diff --git a/app/services/bill_signature_service.rb b/app/services/bill_signature_service.rb
new file mode 100644
index 000000000..f8640a4b1
--- /dev/null
+++ b/app/services/bill_signature_service.rb
@@ -0,0 +1,16 @@
+class BillSignatureService
+  def self.grouped_unsigned_operation_until(date)
+    unsigned_operations = DossierOperationLog
+      .where(bill_signature: nil)
+      .where('executed_at < ?', date)
+
+    unsigned_operations.group_by { |e| e.executed_at.to_date }
+  end
+
+  def self.sign_operations(operations, day)
+    bill = BillSignature.build_with_operations(operations, day)
+    signature = Universign::API.timestamp(bill.digest)
+    bill.set_signature(signature, day)
+    bill.save!
+  end
+end
diff --git a/spec/services/bill_signature_service_spec.rb b/spec/services/bill_signature_service_spec.rb
new file mode 100644
index 000000000..2a88478df
--- /dev/null
+++ b/spec/services/bill_signature_service_spec.rb
@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+describe BillSignatureService do
+  describe ".grouped_unsigned_operation_until" do
+    subject { BillSignatureService.grouped_unsigned_operation_until(date).length }
+
+    let(:date) { Date.today }
+
+    context "when operations of several days need to be signed" do
+      before do
+        create :dossier_operation_log, executed_at: 3.days.ago
+        create :dossier_operation_log, executed_at: 2.days.ago
+        create :dossier_operation_log, executed_at: 1.day.ago
+      end
+
+      it { is_expected.to eq 3 }
+    end
+
+    context "when operations on a single day need to be signed" do
+      before do
+        create :dossier_operation_log, executed_at: 1.day.ago
+        create :dossier_operation_log, executed_at: 1.day.ago
+      end
+
+      it { is_expected.to eq 1 }
+    end
+
+    context "when there are no operations to be signed" do
+      before do
+        create :dossier_operation_log, created_at: 1.day.ago, bill_signature: build(:bill_signature)
+        create :dossier_operation_log, created_at: 1.day.from_now
+      end
+
+      it { is_expected.to eq 0 }
+    end
+  end
+end