diff --git a/app/models/user.rb b/app/models/user.rb
index fb701ce..6fd25e9 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -14,4 +14,13 @@ class User < ActiveRecord::Base
     write_attribute :email, value
     write_attribute :email_lower, value.downcase
   end
+
+  def remember_token
+    [id, Digest::SHA512.hexdigest(password_digest)].join('$')
+  end
+
+  def self.find_by_remember_token(token)
+    user = find_by_id(token.split('$').first)
+    (user && user.remember_token == token) ? user : nil
+  end
 end
diff --git a/test/models/user_test.rb b/test/models/user_test.rb
index 04b8b74..3e72997 100644
--- a/test/models/user_test.rb
+++ b/test/models/user_test.rb
@@ -12,4 +12,11 @@ class UserTest < ActiveSupport::TestCase
   test "should save lower email" do
     assert_equal "lower@example.com", create(:user, email: 'LOWER@example.com').email_lower
   end
+
+  test "should have remember token" do
+    user = create(:user)
+    assert_not_nil user.remember_token
+    assert_equal user, User.find_by_remember_token(user.remember_token)
+    assert_equal nil, User.find_by_remember_token('invalidtoken')
+  end
 end