Generate BlackMatter checksum

blackmatter_checksum.py

import sys, struct, base64, argparse

def gen_id_from_guid(guid: str) -> str:
	checksum = checksum_string(guid + '\0')
	b64 = base64.b64encode(checksum.to_bytes(8, 'little'))[0:9]
	return b64.decode('utf-8').replace('+', 'x').replace('/', 'i').replace('=', 'z')

def gen_checksum_from_bytes(blob: str) -> str:
	blob = bytearray.fromhex(blob)
	return checksum(blob, len(blob))

def swap32(i):
    return struct.unpack("<I", struct.pack(">I", i))[0]
	
max_bits = 32
ROR4 = lambda val, r_bits: \
    ((val & (2**max_bits-1)) >> r_bits%max_bits) | \
    (val << (max_bits-(r_bits%max_bits)) & (2**max_bits-1))
	
def checksum_round(buffer, length, initial):
	result_upper, result_lower = initial >> 16, initial & 0xFFFF
	while length > 0:
		v8 = 0xFA1
		if (length < 0xFA1):
			v8 = length
		length -= v8
		i = 0
		while v8 > 0:
			result_lower += buffer[i]
			result_upper += result_lower
			v8 -= 1
			i += 1
		result_upper = result_upper % 0x1000F
		result_lower = result_lower % 0x1000F
	return (result_upper << 16) + result_lower

def checksum(buffer, length):
	v3 = checksum_round(buffer, length, 0xD6917A)
	v4 = checksum_round(buffer, length, swap32(v3))
	return swap32(checksum_round(buffer, length, swap32(v4)))

def checksum_string_round(string: str, length: int, initial: int) -> int:
	i = 0
	while i < length:
		c = ord(string[i])
		if c >= 0x41 and c <= 0x5A:
			c |= 0x20
		initial = (c + (ROR4(initial, 13)) & 0xFFFFFFFF)
		i += 1
	return initial

def checksum_string(string: str) -> int:
	v3 = checksum_string_round(string, len(string), 0xFFFFFFFF)
	v4 = checksum_string_round(string, len(string), v3)
	v11_0 = checksum_string_round(string, len(string), v4)
	v11_1 = swap32(v11_0)
	return (v11_1 << 32) | v11_0

if __name__ == '__main__':

	header = 'Generate BlackMatter ID or checksum'
	parser = argparse.ArgumentParser(description=header)
	group = parser.add_mutually_exclusive_group(required=True)
	group.add_argument('-g', '--guid', help='Machine GUID')
	group.add_argument('-b', '--blob', help='Blob bytes')
	
	args = parser.parse_args()
	
	if args.guid:
		id = gen_id_from_guid(args.guid)
		print('ID: ' + id)
		print('Extension: .' + id)
	elif args.blob:
		print('Checksum: ' + hex(gen_checksum_from_bytes(args.blob)))