DeviseSamlAuthenticatable

Devise Saml Authenticatable is a Single-Sign-On authentication strategy for devise that relies on SAML. It uses ruby-saml to handle all SAML related stuff.

Installation

Add this line to your application's Gemfile:

gem 'devise_saml_authenticatable'

And then execute:

$ bundle

Or install it yourself as:

$ gem install devise_saml_authenticatable

Usage

In app/models/<YOUR_MODEL>.rb set the :saml_authenticatable strategy. In the example the model is user.rb:

  class User < ActiveRecord::Base
    ...
    devise :saml_authenticatable, :trackable
    ...
  end

In config/initializers/devise.rb

  Devise.setup do |config|
    ...
    # ==> Configuration for :saml_authenticatable
    
    # Create user if the user does not exist. (Default is false)
    config.saml_create_user = true
    
    # Set the default user key. The user will be looked up by this key. Make
    # sure that the Authentication Response includes the attribute.
    config.saml_default_user_key = :email

    # Configure with your SAML settings (see [ruby-saml][] for more information).
    config.saml_configure do |settings|
      settings.assertion_consumer_service_url     = "http://localhost:3000/users/sign_in"
      settings.assertion_consumer_service_binding = "urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
      settings.name_identifier_format             = "urn:oasis:names:tc:SAML:2.0:nameid-format:transient"
      settings.issuer                             = "http://localhost:3000"
      settings.authn_context                      = ""
      settings.idp_sso_target_url                 = "http://localhost/simplesaml/www/saml2/idp/SSOService.php"
      settings.idp_cert                           = <<-CERT.chomp
-----BEGIN CERTIFICATE-----
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111_______IDP_CERTIFICATE________111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111111111111111
111111111111111111
-----END CERTIFICATE-----
      CERT
    end
  end

In config directory create a YAML file (attribute-map.yml) that maps SAML attributes with your model's fields:

  # attribute-map.yml
  
  "urn:mace:dir:attribute-def:uid": "user_name"
  "urn:mace:dir:attribute-def:email": "email"
  "urn:mace:dir:attribute-def:name": "last_name"
  "urn:mace:dir:attribute-def:givenName": "name"

The attribute mappings are very dependent on the way the IdP encodes the attributes. In this example the attributes are given in URN style. Other IdPs might provide them as OID's or other means.

You are now ready to test it against an IdP. When the user goes to /users/saml/sign_in he will be redirected to the login page of the IdP. Upon successful login the user is redirected to devise user_root_path.

Identity Provider

If you don't have an identity provider an you would like to test the authentication against your app there are some options:

1. Use ruby-saml-idp. You can add your own logic to your IdP, or you can also set it as a dummy IdP that always sends a valid authentication response to your app.
2. Use an online service that can act as an IdP. Onelogin, Salesforce and some others provide you with this functionality
3. Install your own IdP.

There are numerous IdPs that support SAML 2.0, there are propietary (like Microsoft ADFS 2.0 or Ping federate) and there are also open source solutions like Shibboleth and simplesamlphp.

SimpleSAMLphp was my choice for development since it is a production-ready SAML solution, that is also really easy to install, configure and use.

Limitations

1. At the moment there is no support for Single Logout
2. The Authentication Requests (from your app to the IdP) are not signed and encrypted

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request