diff --git a/app/models/comment.rb b/app/models/comment.rb
index da4f0a6f7..1fac00c8d 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -29,6 +29,8 @@ class Comment < ActiveRecord::Base
 
   has_many :reports, as: :item
 
+  has_one :signature, class_name: "CommentSignature", dependent: :delete
+
   scope :including_author, -> { includes(:author => :profile) }
   scope :for_a_stream,  -> { including_author.merge(order('created_at ASC')) }
 
diff --git a/app/models/comment_signature.rb b/app/models/comment_signature.rb
new file mode 100644
index 000000000..357bcb3b8
--- /dev/null
+++ b/app/models/comment_signature.rb
@@ -0,0 +1,7 @@
+class CommentSignature < ActiveRecord::Base
+  include Diaspora::Signature
+
+  self.primary_key = :comment_id
+  belongs_to :comment
+  validates :comment, presence: true
+end
diff --git a/app/models/like.rb b/app/models/like.rb
index c04fe7fc8..78eb9c3da 100644
--- a/app/models/like.rb
+++ b/app/models/like.rb
@@ -10,6 +10,8 @@ class Like < ActiveRecord::Base
 
   include Diaspora::Relayable
 
+  has_one :signature, class_name: "LikeSignature", dependent: :delete
+
   alias_attribute :parent, :target
 
   class Generator < Diaspora::Federated::Generator
diff --git a/app/models/like_signature.rb b/app/models/like_signature.rb
new file mode 100644
index 000000000..6978704a9
--- /dev/null
+++ b/app/models/like_signature.rb
@@ -0,0 +1,7 @@
+class LikeSignature < ActiveRecord::Base
+  include Diaspora::Signature
+
+  self.primary_key = :like_id
+  belongs_to :like
+  validates :like, presence: true
+end
diff --git a/app/models/poll_participation.rb b/app/models/poll_participation.rb
index 67494e11d..8dba27465 100644
--- a/app/models/poll_participation.rb
+++ b/app/models/poll_participation.rb
@@ -7,6 +7,8 @@ class PollParticipation < ActiveRecord::Base
   belongs_to :poll
   belongs_to :poll_answer, counter_cache: :vote_count
 
+  has_one :signature, class_name: "PollParticipationSignature", dependent: :delete
+
   alias_attribute :parent, :poll
 
   validates :poll_answer, presence: true
diff --git a/app/models/poll_participation_signature.rb b/app/models/poll_participation_signature.rb
new file mode 100644
index 000000000..90701f286
--- /dev/null
+++ b/app/models/poll_participation_signature.rb
@@ -0,0 +1,7 @@
+class PollParticipationSignature < ActiveRecord::Base
+  include Diaspora::Signature
+
+  self.primary_key = :poll_participation_id
+  belongs_to :poll_participation
+  validates :poll_participation, presence: true
+end
diff --git a/app/models/signature_order.rb b/app/models/signature_order.rb
new file mode 100644
index 000000000..83cbfb51a
--- /dev/null
+++ b/app/models/signature_order.rb
@@ -0,0 +1,3 @@
+class SignatureOrder < ActiveRecord::Base
+  validates :order, presence: true, uniqueness: true
+end
diff --git a/lib/diaspora/signature.rb b/lib/diaspora/signature.rb
new file mode 100644
index 000000000..e2b49caef
--- /dev/null
+++ b/lib/diaspora/signature.rb
@@ -0,0 +1,14 @@
+module Diaspora
+  module Signature
+    def self.included(model)
+      model.class_eval do
+        belongs_to :signature_order
+        validates :signature_order, presence: true
+
+        validates :author_signature, presence: true
+
+        serialize :additional_data, Hash
+      end
+    end
+  end
+end