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import os, sys
from itertools import product
from multiprocessing import Pool, cpu_count
from binascii import unhexlify
import tqdm
def load_samples(folder):
msgs, crcs = [], []
for fn in os.listdir(folder):
with open(os.path.join(folder,fn),'r') as f:
for L in f:
if '=' not in L: continue
h,c = L.strip().split('=',1)
try:
msgs.append(unhexlify(h))
crcs.append(int(c,16))
except:
pass
return msgs, crcs
def calc_crc8(data, poly, init, xorout, ri, ro):
crc = init
for b in data:
if ri: b = int('{:08b}'.format(b)[::-1],2)
crc ^= b
for _ in range(8):
crc = ((crc << 1) ^ poly) & 0xFF if crc & 0x80 else (crc << 1) & 0xFF
if ro: crc = int('{:08b}'.format(crc)[::-1],2)
return crc ^ xorout
def test_config(args):
poly, init, xorout, ri, ro, msgs, crcs = args
ok = 0
total = len(msgs)
for d, chk in zip(msgs, crcs):
if calc_crc8(d, poly, init, xorout, ri, ro) == chk:
ok += 1
return (poly, init, xorout, ri, ro, ok, total)
def main(folder):
msgs, crcs = load_samples(folder)
if len(msgs) < 2:
sys.exit("Need at least 2 samples")
tasks = [
(poly, init, xorout, ri, ro, msgs, crcs)
for poly in range(256) if (poly & 1 or poly == 1)
for init, xorout, ri, ro in product(range(256), range(256), [False, True], [False, True])
]
print(f"Wasting ressources on {len(tasks):,} configs using {cpu_count()} cores... yea")
best = []
target = len(msgs)
with Pool() as p:
for poly, init, xorout, ri, ro, ok, total in tqdm.tqdm(p.imap_unordered(test_config, tasks), total=len(tasks)):
if ok == total:
print("FOUND FULL FUCKING MATCH ✅", f"poly=0x{poly:02X}", f"init=0x{init:02X}",
f"xorout=0x{xorout:02X}", f"ri={ri}", f"ro={ro}")
return
# keep top-5 partials
best.append((ok, poly, init, xorout, ri, ro))
best = sorted(best, reverse=True)[:5]
print("\n=== TOP PARTIAL MATCHES ===")
for ok, poly, init, xorout, ri, ro in best:
print(f"{ok}/{total} matches – poly=0x{poly:02X}, init=0x{init:02X}, xorout=0x{xorout:02X}, ri={ri}, ro={ro}")
print("👎 No full match found.")
if __name__ == '__main__':
if len(sys.argv) != 2:
sys.exit(f"Usage: python {sys.argv[0]} <samples_folder>")
main(sys.argv[1])
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