# File lib/rubygems/security.rb, line 727
  def self.add_trusted_cert(cert, opt = {})
    opt = OPT.merge(opt)

    # get destination path
    path = Gem::Security::Policy.trusted_cert_path(cert, opt)

    # verify trust directory (can't write to nowhere, you know)
    verify_trust_dir(opt[:trust_dir], opt[:perms][:trust_dir])

    # write cert to output file
    File.open(path, 'wb') do |file|
      file.chmod(opt[:perms][:trusted_cert])
      file.write(cert.to_pem)
    end

    # return nil
    nil
  end