diff --git a/Gemfile.lock b/Gemfile.lock
index c077593e..823f65e2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,6 +1,6 @@
 GIT
   remote: https://github.com/SaitoWu/grack.git
-  revision: dd990d231ac9189046b71a65d874638e55320e27
+  revision: ba46f3b0845c6a09d488ae6abdce6ede37e227e8
   specs:
     grack (1.0.0)
       rack (~> 1.4.1)
diff --git a/config/initializers/grack_auth.rb b/config/initializers/grack_auth.rb
index 17d3641a..27a0a1db 100644
--- a/config/initializers/grack_auth.rb
+++ b/config/initializers/grack_auth.rb
@@ -2,7 +2,30 @@ module Grack
   class Auth < Rack::Auth::Basic
 
     def valid?
-      true
-    end
-  end
-end
+      # Authentication with username and password
+      email, password = @auth.credentials
+      user = User.find_by_email(email)
+      return false unless user.valid_password?(password)
+
+      # Find project by PATH_INFO from env
+      if m = /^\/([\w-]+).git/.match(@env['PATH_INFO']).to_a
+        return false unless project = Project.find_by_path(m.last)
+      end
+
+      # Git upload and receive
+      if @env['REQUEST_METHOD'] == 'GET'
+        true
+      elsif @env['REQUEST_METHOD'] == 'POST'
+        if @env['REQUEST_URI'].end_with?('git-upload-pack')
+          return project.dev_access_for?(user)
+        elsif @env['REQUEST_URI'].end_with?('git-upload-pack')
+          #TODO master branch protection
+          return project.dev_access_for?(user)
+        else
+          false
+        end
+      end
+
+    end# valid?
+  end# Auth
+end# Grack