re_sign

# File lib/rubygems/security.rb, line 484
  def self.re_sign expired_certificate, private_key, age = ONE_YEAR,
                   extensions = EXTENSIONS
    raise Gem::Security::Exception,
          "incorrect signing key for re-signing " +
          "#{expired_certificate.subject}" unless
      expired_certificate.public_key.to_pem == private_key.public_key.to_pem

    unless expired_certificate.subject.to_s ==
           expired_certificate.issuer.to_s then
      subject = alt_name_or_x509_entry expired_certificate, :subject
      issuer  = alt_name_or_x509_entry expired_certificate, :issuer

      raise Gem::Security::Exception,
            "#{subject} is not self-signed, contact #{issuer} " +
            "to obtain a valid certificate"
    end

    serial = expired_certificate.serial + 1

    create_cert_self_signed(expired_certificate.subject, private_key, age,
                            extensions, serial)
  end