cert2header_multi.py

# Author Vysakh P Pillai
#
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# SOFTWARE.

from string import Template
import binascii
from cryptography import x509
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.backends import default_backend
import sys
import re

def make_sublist_group(lst: list, grp: int) -> list:
    """
    Group list elements into sublists.
    make_sublist_group([1, 2, 3, 4, 5, 6, 7], 3) = [[1, 2, 3], [4, 5, 6], 7]
    """
    return [lst[i:i+grp] for i in range(0, len(lst), grp)]

def do_convension(content: bytes) -> str:
    hexstr = binascii.hexlify(content).decode("UTF-8")
    hexstr = hexstr.upper()
    array = ["0x" + hexstr[i:i + 2] + "" for i in range(0, len(hexstr), 2)]
    array = make_sublist_group(array, 10)
    
    return sum(len(a) for a in array ), "\n".join([", ".join(e) + ", " for e in array])


# find number of arguments
argCount = len(sys.argv)

#check if all the arguments correspond to valid PEM certificates. if not error out. if yes, parse them into a list
certList={}
for i in range(1,argCount):
    with open(sys.argv[i], "rb") as certfile:
        certData=certfile.read()
        cert = x509.load_pem_x509_certificate(certData, default_backend())
        keySize=cert.public_key().key_size
        certSubject=re.sub('[^0-9a-zA-Z]+', '_', cert.subject.rfc4514_string()).strip("CN").strip("_")
        certList[certSubject]=[keySize]
        certList[certSubject]=certList[certSubject]+list(do_convension(certData))


certHeaderTemplate=Template("""/*GENERATED FILE*/

#ifndef _CERTS_TEST_H_
#define _CERTS_TEST_H_

$CERTS
#endif /*_CERTS_TEST_H_*/
""")

certs=""
for key, value in certList.items():
    certArrayString=f"""static const unsigned char {key}_der[] =
{{
/*key size is {value[0]}*/
{value[2]}
}};
/* size is {value[1]} */
static const int sizeof_{key}_der = sizeof({key}_der);

"""
    certs=certs+certArrayString

with open('cert_header.h', 'w') as file: 
    file.write(certHeaderTemplate.substitute(CERTS=certs))