new_contents: #!/usr/bin/env python
  
  import os
  import sys
  import base64 as b64
  import argparse
  
  def smimea(usage, der):
      cert = []
  
      c = 0
      with open(der, "rb") as f:
          while True:
              l = f.read(1024)
              if l == "": break
  
              c += len(l)
              cert.append(l)
  
      data = b64.b16encode("".join(cert))
      print "\# %i 0%i000000%s" % (c + 4, usage, data)
  
  if __name__ == "__main__":
      parser = argparse.ArgumentParser(epilog="Generate SMIMEA RDATA for DNS")
      parser.add_argument("--usage-field",
                          "-u",
                          default=1,
                          type=int,
                          choices=(1, 3),
                          help="Certificate usage field")
      parser.add_argument("--email",
                          "-e",
                          default="",
                          type=str,
                          help="Create SHA224 LHS for an email address")
      parser.add_argument("--cert",
                          "-c",
                          default="",
                          required=True,
                          help="x509 certificate in DER format")
      
      args = parser.parse_args()
  
      if not os.path.exists(args.cert):
          print("File not found: '%s'" % args.cert)
          sys.exit(os.EX_USAGE)
  
      if args.email is not "":
          import hashlib
          local, domain = args.email.split("@")
          print hashlib.sha224(local).hexdigest() + \
                              "._encr._smimecert.%s. IN TYPE65514" % domain,
  
      smimea(args.usage_field, args.cert)
      sys.exit(os.EX_OK)
  
subject: Add little helper script to create DNS records