process will be like this:
- A user authenticates through devise create session request (for example, using the standard
:database_authenticatable
module). - If the authentication succeeds, a JWT token is dispatched to the client in the
Authorization
response header, with formatBearer #{token}
(tokens are also dispatched on a successful sign up). - The client can use this token to authenticate following requests for the same user, providing it in the
Authorization
request header, also with formatBearer #{token}
- When the client visits devise destroy session request, the token is revoked.
See request_formats configuration option if you are using paths with a format segment (like .json
) in order to use it properly.
As you see, unlike other JWT authentication libraries, it is expected that tokens will be revoked by the server. I wrote about why I think JWT revocation is needed and useful.
An example configuration:
class User < ApplicationRecord
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: Denylist
end
If you need to add something to the JWT payload, you can do it defining a jwt_payload
method in the user model. It must return a Hash
. For instance:
def jwt_payload
{ 'foo' => 'bar' }
end
You can add a hook method on_jwt_dispatch
on the user model. It is executed when a token dispatched for that user instance, and it takes token
and payload
as parameters.
def on_jwt_dispatch(token, payload)
do_something(token, payload)
end
Note: if you are making cross-domain requests, make sure that you add Authorization
header to the list of allowed request headers and exposed response headers. You can use something like rack-cors for that, for example:
config.middleware.insert_before 0, Rack::Cors do
allow do
origins 'http://your.frontend.domain.com'
resource '/api/*',
headers: %w(Authorization),
methods: :any,
expose: %w(Authorization),
max_age: 600
end
end
If you are working with a Rails application that has session storage enabled and a default devise setup, chances are that same origin requests will be authenticated from the session regardless of a token being present in the headers or not.
This is so because of the following default devise workflow:
- When a user signs in with
:database_authenticatable
strategy, the user is stored in the session unless one of the following conditions is met:- Session is disabled.
- Devise
config.skip_session_storage
includes:params_auth
. - Rails Request forgery protection handles an unverified request (but this is usually deactivated for API requests).
- Warden (the engine below devise), authenticates any request that has the user
in the session without even reaching to any strategy (
:jwt_authenticatable
in our case).
So, if you want to avoid this caveat you have three options:
- Disable the session. If you are developing an API, probably you don't need
it. In order to disable it, change
config/initializers/session_store.rb
to:Notice that if you created the application with theRails.application.config.session_store :disabled
--api
flag you already have the session disabled. - If you still need the session for any other purpose, disable
:database_authenticatable
user storage. Inconfig/initializers/devise.rb
:config.skip_session_storage = [:http_auth, :params_auth]
- If you are using Devise for another model (e.g.
AdminUser
) and doesn't want to disable session storage for devise entirely, you can disable it on a per-model basis:class User < ApplicationRecord devise :database_authenticatable #, your other enabled modules... self.skip_session_storage = [:http_auth, :params_auth] end
devise-jwt
comes with three revocation strategies out of the box. Some of them are implementations of what is discussed in the blog post JWT Revocation Strategies, where I also talk about their pros and cons.
Here, the model class acts itself as the revocation strategy. It needs a new string column with name jti
to be added to the user. jti
stands for JWT ID, and it is a standard claim meant to uniquely identify a token.
It works like the following:
- When a token is dispatched for a user, the
jti
claim is taken from thejti
column in the model (which has been initialized when the record has been created). - At every authenticated action, the incoming token
jti
claim is matched against thejti
column for that user. The authentication only succeeds if they are the same. - When the user requests to sign out its
jti
column changes, so that provided token won't be valid anymore.
In order to use it, you need to add the jti
column to the user model. So, you have to set something like the following in a migration:
def change
add_column :users, :jti, :string, null: false
add_index :users, :jti, unique: true
# If you already have user records, you will need to initialize its `jti` column before setting it to not nullable. Your migration will look this way:
# add_column :users, :jti, :string
# User.all.each { |user| user.update_column(:jti, SecureRandom.uuid) }
# change_column_null :users, :jti, false
# add_index :users, :jti, unique: true
end
Important: You are encouraged to set a unique index in the jti
column. This way we can be sure at the database level that there aren't two valid tokens with same jti
at the same time.
