3. first, set up the keratin authn libraries for your server and client

Gemfile

@@ -4,3 +4,4 @@ gem 'puma'
 gem 'sqlite3'
 gem 'sinatra', require: 'sinatra'
 gem 'sinatra-sequel'
+gem 'keratin-authn'

Gemfile.lock

@@ -1,10 +1,31 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    activesupport (5.1.0)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+    bindata (2.4.0)
+    concurrent-ruby (1.0.5)
+    i18n (0.8.1)
+    json-jwt (1.7.1)
+      activesupport
+      bindata
+      multi_json (>= 1.3)
+      securecompare
+      url_safe_base64
+    keratin-authn (0.4.1)
+      json-jwt
+      lru_redux
+    lru_redux (1.1.0)
+    minitest (5.10.1)
+    multi_json (1.12.1)
     puma (3.7.0)
     rack (1.6.5)
     rack-protection (1.5.3)
       rack
+    securecompare (1.0.0)
     sequel (4.43.0)
     sinatra (1.4.8)
       rack (~> 1.5)
@@ -14,12 +35,17 @@ GEM
       sequel (>= 3.2.0)
       sinatra (>= 0.9.4)
     sqlite3 (1.3.13)
+    thread_safe (0.3.6)
     tilt (2.0.6)
+    tzinfo (1.2.3)
+      thread_safe (~> 0.1)
+    url_safe_base64 (0.2.2)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
+  keratin-authn
   puma
   sinatra
   sinatra-sequel

app.rb

@@ -9,6 +9,14 @@
   end
 end
 
+Keratin::AuthN.config.tap do |config|
+  # The base URL of your Keratin AuthN service
+  config.issuer = "https://keratin-authn-demo.herokuapp.com"
+
+  # The domain of your application
+  config.audience = 'localhost'
+end
+
 class User < Sequel::Model
 end
 

views/layout.erb

@@ -10,5 +10,13 @@
     </nav>
     <%= yield %>
   </div>
+
+  <script src="https://cdnjs.cloudflare.com/ajax/libs/es6-promise/4.0.5/es6-promise.auto.min.js"></script>
+  <script src="https://unpkg.com/keratin-authn@0.10.0/dist/keratin-authn.min.js"></script>
+  <script>
+    KeratinAuthN.setHost("<%= Keratin::AuthN.config.issuer %>");
+    KeratinAuthN.setCookieStore('authn');
+    KeratinAuthN.restoreSession().catch(console.log);
+  </script>
 </body>
 </html>