How to Migrate to Rails Encrypted Attributes

This post will show you how to migrate an existing attribute to a Rails 7 encrypted attribute.

Rails 7 has shipped with encrypted attributes, so its no longer necessary to use something like attr_encrypted to encrypt a field.

Once set up, using it is easy:

class Person < ApplicationRecord
  encrypts :ssn
end

This works great if you have never happened to have any unencrypted values in your model. But what if you have an existing attribute that’s not encrypted and want to make it encrypted? Here’s how to do it …

How to migrate an existing attribute to an encrypted attribute

Let’s assume you forgot to encrypt your :ssn attribute on the Person class:

class Person < ApplicationRecord
  # has a first_name, last_name, ssn, etc
  # none are encrypted
end

Let’s assume you forgot to encrypt your :ssn attribute on the Person class:

1. Run the installer: rails db:encryption:init
   • This will add active_record_encryption values to your target environment credentials. Be sure to add it to your other environments too. (more info)
2. Set config.active_record.encryption.support_unencrypted_data = true in your environment files. e.g. – production.rb and developement.rb
3. Encrypt the field:

class Person < ApplicationRecord
    encrypts :ssn
end

4. Generate a migration to encrypt the existing values:

class EncryptPersonDetails < ActiveRecord::Migration[7.0]
  def up
    people =  Person.all
    people.each do |person|
      person.encrypt
    end
  end

  def down
   # Needed in the config you're using (production.rb, development.rb)
   # config.active_record.encryption.support_unencrypted_data = true
   people =  Person.all
   people.each do |person|
      person.decrypt
    end
  end
end

5. Commit and deploy

6. Once migrated, create another commit that removes the following: config.active_record.encryption.support_unencrypted_data = true from your environment files and deploy that.

That’s it; now your Person model has an encrypted field. Enjoy.

More info: Active Record Encryption docs