Take a list of https://crt.sh/ IDs and produce binary forms of the Subject DNs

crtshToDNStruct.py

import sys, re, requests
from cryptography import x509
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.x509.oid import NameOID

def hex_string_for_struct(bytes):
  return [ "0x{:02X}".format(x) for x in bytes ]

def hex_string_human_readable(bytes):
  return [ "{:02X}".format(x) for x in bytes ]

def print_block(cert):
  country = cert.subject.get_attributes_for_oid(NameOID.COUNTRY_NAME)[0].value
  organization_name = cert.subject.get_attributes_for_oid(NameOID.ORGANIZATION_NAME)[0].value
  common_name = cert.subject.get_attributes_for_oid(NameOID.COMMON_NAME)[0].value

  block_name = "CA{}DN".format(re.sub(r'[-:=_. ]', '', common_name))

  octets = hex_string_for_struct(cert.subject.public_bytes(default_backend()))
  fingerprint = hex_string_human_readable(cert.fingerprint(hashes.SHA256()))

  print("// /C={C}/O={O}/CN={CN}"
        .format(C=country, O=organization_name, CN=common_name))
  print("// SHA256 Fingerprint: " + ":".join(fingerprint[:16]))
  print("//                     " + ":".join(fingerprint[16:]))
  print("// https://crt.sh/?id={crtsh} (crt.sh ID={crtsh})"
        .format(crtsh=crtshId))
  print("static const uint8_t {}[{}] = ".format(block_name, len(octets)) + "{")

  while len(octets) > 0:
    print("  " + ", ".join(octets[:13]) + ",")
    octets = octets[13:]

  print("};")
  print()

  return block_name

if __name__ == "__main__":
  blocks = []

  certshIds = sys.argv[1:]
  print("// Script downloaded from https://gist.github.com/ed5d869cd8da3951e393f4a2d8a3391f")
  print("// Invocation: {} {}".format(sys.argv[0], " ".join(certshIds)))
  print()
  for crtshId in certshIds:
    r = requests.get('https://crt.sh/?d={}'.format(crtshId))
    r.raise_for_status()

    cert = x509.load_pem_x509_certificate(r.content, default_backend())
    blocks.append(print_block(cert))

  print("static const DataAndLength RootDNs[]= {")
  for structName in blocks:
    print("  { " + "{},".format(structName))
    print("    sizeof({})".format(structName) + " }")
  print("};")