How to create dynamic attr_accessors (getters/setters) for encrypted attributes in a Ruby on Rails 5 Model.

encryptor.rb

# lib/encryptor.rb
# Module to dynamic encrypt attributes per model
module Encryptor
  def has_encrypted_attributes(*attrs)
    attrs.each do |attr|
      # Define the dynamic getter
      define_method(attr) do
        self[attr].present? ? Encryptor.crypt.decrypt_and_verify(self[attr]) : self[attr]
      end
      # Define the dynamic setter
      define_method("#{attr.to_s}=") do |val|
        super(Encryptor.crypt.encrypt_and_sign(val))
      end
    end
  end

  protected

  # Create the base MessageEncryptor based on Rails secret_key_base
  def self.crypt
    ActiveSupport::MessageEncryptor.new(Rails.application.secrets.secret_key_base)
  end
end

model_with_encrypted_atts.rb

# app/models/model_with_encrypted_atts.rb
class ModelWithEncryptedAttrs < ApplicationRecord
  # Modules
  extend Encryptor

  # Abilities
  has_encrypted_attributes :attribute_1,
                           :attribute_2

end