Simple encryption and decryption function for Ruby on Rails 5.

encrypt_decrypt_in_rails.rb

# Assuming your Secret Key Base is in Rails.application.secrets.secret_key_base

def encrypt text
  text = text.to_s unless text.is_a? String

  len   = ActiveSupport::MessageEncryptor.key_len
  salt  = SecureRandom.hex len
  key   = ActiveSupport::KeyGenerator.new(Rails.application.secrets.secret_key_base).generate_key salt, len
  crypt = ActiveSupport::MessageEncryptor.new key
  encrypted_data = crypt.encrypt_and_sign text
  "#{salt}$$#{encrypted_data}"
end

def decrypt text
  salt, data = text.split "$$"
  
  len   = ActiveSupport::MessageEncryptor.key_len
  key   = ActiveSupport::KeyGenerator.new(Rails.application.secrets.secret_key_base).generate_key salt, len
  crypt = ActiveSupport::MessageEncryptor.new key
  crypt.decrypt_and_verify data
end