Use interactor validation

app/controllers/asymmetric_keys_controller.rb

@@ -32,10 +32,13 @@ class AsymmetricKeysController < ApplicationController
     @asymmetric_key_form = AsymmetricKeyForm.new asymmetric_key_form_params
     authorize @asymmetric_key_form
 
-    return render :new unless @asymmetric_key_form.valid?
-
     result = ImportAsymmetricKey.call @asymmetric_key_form.attributes
 
+    if result.failure?
+      @asymmetric_key_form.errors.add :public_key_pem
+      return render :new
+    end
+
     redirect_to after_create_url result.asymmetric_key
   end
 

app/forms/asymmetric_key_form.rb

@@ -1,14 +1,8 @@
 # frozen_string_literal: true
 
 class AsymmetricKeyForm < ApplicationForm
-  attr_reader :public_key_openssl_pkey
-
   attribute :public_key_pem, :string
 
-  before_validation :set_public_key_openssl_pkey
-
-  validates :public_key_pem, presence: true
-
   def self.model_name
     ActiveModel::Name.new(self, nil, AsymmetricKey.name)
   end
@@ -16,15 +10,4 @@ class AsymmetricKeyForm < ApplicationForm
   def self.policy_class
     'AsymmetricKeyPolicy'
   end
-
-private
-
-  def set_public_key_openssl_pkey
-    return @public_key_openssl_pkey = nil if public_key_pem.blank?
-
-    @public_key_openssl_pkey = OpenSSL::PKey.read public_key_pem
-  rescue OpenSSL::OpenSSLError
-    @public_key_openssl_pkey = nil
-    errors.add :public_key_pem
-  end
 end