Rails 7 Active Record Encryption key on a record level

Question

Hello all I would like to use Rails 7 attribute encryption on a model and have a unique key for each record. The main objective is that I would like to delete a key and never be able to decipher the encrypted information (on that record) again if requested.

I tested the code below and was able to encrypt the data in the DB, retrieve, and search, but the removal of the key is still allowing the retrieval of the information. Any help appreciated.

class User < ActiveRecord::Base
  after_initialize :user_encryption_key
  after_save   :create_key_record
  attr_accessor :p_encryption_key


  def self.instance_encryption_key
    if self.respond_to?(:p_encryption_key)
      puts "This is the key - #{self&.p_encryption_key}"
      self&.p_encryption_key
    else
      nil
    end
  end

  encrypts :last_name,
           deterministic: true,
           key: self.instance_encryption_key


  def user_encryption_key
    if user_id
      self.p_encryption_key = get_user_encryption_key
    else
      # new record without an ID let the after save create the DB
      # entry
      self.p_encryption_key = create_encryption_key
    end
  end

  def profile_key_name
    %{/user_key/#{user_id}}
  end

  def get_user_encryption_key
    Rails.cache.
      fetch(user_key_name) {create_encryption_key}
  end

  def create_encryption_key
    ActiveRecord::Encryption::KeyGenerator.new.
      generate_random_hex_key(length: 16)
  end

  def create_key_record
    if new_record?
      if p_encryption_key.nil?
        p_encryption_key = create_encryption_key
      end
      Rails.cache.
        fetch(profile_key_name) {create_encryption_key}
    end
  end    
end