class Gem::Security::Signer

def extract_name cert # :nodoc:
  subject_alt_name = cert.extensions.find { |e| 'subjectAltName' == e.oid }
  if subject_alt_name then
    /\Aemail:/ =~ subject_alt_name.value
    $' || subject_alt_name.value
  else
    cert.subject
  end
end

def initialize key, cert_chain, passphrase = nil
  @cert_chain = cert_chain
  @key        = key
  unless @key then
    default_key  = File.join Gem.default_key_path
    @key = default_key if File.exist? default_key
  end
  unless @cert_chain then
    default_cert = File.join Gem.default_cert_path
    @cert_chain = [default_cert] if File.exist? default_cert
  end
  @digest_algorithm = Gem::Security::DIGEST_ALGORITHM
  @digest_name      = Gem::Security::DIGEST_NAME
  @key = OpenSSL::PKey::RSA.new File.read(@key), passphrase if
    @key and not OpenSSL::PKey::RSA === @key
  if @cert_chain then
    @cert_chain = @cert_chain.compact.map do |cert|
      next cert if OpenSSL::X509::Certificate === cert
      cert = File.read cert if File.exist? cert
      OpenSSL::X509::Certificate.new cert
    end
    load_cert_chain
  end
end

def load_cert_chain # :nodoc:
  return if @cert_chain.empty?
  while @cert_chain.first.issuer.to_s != @cert_chain.first.subject.to_s do
    issuer = Gem::Security.trust_dir.issuer_of @cert_chain.first
    break unless issuer # cert chain is verified later
    @cert_chain.unshift issuer
  end
end

def re_sign_key # :nodoc:
  old_cert = @cert_chain.last
  disk_cert_path = File.join Gem.default_cert_path
  disk_cert = File.read disk_cert_path rescue nil
  disk_key  =
    File.read File.join(Gem.default_key_path) rescue nil
  if disk_key == @key.to_pem and disk_cert == old_cert.to_pem then
    expiry = old_cert.not_after.strftime '%Y%m%d%H%M%S'
    old_cert_file = "gem-public_cert.pem.expired.#{expiry}"
    old_cert_path = File.join Gem.user_home, ".gem", old_cert_file
    unless File.exist? old_cert_path then
      Gem::Security.write old_cert, old_cert_path
      cert = Gem::Security.re_sign old_cert, @key
      Gem::Security.write cert, disk_cert_path
      @cert_chain = [cert]
    end
  end
end

def sign data
  return unless @key
  if @cert_chain.length == 1 and @cert_chain.last.not_after < Time.now then
    re_sign_key
  end
  full_name = extract_name @cert_chain.last
  Gem::Security::SigningPolicy.verify @cert_chain, @key, {}, {}, full_name
  @key.sign @digest_algorithm.new, data
end