Rename PEM certificates to CN and date

rename_pem_certs

#!/usr/bin/ruby

require 'openssl'
require 'date'

Dir.chdir('/Users/thomas/Desktop/certs')

Dir.glob('./*.pem') do |file|
  next if file =~ /.k.pem$/
  puts file
  raw = File.read file
  cert = OpenSSL::X509::Certificate.new(raw)
  valid_until = cert.not_after.to_date.xmlschema
  subject = OpenSSL::X509::Name.new(cert.subject).to_a
  subject_hash = Hash[*subject.transpose[0..-2].transpose.flatten]
  cn = subject_hash['CN'].gsub(/\*/,'STAR')
  filename = "#{cn}_until_#{valid_until}"
  puts "#{file} => #{filename}.pem"
  File.rename(file, "#{filename}.pem")
end