Gem::Security.re_sign

# File tmp/rubies/ruby-3.0.5/lib/rubygems/security.rb, line 524
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 == get_public_key(private_key).to_pem

  unless expired_certificate.subject.to_s ==
         expired_certificate.issuer.to_s
    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