class PDF::Reader::SecurityHandlerFactory

def self.build(encrypt, doc_id, password)
  doc_id   ||= []
  password ||= ""
  if encrypt.nil?
    NullSecurityHandler.new
  elsif standard?(encrypt)
    build_standard_handler(encrypt, doc_id, password)
  elsif standard_v5?(encrypt)
    build_v5_handler(encrypt, doc_id, password)
  else
    UnimplementedSecurityHandler.new
  end
end