Random generate access code

access_code_generator.rb

class AccessCodeGenerator
  def self.generate(size = 13)
    charset = ([*('A'..'Z'),*('0'..'9')]-%w(0 1 5 8 B I L O S U))
    (0...size).map{ charset.to_a[SecureRandom.random_number(charset.size)] }.join
  end
end