diff --git a/README.md b/README.md
index ae312c9..719cd7b 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,7 @@ That approach works perfectly fine, but is a bit heavy-handed and cumbersome. Th
    `gem "redmine_github_hook"`
 2. `bundle`
 3. Restart your Redmine
+4. Enable **Enable WS for repository management** in **Administration** > **Settings** > **Repositories** and generate an API key
 
 ### 2. Add the repository to Redmine
 
@@ -32,9 +33,9 @@ Adding a Git repository to a project (note, this should work whether you want to
 1. Go to the repository Settings interface on GitHub.
 2. Under "Webhooks & Services" add a new "WebHook". The "Payload URL" needs to be of the format: `[redmine_url]/github_hook` (for example `http://redmine.example.com/github_hook`).
    * By default, GitHub Hook assumes your GitHub repository name is the same as the *project identifier* in your Redmine installation.
-     * If this is not the case, you can specify the actual Redmine project identifier in the Post-Receive URL by using the format `[redmine_url]/github_hook?project_id=[identifier]` (for example `http://redmine.example.com/github_hook?project_id=my_project`).
+     * If this is not the case, you can specify the actual Redmine project identifier in the Post-Receive URL by using the format `[redmine_url]/github_hook?key=[api_key]&project_id=[identifier]` (for example `http://redmine.example.com/github_hook?key=my_api_key&project_id=my_project`).
      * GitHub Hook will then update **all repositories** in the specified project. *Be aware, that this process may take a while if you have many repositories in your project.*
-     * If you want GitHub Hook to **only update the current repository** you can specify it with an additional parameter in the Post-Receive URL by using the format `[redmine_url]/github_hook?project_id=[identifier]&repository_id=[repository]` (for example `http://redmine.example.com/github_hook?project_id=my_project&repository_id=my_repo`).
+     * If you want GitHub Hook to **only update the current repository** you can specify it with an additional parameter in the Post-Receive URL by using the format `[redmine_url]/github_hook?key=[api_key]&project_id=[identifier]&repository_id=[repository]` (for example `http://redmine.example.com/github_hook?key=my_api_key&project_id=my_project&repository_id=my_repo`).
    * In most cases, just having the "push" event trigger the webhook should suffice, but you are free to customize the events as you desire.
    * *Note: Make sure you're adding a Webhook - which is what Redmine Github Hook expects. GitHub has some builtin Redmine integration; that's not what you're looking for.*
 
diff --git a/app/controllers/github_hook_controller.rb b/app/controllers/github_hook_controller.rb
index 620bf35..8e4033c 100644
--- a/app/controllers/github_hook_controller.rb
+++ b/app/controllers/github_hook_controller.rb
@@ -1,6 +1,7 @@
 require "json"
 
 class GithubHookController < ApplicationController
+  before_filter :check_enabled
   skip_before_filter :verify_authenticity_token, :check_if_login_required
 
   def index
@@ -41,4 +42,12 @@ def update_repository(logger)
     updater.logger = logger
     updater.call
   end
+
+  def check_enabled
+    User.current = nil
+    unless Setting.sys_api_enabled? && (Setting.sys_api_key.empty? || params[:key].to_s == Setting.sys_api_key)
+      render :text => 'Access denied. Repository management WS is disabled or key is invalid.', :status => 403
+      return false
+    end
+  end
 end
diff --git a/test/functional/github_hook_controller_test.rb b/test/functional/github_hook_controller_test.rb
index 7d5a5e0..ed96925 100644
--- a/test/functional/github_hook_controller_test.rb
+++ b/test/functional/github_hook_controller_test.rb
@@ -65,6 +65,8 @@ def project
   end
 
   def setup
+    Setting.sys_api_enabled = '1'
+    Setting.sys_api_key = 'my_secret_key'
     Project.stubs(:find_by_identifier).with("github").returns(project)
 
     # Make sure we don't run actual commands in test
@@ -72,8 +74,12 @@ def setup
     Repository.expects(:fetch_changesets).never
   end
 
-  def do_post
-    post :index, :payload => json
+  def teardown
+    Setting.clear_cache
+  end
+
+  def do_post(key: 'my_secret_key')
+    post :index, :payload => json, :key => key
   end
 
   def test_should_render_response_from_github_hook_when_done
@@ -83,6 +89,27 @@ def test_should_render_response_from_github_hook_when_done
     assert_match "GithubHook: Redmine repository updated", @response.body
   end
 
+  def test_should_render_response_from_github_hook_when_done_with_empty_sys_api_key
+    GithubHook::Updater.any_instance.expects(:update_repository).returns(true)
+    with_settings :sys_api_key => '' do
+      do_post :key => 'wrong_key'
+    end
+    assert_response :success
+    assert_match "GithubHook: Redmine repository updated", @response.body
+  end
+
+  def test_disabled_ws_should_respond_with_403
+    with_settings :sys_api_enabled => '0' do
+      do_post
+      assert_response 403
+    end
+  end
+
+  def test_wrong_key_should_respond_with_403
+    do_post :key => 'wrong_key'
+    assert_response 403
+  end
+
   def test_should_render_error_message
     GithubHook::Updater
       .any_instance
@@ -115,7 +142,12 @@ def test_exec_should_log_output_from_git_as_error_when_things_go_sour
   end
 
   def test_should_respond_to_get
-    get :index
+    get :index, :key => 'my_secret_key'
     assert_response :success
   end
+
+  def test_wrong_key_should_respond_to_get_with_403
+    get :index, :key => 'wrong_key'
+    assert_response 403
+  end
 end