module Gem::Security

def self.sign certificate, signing_key, signing_cert,
              age = ONE_YEAR, extensions = EXTENSIONS, serial = 1
  signee_subject = certificate.subject
  signee_key     = certificate.public_key
  alt_name = certificate.extensions.find do |extension|
    extension.oid == 'subjectAltName'
  end
  extensions = extensions.merge 'subjectAltName' => alt_name.value if
    alt_name
  issuer_alt_name = signing_cert.extensions.find do |extension|
    extension.oid == 'subjectAltName'
  end
  extensions = extensions.merge 'issuerAltName' => issuer_alt_name.value if
    issuer_alt_name
  signed = create_cert signee_subject, signee_key, age, extensions, serial
  signed.issuer = signing_cert.subject
  signed.sign signing_key, Gem::Security::DIGEST_ALGORITHM.new
end