refactor(file retrieval): use ciphered query params instead of cookie to move email

app/controllers/recoveries_controller.rb

@@ -18,15 +18,17 @@ class RecoveriesController < ApplicationController
   end
 
   def post_identification
-    # cookies are used to avoid leaking
-    # email in url
-    cookies[:recover_previous_email] = previous_email
+    # cipher previous_user email
+    # to avoid leaks in the url
+    ciphered_email = cipher(previous_email)
 
-    redirect_to selection_recovery_path
+    redirect_to selection_recovery_path(ciphered_email:)
   end
 
   def selection
-    previous_user = User.find_by(email: cookies[:recover_previous_email])
+    @previous_email = uncipher(params[:ciphered_email])
+
+    previous_user = User.find_by(email: @previous_email)
 
     @recoverables = RecoveryService
       .recoverable_procedures(previous_user:, siret:)
@@ -35,7 +37,7 @@ class RecoveriesController < ApplicationController
   end
 
   def post_selection
-    previous_user = User.find_by(email: cookies[:recover_previous_email])
+    previous_user = User.find_by(email: previous_email)
 
     RecoveryService.recover_procedure!(previous_user:,
                           next_user: current_user,
@@ -58,6 +60,9 @@ class RecoveriesController < ApplicationController
   def previous_email = params[:previous_email]
   def procedure_ids = params[:procedure_ids].map(&:to_i)
 
+  def cipher(email) = message_verifier.generate(email, purpose: :agent_files_recovery, expires_in: 1.hour)
+  def uncipher(email) = message_verifier.verified(email, purpose: :agent_files_recovery) rescue nil
+
   def structure_name
     # we know that the structure exists because
     # of the ensure_collectivite_territoriale guard

app/views/recoveries/selection.html.haml

@@ -16,4 +16,5 @@
             = check_box_tag 'procedure_ids[]', procedure_id, false, class: 'fr-checkbox', id: procedure_id
             = label_tag procedure_id, libelle, class: 'fr-label'
 
+    = hidden_field_tag 'previous_email', @previous_email
     %button.fr-btn{ disabled: true,  data: { 'enable-submit-if-checked-target': 'submit' } } Continuer

spec/controllers/recoveries_controller_spec.rb

@@ -100,8 +100,9 @@ describe RecoveriesController, type: :controller do
       subject { post :post_identification, params: { previous_email: 'email@a.com' } }
 
       it do
-        is_expected.to redirect_to(selection_recovery_path)
-        expect(cookies[:recover_previous_email]).to eq('email@a.com')
+        response = subject
+        expect(response).to have_http_status(:redirect)
+        expect(response.location).to start_with(selection_recovery_url)
       end
     end