Then, you have to add the strategy to the model class and configure it accordingly:
class User < ApplicationRecord
include Devise::JWT::RevocationStrategies::JTIMatcher
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: self
end
Be aware that this strategy makes uses of jwt_payload
method in the user model, so if you need to use it don't forget to call super
:
def jwt_payload
super.merge('foo' => 'bar')
end
In this strategy, a database table is used as a list of revoked JWT tokens. The jti
claim, which uniquely identifies a token, is persisted. The exp
claim is also stored to allow the clean-up of staled tokens.
In order to use it, you need to create the denylist table in a migration:
def change
create_table :jwt_denylist do |t|
t.string :jti, null: false
t.datetime :exp, null: false
end
add_index :jwt_denylist, :jti
end
For performance reasons, it is better if the jti
column is an index.
Note: if you used the denylist strategy before vesion 0.4.0 you may not have the field exp. If not, run the following migration:
class AddExpirationTimeToJWTDenylist < ActiveRecord::Migration
def change
add_column :jwt_denylist, :exp, :datetime, null: false
end
end
Then, you need to create the corresponding model and include the strategy:
class JwtDenylist < ApplicationRecord
include Devise::JWT::RevocationStrategies::Denylist
self.table_name = 'jwt_denylist'
end
Last, configure the user model to use it:
class User < ApplicationRecord
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: JwtDenylist
end
Here, the model itself acts also as a revocation strategy, but it needs to have
a one-to-many association with another table which stores the tokens (in fact
their jti
claim, which uniquely identifies them) valids for each user record.
The workflow is as the following:
- Once a token is dispatched for a user, its
jti
claim is stored in the associated table. - At every authentication, the incoming token
jti
is matched against all thejti
associated to that user. The authentication only succeeds if one of them matches. - On a sign out, the token
jti
is deleted from the associated table.
In fact, besides the jti
claim, the aud
claim is also stored and matched at
every authentication. This, together with the aud_header
configuration parameter, can be used to differentiate between clients or
devices for the same user.
The exp
claim is also stored to allow the clean-up of staled tokens.
In order to use it, you have to create yourself the associated table and model.
The association table must be called allowlisted_jwts
:
def change
create_table :allowlisted_jwts do |t|
t.string :jti, null: false
t.string :aud
# If you want to leverage the `aud` claim, add to it a `NOT NULL` constraint:
# t.string :aud, null: false
t.datetime :exp, null: false
t.references :your_user_table, foreign_key: { on_delete: :cascade }, null: false
end
add_index :allowlisted_jwts, :jti, unique: true
end
Important: You are encouraged to set a unique index in the jti column. This way we can be sure at the database level that there aren't two valid tokens with same jti at the same time. Definining foreign_key: { on_delete: :cascade }, null: false
on t.references :your_user_table
helps to keep referential integrity of your database.
And then, the model:
class AllowlistedJwt < ApplicationRecord
end
Finally, include the strategy in the model and configure it:
class User < ApplicationRecord
include Devise::JWT::RevocationStrategies::Allowlist
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: self
end
Be aware that this strategy makes uses of on_jwt_dispatch
method in the user model, so if you need to use it don't forget to call super
:
def on_jwt_dispatch(token, payload)
super
do_something(token, payload)
end
A null object pattern strategy, which does not revoke tokens, is provided out of the box just in case you are absolutely sure you don't need token revocation. It is recommended not to use it.
class User < ApplicationRecord
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: Devise::JWT::RevocationStrategies::Null
end
You can also implement your own strategies. They just need to implement two methods: jwt_revoked?
and revoke_jwt
, both of them accepting as parameters the JWT payload and the user record, in this order.
