gistfile1.txt

#!/usr/bin/ruby

require 'openssl'

cert = OpenSSL::X509::Certificate.new File.read(ARGV[0])
cn = cert.subject.to_a.select{|oid, value| oid == "CN"}[0][1]

puts "Cert metadata"
puts cert.serial
puts cert.issuer
puts cert.not_before
puts cert.not_after
puts cert.signature_algorithm
puts cert.to_s
puts "Public key metadata"
puts cert.public_key.class
puts cert.public_key.to_s


sans = []
cert.extensions.each do |ext|
  next if ext.oid != "subjectAltName"
  ostr = OpenSSL::ASN1.decode(ext.to_der).value.last
  sequence = OpenSSL::ASN1.decode(ostr.value)
  sequence.value.each do |san|
    sans << san.value
  end
end

puts "CN: #{cn}"
puts "SANS: #{sans.join(', ')}"