For instance:
module MyCustomStrategy
def self.jwt_revoked?(payload, user)
# Does something to check whether the JWT token is revoked for given user
end
def self.revoke_jwt(payload, user)
# Does something to revoke the JWT token for given user
end
end
class User < ApplicationRecord
devise :database_authenticatable,
:jwt_authenticatable, jwt_revocation_strategy: MyCustomStrategy
end
Models configured with :jwt_authenticatable
usually won't be retrieved from
the session. For this reason, sign_in
devise testing helper methods won't
work as expected.
What you need to do in order to authenticate test environment requests is the
same that you will do in production: to provide a valid token in the
Authorization
header (in the form of Bearer #{token}
) at every request.
There are two ways you can get a valid token:
- Inspecting the
Authorization
response header after a valid sign in request. - Manually creating it.
The first option tests the real workflow of your application, but it can slow things if you perform it at every test.
For the second option, a test helper is provided in order to add the
Authorization
name/value pair to given request headers. You can use it as in
the following example:
# First, require the helper module
require 'devise/jwt/test_helpers'
# ...
it 'tests something' do
user = fetch_my_user()
headers = { 'Accept' => 'application/json', 'Content-Type' => 'application/json' }
# This will add a valid token for `user` in the `Authorization` header
auth_headers = Devise::JWT::TestHelpers.auth_headers(headers, user)
get '/my/end_point', headers: auth_headers
expect_something()
end
Usually you will wrap this in your own test helper.
This library can be configured calling jwt
on devise config object:
Devise.setup do |config|
config.jwt do |jwt|
# ...
end
end
Secret key used to sign generated JWT tokens. You must set it.
Number of seconds while a JWT is valid after its generation. After that, it won't be valid anymore, even if it hasn't been revoked.
Defaults to 3600 (1 hour).
Besides the create session one, additional requests where JWT tokens should be dispatched.
It must be a bidimensional array, each item being an array of two elements: the request method and a regular expression that must match the request path.
For example:
jwt.dispatch_requests = [
['POST', %r{^/dispatch_path_1$}],
['GET', %r{^/dispatch_path_2$}],
]
Important: You are encouraged to delimit your regular expression with ^
and $
to avoid unintentional matches.
Besides the destroy session one, additional requests where JWT tokens should be revoked.
It must be a bidimensional array, each item being an array of two elements: the request method and a regular expression that must match the request path.
For example:
jwt.revocation_requests = [
['DELETE', %r{^/revocation_path_1$}],
['GET', %r{^/revocation_path_2$}],
]
Important: You are encouraged to delimit your regular expression with ^
and $
to avoid unintentional matches.
Request formats that must be processed (in order to dispatch or revoke tokens).
It must be a hash of devise scopes as keys and an array of request formats as values. When a scope is not present or if it has a nil item, requests without format will be taken into account.
For example, with following configuration, user
scope would dispatch and
revoke tokens in json
requests (as in /users/sign_in.json
), while
admin_user
would do it in xml
and with no format (as in
/admin_user/sign_in.xml
and /admin_user/sign_in
).
jwt.request_formats = {
user: [:json],
admin_user: [nil, :xml]
}
By default, only requests without format are processed.
Request header which content will be stored to the aud
claim in the payload.
It is used to validate whether an incoming token was originally issued to the
same client, checking if aud
and the aud_header
header value match. If you
don't want to differentiate between clients, you don't need to provide that
header.
Important: Be aware that this workflow is not bullet proof. In some scenarios a user can handcraft the request headers, therefore being able to impersonate any client. In such cases you could need something more robust, like an OAuth workflow with client id and client secret.
Defaults to JWT_AUD
.
There are docker and docker-compose files configured to create a development environment for this gem. So, if you use Docker you only need to run:
docker-compose up -d
An then, for example:
docker-compose exec app rspec
Bug reports and pull requests are welcome on GitHub at https://github.com/waiting-for-dev/devise-jwt. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
devise-jwt
follows the principles of semantic versioning.
The gem is available as open source under the terms of the MIT License.